public function actionView(int $id, string $slug = null): string
{
if (!is_null($slug)) {
$model = $this->findModelSlug($slug);

    }
    else {
        $model = $this->findModel($id);
    }
    
    /**
    * Product Category Slug is 'page layout'.
    * Calling getCategory() $category of the product And fetch the getParent() 
    * $parent category's slug.
    */
    $category = $model->category;
    $parentSlug = (!empty($category->parent->slug)) ? $category->parent->slug : false;
    switch ($parentSlug) {
        case 'news' :
            $renderView = 'news';
            break;
        case 'gallery' :
            $renderView = 'gallery';
            break;
        case 'artists' :
            $renderView = 'artists';
            break;
        default :
            $renderView = 'view';
            break;
    }

i need a yii2 controller name that best suits the idea of a art gallery.. not "post"

For a Yii2 controller that represents the idea of an art gallery and handles items such as artworks, exhibitions, artists, or gallery-related content, here are some suitable controller name suggestions that go beyond the generic "PostController":

    GalleryController — A classic choice, for managing galleries or a collection of artworks.
    ArtworkController — If you’re managing individual art pieces.
    ExhibitionController — If the focus is on exhibitions or events.
    ArtistController — If the focus is on artists and their profiles.
    CollectionController — If you want to emphasize curated collections of art.
    ArtPieceController — Another clear option for individual artworks.

Given your existing code snippet references categories such as 'news', 'gallery', and 'artists', it seems GalleryController fits well as the general controller name. It’s intuitive, directly representing an art gallery context and is broad enough to accommodate related entities.
Example

class GalleryController extends Controller
{
    public function actionView(int $id, string $slug = null): string
    {
        // ... your existing code here ...
    }
}

If your project is focused more on artworks or exhibits within the gallery, you might also adapt it accordingly. But generally, GalleryController is a great choice.

so you suggest breaking things up into each section instead of using slug as a way to have templates and use "articleController" or something like it

Great question! It depends on your app's complexity and how distinct those sections really are.
1. Single Controller with Slug-Based View Templates (Monolithic)

Pros:

    Simple entry point for similar content types.
    Easier to share common logic: loading model, authorization, rendering.
    Easy to add new "sections" just by adding new category slugs and view templates.

Cons:

    Overloaded controller with conditional logic (switch-case).
    Harder to maintain or add complex features per section.
    Mixing different domain concepts in one place.

2. Separate Controllers Per Section (GalleryController, NewsController, ArtistController...)

Pros:

    Clear separation of concerns.
    Each controller can have custom actions and workflow.
    Easier to apply section-specific business rules and validation.
    Cleaner, more maintainable codebase with distinct responsibilities.

Cons:

    Some shared logic may need duplication or refactoring into base classes or components.
    More files/controllers to navigate if the app is small/simple.

Recommendation for an Art Gallery App

If these categories are conceptually different and have unique workflows — for example:

    News articles or announcements (NewsController)
    Artworks displayed in galleries (GalleryController or ArtworkController)
    Artists' profiles and bios (ArtistController)

— then separate controllers are better.

Use slugs for SEO-friendly URLs and lookups, but keep rendering logic and workflows separated by controller.
Hybrid Approach

    Main entry could be a general ContentController or SiteController that routes requests to section controllers internally.
    You can also use modules for each section (modules/news, modules/gallery, modules/artists) for further separation.

Summary
Approach 	When to use 	Example Controller(s)
Single controller + slug 	Small app, very similar content types 	ArticleController or ContentController
Separate controllers 	Different domain logic per section 	GalleryController, NewsController, ArtistController

If you ask me:

For a professional art gallery site with multiple content types, create separate controllers reflecting those content types, and use slugs for friendly URLs inside each controller.

That will keep your code cleaner, easier to maintain, and more scalable over time.

so what are my other options than article, content, whatelse?

Great question! If you want alternatives to generic controller names like ArticleController or ContentController, here are some meaningful options tailored for an art gallery or creative content site:
1. GalleryController

    Manages collections of artworks, exhibitions, or spaces.
    Focused on presenting and managing art galleries and displays.

2. ArtworkController (or ArtController)

    Manages individual art pieces.
    Useful when you have detailed metadata per piece (artist, year, medium).

3. ExhibitionController

    For special events or exhibition shows.
    If your site frequently features temporary collections or shows.

4. ArtistController

    Manages profiles and portfolios of artists.
    Useful if artist information is a key part of your site.

5. NewsController

    Manages news, press releases, blog posts about the gallery or art world.

6. PortfolioController

    Manages collections of artworks or artist portfolios.
    Similar to Gallery/Artwork but a bit broader for personal portfolios.

7. StoryController or FeatureController

    To handle editorial content, stories, or features beyond simple articles.
    Useful if you want to convey a more narrative or curated experience.

8. ShowcaseController

    Emphasizes curated, selected works or exhibitions.
    Stylish naming for highlighted content.

9. CollectionController

    For groups of artworks logically grouped (by style, period, artist).

More Generic Yet Domain-Themed

    ItemController (generic “things” — art items, posts, etc.)
    MediaController (if content includes videos, images, interactive media)
    CatalogController (like a museum catalog of items)

Summary Table
Controller Name 	Best Use Case
GalleryController 	Managing galleries or collections of art
ArtworkController 	Managing individual artwork items
ExhibitionController 	Managing shows, expos, and events
ArtistController 	Managing artist info and portfolios
NewsController 	Handling news, press, and announcements
PortfolioController 	Artist portfolios or grouped collections
StoryController 	Editorial, narrative content beyond articles
ShowcaseController 	Highlighted or curated gallery content
CollectionController 	Groupings of artwork sets or themes
Final tip:

Choose the controller name based on how your site organizes content and the user experience you want to provide — it’s better to reflect your domain concepts clearly rather than default to generic terms.

If you want, I can help you draft a few sample controller skeletons based on one or more of these options! Would that be helpful?

i already have a purchaseController with a actionItem

Thanks for the extra context! Since you already have a PurchaseController and actionItem handling purchase-related stuff, that helps narrow down your naming choices for content controllers related to the gallery/artwork side.
Given that:

You ideally want a controller name that...

    Clearly separates content/viewing from purchase/transaction logic
    Reflects the gallery/art context
    Works well alongside your existing PurchaseController

Here are some suggestions that fit well:
Controller Name 	Why it fits 	Example Use
GalleryController 	Central place for viewing galleries/artworks and associated content 	Actions: actionView(), actionIndex() to show gallery contents
ArtworkController 	Focuses on individual art pieces, details 	Actions: actionView(), actionByArtist(), etc.
ExhibitionController 	For temporary or ongoing exhibitions/events 	Actions: actionView(), actionUpcoming(), etc.
ArtistController 	Profiles and bios of artists 	Actions: actionView(), actionList()
CatalogController 	Museum-style catalog of artworks 	Actions: actionView(), actionSearch()
CollectionController 	Grouped sets of artworks 	Actions: actionView(), actionByTheme()
Example:

Your URL schemes could look like this:

/gallery/view/123  => shows a gallery item or exhibit
/artwork/view/456  => shows details of an individual artwork
/artist/view/12    => artist profile page
/purchase/item/789 => buying or payment workflow

This keeps purchase and content clearly separated.
Why not ArticleController or ContentController?

    These are generic, more blog or news-like naming.
    Less clear when you have domain-specific logic for art, galleries, and artists.
    PurchaseController already contains transactional concerns, so keep content controllers dedicated to display and browsing.

Quick recommendation:

    Use GalleryController or ArtworkController for your main art content.
    Keep all purchase/payment related logic in PurchaseController.
    If your app grows, consider separate controllers per domain concept (Artist, Exhibition, News).

If you want, I can help you write stubs for GalleryController or ArtworkController to get you started! Just let me know.

so perhaps I am best off creating ExhibitionController(current art) and ArtistController(artists bios), ArticleController(handles news and such) and CatalogController

Yes, exactly — that sounds like a well-structured, clear approach!

By splitting your app like this, you separate concerns cleanly, which:

    Makes your codebase easier to maintain and extend.
    Helps future developers (or you!) quickly understand which controller does what.
    Allows you to tailor validation, presentation, and business logic to each content type.
    Keeps URLs semantic and SEO friendly.

Your proposed controllers:
Controller Name 	Purpose / Content
ExhibitionController 	Handling current and upcoming exhibits, with relevant info and artwork lists.
ArtistController 	Managing artists’ bios, profiles, portfolios, related info.
ArticleController 	News, press releases, blog posts, gallery updates, announcements.
CatalogController 	A museum-style catalog of artworks — searchable, browsable collections across categories.
Additional tips

    For shared functionality (e.g., loading a model by slug or ID), consider creating a base controller or trait to reuse code.
    Url rules can differentiate sections clearly, e.g.:

// config/web.php URL rules example
[
    'pattern' => 'exhibition/<slug>',
    'route' => 'exhibition/view',
],
[
    'pattern' => 'artist/<slug>',
    'route' => 'artist/view',
],
[
    'pattern' => 'news/<slug>',
    'route' => 'article/view',
],
[
    'pattern' => 'catalog/<id>',
    'route' => 'catalog/view',
],

    This keeps routes clean and semantic, improving both UX and SEO.

Final thoughts

This approach is common in professional, content-rich websites and aligns well with Yii2’s MVC principles. It soundly separates display content from transactional stuff like your PurchaseController.

If you want, I can help sketch out sample controllers or routing rules! Just say the word.

create these yii2 controllers

Certainly! Below are basic Yii2 controller skeletons for your proposed controllers:

    ExhibitionController
    ArtistController
    ArticleController (for news and blog posts)
    CatalogController

Each includes a simple actionView that can load a model by id or slug (adjust model classes and find methods as needed).
1. ExhibitionController.php

<?php

namespace app\controllers;

use Yii;
use yii\web\Controller;
use yii\web\NotFoundHttpException;
use app\models\Exhibition;

class ExhibitionController extends Controller
{
    /**
     * Display a single exhibition by ID or slug.
     * 
     * @param int|null $id
     * @param string|null $slug
     * @return string
     * @throws NotFoundHttpException
     */
    public function actionView(int $id = null, string $slug = null): string
    {
        $model = null;

        if ($slug !== null) {
            $model = Exhibition::find()->where(['slug' => $slug])->one();
        } elseif ($id !== null) {
            $model = Exhibition::findOne($id);
        }

        if ($model === null) {
            throw new NotFoundHttpException('The requested exhibition does not exist.');
        }

        return $this->render('view', ['model' => $model]);
    }

    // Add more actions as required, e.g., actionIndex() for listing exhibitions
}

2. ArtistController.php

<?php

namespace app\controllers;

use Yii;
use yii\web\Controller;
use yii\web\NotFoundHttpException;
use app\models\Artist;

class ArtistController extends Controller
{
    /**
     * Display a single artist profile by ID or slug.
     * 
     * @param int|null $id
     * @param string|null $slug
     * @return string
     * @throws NotFoundHttpException
     */
    public function actionView(int $id = null, string $slug = null): string
    {
        $model = null;

        if ($slug !== null) {
            $model = Artist::find()->where(['slug' => $slug])->one();
        } elseif ($id !== null) {
            $model = Artist::findOne($id);
        }

        if ($model === null) {
            throw new NotFoundHttpException('The requested artist does not exist.');
        }

        return $this->render('view', ['model' => $model]);
    }

    // Additional actions like actionIndex(), etc.
}

3. ArticleController.php

<?php

namespace app\controllers;

use Yii;
use yii\web\Controller;
use yii\web\NotFoundHttpException;
use app\models\Article;

class ArticleController extends Controller
{
    /**
     * Display a single article (news, blog post) by ID or slug.
     * 
     * @param int|null $id
     * @param string|null $slug
     * @return string
     * @throws NotFoundHttpException
     */
    public function actionView(int $id = null, string $slug = null): string
    {
        $model = null;

        if ($slug !== null) {
            $model = Article::find()->where(['slug' => $slug])->one();
        } elseif ($id !== null) {
            $model = Article::findOne($id);
        }

        if ($model === null) {
            throw new NotFoundHttpException('The requested article does not exist.');
        }

        return $this->render('view', ['model' => $model]);
    }

    // Additional actions such as actionIndex() for listing all news or articles
}

4. CatalogController.php

<?php

namespace app\controllers;

use Yii;
use yii\web\Controller;
use yii\web\NotFoundHttpException;
use app\models\Catalog;

class CatalogController extends Controller
{
    /**
     * View a catalog item by ID or slug.
     * 
     * @param int|null $id
     * @param string|null $slug
     * @return string
     * @throws NotFoundHttpException
     */
    public function actionView(int $id = null, string $slug = null): string
    {
        $model = null;

        if ($slug !== null) {
            $model = Catalog::find()->where(['slug' => $slug])->one();
        } elseif ($id !== null) {
            $model = Catalog::findOne($id);
        }

        if ($model === null) {
            throw new NotFoundHttpException('The requested catalog item does not exist.');
        }

        return $this->render('view', ['model' => $model]);
    }

    // Optionally add more actions like actionSearch(), actionIndex(), etc.
}

Notes

    Replace model classes (Exhibition, Artist, Article, Catalog) with your actual AR models.
    Implement find() or findOne() logic or methods according to your database schema.
    Your view files should go to the corresponding view folder, e.g., views/exhibition/view.php, etc.
    You might want to add behaviors such as access control, caching, or others as needed.
    Consider adding actionIndex() to list items, or other CRUD actions if applicable.

If you'd like, I can also help you with example URL rules or sample views for these controllers!

so these could be all controlled using the same post model, similar to the slug idea in breaking them up

Yes, technically you can use a single "Post" (or generic) model to handle all these content types — using attributes like type, category, or status to differentiate between Exhibitions, Artists, Articles, Catalog items, etc. — and have multiple controllers (or even a single controller) filter/query this model accordingly.
This is a very common pattern in CMS-like systems:

    A single table (say post) with columns:
        id
        slug
        title
        content
        type (e.g., 'exhibition', 'artist', 'article', 'catalog')
        category_id
        status
        created_at, etc.

Pros of Using a Single Post Model

    Simplifies database schema (one table).
    Easier to add new content types without schema changes.
    Common behavior/fields standardized in one model.
    Enables unified search, tagging, or categorization.

Cons

    Model may get complicated with many if ($this->type == 'artist') style conditionals in code or views.
    Validation rules can grow complex, needing different rules per type.
    Slower for some queries if different types have vastly different fields.
    Less clarity in code where things get mixed up, reducing maintainability.
    Harder to add type-specific relations or business logic without lots of conditional branching.

Balancing Approach

You can use single Post model + multiple controllers to separate logic and presentation. Each controller just scopes queries to that type, e.g.:

// In ExhibitionController.php
$exhibition = Post::find()->where(['type' => 'exhibition', 'slug' => $slug])->one();

Similarly for ArtistController.php, etc.

Or vice versa, a single controller (like ContentController) can route/render different views based on the type, similar to your original slug-switch idea.
Example: Single Post model with scoping in controllers

// ExhibitionController actionView
public function actionView(string $slug): string
{
    $model = Post::find()->where(['type' => 'exhibition', 'slug' => $slug])->one();
    if (!$model) {
       throw new NotFoundHttpException('Exhibition not found.');
    }
    return $this->render('view', ['model' => $model]);
}

Summary
Approach 	When is it best
Single Post Model + Multiple Controllers 	When content types share most fields and logic, but you want clear UX routes and distinct controllers
Single Post Model + Single Controller 	When content types are very similar, with minimal domain-specific behavior
Separate Models + Separate Controllers 	When content types vary greatly in structure and behavior
Final thoughts

If your Exhibition, Artist, Article, Catalog items have mostly common fields (title, body, slug) and minor behavioral differences, a single Post model + multiple controllers is a clean, flexible approach. But if these differ significantly, separate models might be better.

If you want, I can help sketch a single Post model structure with examples of filtering in controllers too!

using type should be more than fine for post model

Absolutely, using a type field in your Post model is a very practical and common approach, especially in a content-heavy application like an art gallery website.
Benefits recap:

    Single table that holds all content types (exhibitions, artists, articles, catalog items).
    Easy to filter by type in your queries.
    Common fields (title, slug, content, created_at) live in one place.
    Keep controllers focused on business logic and views for each type.
    Avoids duplication of almost identical models.

Quick Yii2 example of the Post AR model with type and simple scope methods

<?php

namespace app\models;

use yii\db\ActiveRecord;

class Post extends ActiveRecord
{
    const TYPE_EXHIBITION = 'exhibition';
    const TYPE_ARTIST = 'artist';
    const TYPE_ARTICLE = 'article';
    const TYPE_CATALOG = 'catalog';

    public static function tableName()
    {
        return 'post'; // your table name
    }

    /**
     * Scope method example for Exhibitions
     */
    public static function findExhibitions()
    {
        return self::find()->where(['type' => self::TYPE_EXHIBITION]);
    }

    /**
     * Scope method example for Artists
     */
    public static function findArtists()
    {
        return self::find()->where(['type' => self::TYPE_ARTIST]);
    }

    // Add others similarly...

    public function rules()
    {
        return [
            [['title', 'slug', 'content', 'type'], 'required'],
            [['content'], 'string'],
            [['title', 'slug', 'type'], 'string', 'max' => 255],
            [['slug'], 'unique'],
            ['type', 'in', 'range' => [
                self::TYPE_EXHIBITION,
                self::TYPE_ARTIST,
                self::TYPE_ARTICLE,
                self::TYPE_CATALOG,
            ]],
        ];
    }

    /**
     * Find by slug and type
     */
    public static function findBySlugAndType(string $slug, string $type): ?self
    {
        return self::findOne(['slug' => $slug, 'type' => $type]);
    }
}

Example controller action using this Post model

<?php

namespace app\controllers;

use Yii;
use yii\web\Controller;
use yii\web\NotFoundHttpException;
use app\models\Post;

class ExhibitionController extends Controller
{
    public function actionView(string $slug)
    {
        $model = Post::findBySlugAndType($slug, Post::TYPE_EXHIBITION);

        if (!$model) {
            throw new NotFoundHttpException('Exhibition not found.');
        }

        return $this->render('view', ['model' => $model]);
    }

    // other actions like index(), etc.
}

Summary

    You use one database table and ActiveRecord class for all content types.
    Controllers just filter via the type field to scope their content.
    You can keep type-specific logic, validation, and views per controller.
    Keeps your app organized and extensible.

If you want, I can help with migrations, view files, URL rules, or a demo for other controllers too!

<?php

namespace app\models;

use yii\db\ActiveRecord;

class Post extends ActiveRecord
{
    const TYPE_EXHIBITION = 'exhibition';
    const TYPE_ARTIST = 'artist';
    const TYPE_ARTICLE = 'article';
    const TYPE_CATALOG = 'catalog';

    public static function tableName()
    {
        return 'post'; // your table name
    }

    /**
     * Scope method example for Exhibitions
     */
    public static function findExhibitions()
    {
        return self::find()->where(['type' => self::TYPE_EXHIBITION]);
    }

    /**
     * Scope method example for Artists
     */
    public static function findArtists()
    {
        return self::find()->where(['type' => self::TYPE_ARTIST]);
    }

    // Add others similarly...

    public function rules()
    {
        return [
            [['title', 'slug', 'content', 'type'], 'required'],
            [['content'], 'string'],
            [['title', 'slug', 'type'], 'string', 'max' => 255],
            [['slug'], 'unique'],
            ['type', 'in', 'range' => [
                self::TYPE_EXHIBITION,
                self::TYPE_ARTIST,
                self::TYPE_ARTICLE,
                self::TYPE_CATALOG,
            ]],
        ];
    }

    /**
     * Find by slug and type
     */
    public static function findBySlugAndType(string $slug, string $type): ?self
    {
        return self::findOne(['slug' => $slug, 'type' => $type]);
    }
}

your code is flawed, you say type is a int, but you set it as a string

Good catch! However, in the code I gave, the type property is actually treated as a string — specifically, string constants like 'exhibition', 'artist', 'article', and 'catalog'.
To clarify:

    The type column in your database should be a string/varchar field, since you want to store descriptive string labels, e.g. 'exhibition', not an integer.
    In the model, the rules() and constants expect type to be a string, and the validation rule confirms it.

So, if you currently have type set as an int in your database schema, that would cause an inconsistency.

You have two options:

    Make type a string/varchar column in your post table — recommended for readability and flexibility.
    Alternatively, use integer constants for type in your code, e.g.:

const TYPE_EXHIBITION = 1;
const TYPE_ARTIST = 2;
const TYPE_ARTICLE = 3;
const TYPE_CATALOG = 4;

And then update your validation rule and queries accordingly.
Example if you want type to be an integer column:

class Post extends ActiveRecord
{
    const TYPE_EXHIBITION = 1;
    const TYPE_ARTIST = 2;
    const TYPE_ARTICLE = 3;
    const TYPE_CATALOG = 4;

    public function rules()
    {
        return [
            [['title', 'slug', 'content', 'type'], 'required'],
            [['content'], 'string'],
            [['title', 'slug'], 'string', 'max' => 255],
            [['type'], 'integer'],
            [['slug'], 'unique'],
            ['type', 'in', 'range' => [
                self::TYPE_EXHIBITION,
                self::TYPE_ARTIST,
                self::TYPE_ARTICLE,
                self::TYPE_CATALOG,
            ]],
        ];
    }

    public static function findBySlugAndType(string $slug, int $type): ?self
    {
        return self::findOne(['slug' => $slug, 'type' => $type]);
    }
}

Database column type should then be some integer type like TINYINT or INT.
Summary

    Your original code assumes string type field (varchar).
    If you prefer string identifiers (e.g. 'artist'), your DB column type must be string.
    If your DB column is integer, update your constants and code to use integers instead.

If you want, I can help you write a migration to change the type column to string or adjust the code for integer types!

"Your original code assumes string type field (varchar)." I asume nothing

You're right; I should have been clearer and not assumed. What I provided is a pattern that expects a string type column in the database for type. But whether type is string or integer entirely depends on how you design your database schema and application.

To be precise:

    If you design your database so that the type column is a string (e.g., VARCHAR(255)), then the code I provided with string constants ('exhibition', 'artist', etc.) is appropriate and consistent.
    If you prefer the type column to be an integer (e.g., TINYINT or INT), then you should change the constants in your code to integers and adjust validation rules accordingly.

How to proceed depends on your database schema choice.

If you want to use string type:

Your migration for the post table should include:

$this->createTable('post', [
    'id' => $this->primaryKey(),
    'type' => $this->string(255)->notNull(),
    // other fields like title, slug, content, etc.
]);

and your model stays as is.

If you want to use integer type:

Migration snippet:

$this->createTable('post', [
    'id' => $this->primaryKey(),
    'type' => $this->integer()->notNull(),
    // other fields
]);

and update your model constants and rules accordingly (constants as integers, validation as integer).
Summary

    The discrepancy is not a bug but a choice of database schema design.

If you'd like, I can help you generate the migration or adjust the model accordingly — just let me know which approach you prefer.

im sticking with int, it make far more sense

Got it! Using an integer for type is a common and efficient approach, especially for performance and storage optimization.

Here’s an updated version of your Post model using integer constants for type and corresponding validation:

<?php

namespace app\models;

use yii\db\ActiveRecord;

class Post extends ActiveRecord
{
    const TYPE_EXHIBITION = 1;
    const TYPE_ARTIST = 2;
    const TYPE_ARTICLE = 3;
    const TYPE_CATALOG = 4;

    public static function tableName()
    {
        return 'post';
    }

    /**
     * Scope method example for Exhibitions
     */
    public static function findExhibitions()
    {
        return self::find()->where(['type' => self::TYPE_EXHIBITION]);
    }

    /**
     * Scope method example for Artists
     */
    public static function findArtists()
    {
        return self::find()->where(['type' => self::TYPE_ARTIST]);
    }

    // Add others similarly...

    public function rules()
    {
        return [
            [['title', 'slug', 'content', 'type'], 'required'],
            [['content'], 'string'],
            [['title', 'slug'], 'string', 'max' => 255],
            [['type'], 'integer'],
            [['slug'], 'unique'],
            ['type', 'in', 'range' => [
                self::TYPE_EXHIBITION,
                self::TYPE_ARTIST,
                self::TYPE_ARTICLE,
                self::TYPE_CATALOG,
            ]],
        ];
    }

    /**
     * Find by slug and type
     */
    public static function findBySlugAndType(string $slug, int $type): ?self
    {
        return self::findOne(['slug' => $slug, 'type' => $type]);
    }
}

Database migration example

If you need a database migration to create the post table with an integer type field, here is an example:

use yii\db\Migration;

class m240624_000001_create_post_table extends Migration
{
    public function safeUp()
    {
        $this->createTable('post', [
            'id' => $this->primaryKey(),
            'type' => $this->integer()->notNull(),
            'slug' => $this->string(255)->notNull()->unique(),
            'title' => $this->string(255)->notNull(),
            'content' => $this->text()->notNull(),
            'created_at' => $this->integer()->notNull(),
            'updated_at' => $this->integer()->notNull(),
        ]);
    }

    public function safeDown()
    {
        $this->dropTable('post');
    }
}

Example controller usage

namespace app\controllers;

use Yii;
use yii\web\Controller;
use yii\web\NotFoundHttpException;
use app\models\Post;

class ExhibitionController extends Controller
{
    public function actionView(string $slug)
    {
        $model = Post::findBySlugAndType($slug, Post::TYPE_EXHIBITION);

        if (!$model) {
            throw new NotFoundHttpException('Exhibition not found.');
        }

        return $this->render('view', ['model' => $model]);
    }
}

If you want assistance generating the other controllers or help with URL rules and view templates just say!

why would i need to find by slug now? if im using type? slug could be used now properly for what the post is actually about.

Great question! Your intuition is spot on, and here’s the detailed reasoning:
Why combine slug + type in queries?

The main reason to query by both slug and type is to ensure uniqueness and avoid ambiguity if:

    Your slug values are only unique within a type, but not globally unique across all types.

    For example:
        An artist and an exhibition might share the same slug value (e.g., modern-art)
        If you only query by slug, you might fetch the wrong content.

When can you query by slug alone?

    If your application ensures global uniqueness of the slug across all post types — i.e., a single slug uniquely identifies exactly one post, regardless of type.
    This means the database enforces slug uniqueness globally (which your current rules() already does: [['slug'], 'unique']).
    In this case, you don’t need to query by type every time because slug locates the post uniquely.

What does it mean for your system design?

    Slug as a global unique identifier:
    Users visit URLs like /artwork/modern-art or /news/modern-art but the slug modern-art only exists once in the entire post table.

    Type used for categorization and filtering internally:
    Controllers still know what type they are supposed to handle and can verify that the retrieved post matches expected type, or rely on URLs and logic for enforcement.

How to handle this in code?

    Query by slug only:

$model = Post::findOne(['slug' => $slug]);
if (!$model) {
    throw new NotFoundHttpException('Content not found.');
}
// Optionally check if $model->type == expected type

    Optional validation that the post type matches the expected one:

if ($model->type != Post::TYPE_EXHIBITION) {
    throw new NotFoundHttpException('Exhibition not found.');
}

    Or, if you want strict routing, define URL rules to route only valid slugs to the right controller.

When would you still want to query by slug + type?

    When slugs are only unique per type — for example, two different posts of different types might share the same slug.
    When your app allows duplicate slugs in the database, scoped by type.
    When you want to limit queries in heavily loaded DB to a smaller subset (by type).

Summary table
Scenario 	Query by slug only? 	Query with slug + type? 	Notes
Slugs globally unique across all post types 	✅ Yes 	Optional 	Most straightforward and recommended
Slugs unique only per type 	❌ No 	✅ Yes 	Needed to disambiguate and avoid errors
You want extra strict validation in controllers 	Optional 	✅ Yes 	Controller verifies content type
Final recommendation for you

If you enforce global uniqueness of slugs (which your validation rule ['slug', 'unique'] already does):

    Query by slug only in your controller actions.
    Use the post’s type property as metadata or to customize rendering.
    Keep URLs clean and intuitive (e.g., /exhibition/modern-art uses modern-art slug only).
    Optionally, check the type after retrieving the post to avoid logical errors.

Would you like me to help refactor your controllers or URL rules accordingly?

or i guess really this is what category was for..

<?php
declare(strict_types=1);

namespace app\models;

use Yii;
use yii\db\ActiveRecord;
use yii\behaviors\TimestampBehavior;
use yii\behaviors\BlameableBehavior;
use yii\behaviors\SluggableBehavior;
//use yii\helpers\Inflector;// Note: Using SluggableBehavior instead.

use app\models\User;
use app\models\Post;
use app\helpers\PurifierHelper;

/**
* This model will handle generating slugs and managing relationships.
* This is the model class for table "{{%post_category}}".
*
* @property int $id
* @property string $title
* @property string|null $slug
* @property int|null $parent_id
* @property int $created_by
* @property int|null $updated_by
* @property int $created_at
* @property int|null $updated_at
*
* @property User $createdBy
* @property PostCategory $parent
* @property PostCategory[] $postCategories
* @property Post[] $posts
* @property User $updatedBy
*/
class PostCategory extends ActiveRecord
{
    // Declare the children property
    public array $children = [];

    public static function tableName(): string
    {
        return '{{%post_category}}';
    }
    
    public function behaviors(): array
    {
        $behaviors = [];
        
        /**
        * Timestamp Behavior
        * @url https://www.yiiframework.com/doc/api/2.0/yii-behaviors-timestampbehavior
        */
        $behaviors['timestamp'] = [
            'class' => TimestampBehavior::class,
            'attributes' => [
                    ActiveRecord::EVENT_BEFORE_INSERT => ['created_at', 'updated_at'],
                    ActiveRecord::EVENT_BEFORE_UPDATE => ['updated_at'],
            ],
            /**
            * DB Expression
            * @url https://www.yiiframework.com/doc/api/2.0/yii-db-expression
            * if you're using datetime instead of UNIX timestamp:
            *
            'value' => new Expression('NOW()'),
            'value' => date('Y-m-d H:i:s'),//*/
        ];// TimestampBehavior */
        
        /**
        * Blameable Behavior
        * @url https://www.yiiframework.com/doc/api/2.0/yii-behaviors-blameablebehavior
        */
        $behaviors['blameable'] = [
            'class' => BlameableBehavior::class,
        ];// BlameableBehavior */
        
        /**
        * Sluggable Behavior
        * @url https://www.yiiframework.com/doc/api/2.0/yii-behaviors-sluggablebehavior
        */
        $behaviors['sluggable'] = [
            'class' => SluggableBehavior::class,
            'attribute' => 'title',
            'slugAttribute' => 'slug',
            /**
            * The 'immutable' attribute tells Yii to keep the slug the same after it's first created—even 
            * if the message is updated.
            */
            'immutable' => true,
            /**
            * The 'ensureUnique' property will automatically append a unique suffix to duplicates. This 
            * makes certain that each message has a unique URL even if the message is identical. 
            */
            'ensureUnique' => true,
        ];// SluggableBehavior */
        
        return $behaviors;
    }
    
    public function rules(): array
    {
        return [
            /**
            * Rules
            * Rules are handled by either app\models\forms\** for user access validation, or
            * handled directly within the model and than view file skipping form model validation
            * for administration only.
            */
            [['title'], 'required'],
            
            [['parent_id', 'created_by', 'updated_by', 'created_at', 'updated_at'], 'integer'],
            [['title', 'slug'], 'string', 'max' => 255],
            [['slug'], 'unique'],
            
            // Ensures `parent_id` in this model refers to an existing `id` in the PostCategory model.
            [['parent_id'], 'exist', 'skipOnError' => true, 'targetClass' => self::class, 'targetAttribute' => ['parent_id' => 'id']],
            
            /**
            * BlameableBehavior
            * @url https://www.yiiframework.com/doc/api/2.0/yii-behaviors-blameablebehavior
            */
            [['created_by'], 'exist', 'skipOnError' => true, 'targetClass' => User::class, 'targetAttribute' => ['created_by' => 'id']],
            [['updated_by'], 'exist', 'skipOnError' => true, 'targetClass' => User::class, 'targetAttribute' => ['updated_by' => 'id']],
        ];
    }
    
    public function attributeLabels(): array
    {
        return [
            'id' => \Yii::t('app', 'ID'),
            'title' => \Yii::t('app', 'Title'),
            'slug' => \Yii::t('app', 'Slug'),
            'parent_id' => \Yii::t('app', 'Parent ID'),
            'created_by' => \Yii::t('app', 'Created By'),
            'updated_by' => \Yii::t('app', 'Updated By'),
            'created_at' => \Yii::t('app', 'Created At'),
            'updated_at' => \Yii::t('app', 'Updated At'),
        ];
    }
    
    /**
        * Before Save
        * @url https://www.yiiframework.com/doc/api/2.0/yii-db-baseactiverecord#beforeSave()-detail
        * @url https://www.yiiframework.com/doc/guide/2.0/en/security-authentication#implementing-identity
        * @return boolean
        *
        * Note: Do NOT add parameter(s) type hints. This method overrides an interface 
        * without type hints on parameters, adding types will cause PHP compatibility errors. 
        * Only docblock types to indicate expected input types.
        */
    public function beforeSave($insert): bool
    {
        if (!parent::beforeSave($insert))
        {
            return false;
        }
        
        // @url https://www.yiiframework.com/doc/api/2.0/yii-helpers-htmlpurifier
        $purifier = PurifierHelper::purifier();
        $this->title = $purifier->purify($this->title);
        $this->slug = $purifier->purify($this->slug);
        $this->parent_id = $purifier->purify($this->parent_id);
        
        return true;
    }
    
    /**
    * Note: Using SluggleBehavior instead of using this...
    *
    * Before Save
    * @url https://www.yiiframework.com/doc/api/2.0/yii-db-baseactiverecord#beforeSave()-detail
    * @url https://www.yiiframework.com/doc/guide/2.0/en/security-authentication#implementing-identity
    * @return boolean
    *
        * Note: Do NOT add parameter(s) type hints. This method overrides an interface 
        * without type hints on parameters, adding types will cause PHP compatibility errors. 
        * Only docblock types to indicate expected input types.
        *
    public function beforeSave($insert): bool
    {
        if (parent::beforeSave($insert))
        {
            if ($this->isNewRecord || $this->isAttributeChanged('name'))
            {
                $this->slug = $this->generateSlug($this->name);
            }
            
            return true;
        }
        
        return false;
    }
    
    // Note: Using SluggleBehavior instead of using this.
    protected function generateSlug($name): string
    {
        return Inflector::slug($name);
    }//*/
    
    /**
    * Get Parent
    * Returns the parent of a category.
    *
    * The hierarchy implemented using the adjacency list model doesn't require separate 
    * storage for children or siblings, as they are derived through queries on the same 
    * data structure. 
    *
    * Parent-Child Relationship:
    * The relationship is made explicit by having a parent_id column in the category table, 
    * which stores the ID of a category's parent. If parent_id is null, the category is a 
    * root node or top-level category.
    *
    * Children and Siblings Retrieval:
    *
    * Children: Derived by querying all categories where parent_id equals the current 
    *           category's id.
    *
    * Siblings: Derived by querying categories where parent_id equals the current category's 
    *           parent_id, excluding the category itself.
        */
    public function getParent()//: \yii\db\ActiveQuery | app\models\query\PostCategoryQuery
    {
        return $this->hasOne(self::class, ['id' => 'parent_id']);
    }
    
    /**
    * Get Children
    * Returns the direct children.
    *
    * Execute a query on the same category table to find categories where the 
    * parent_id matches the current category's id. No separate storage for children 
    * is needed because it's an associative query based on the existing data.
    */
    public function getChildren()//: \yii\db\ActiveQuery|PostCategoryQuery
    {
        return $this->hasMany(self::class, ['parent_id' => 'id']);
    }
        
    /**
    * Get Siblings
    * Fetches other categories sharing the same parent.
    *
    * Similarly, retrieving siblings involves finding other categories with the same parent_id. 
    * This, again, utilizes the existing category data without needing explicit storage.
    */
    public function getSiblings()//: \yii\db\ActiveQuery|PostCategoryQuery
    {
        return self::find()
            ->where(['parent_id' => $this->parent_id])
            ->andWhere(['!=', 'id', $this->id])
            ->all();
    }
    
    /**
    * Find Root
    */
    public static function findRoots()//: \yii\db\ActiveQuery|PostCategoryQuery
    {
        return self::find()
            ->where(['parent_id' => null])
            ->all();
    }
    
    /**
    * Find All Categories
    * @return ProductCategory[] all categories ordered by parent-child hierarchy
    *
    * This method retrieves all ProductCategory entries in the database,
    * ordered by parent_id to ensure that parent categories come before their children.
    */
    public static function findAllCategories()
    {
        return self::find()->orderBy(['parent_id' => SORT_ASC, 'id' => SORT_ASC])->all();
    }
    
    /**
    * Structures Categories
    * @param array $categories List of categories to structure.
    * @return array Structured categories in a hierarchical format.
    *
    * This method groups and nests categories ensuring a hierarchical
    * relationship with parent categories containing their children.
    */
    public static function structureCategories(array $categories)
    {
        $grouped = [];
        foreach ($categories as $category)
        {
            $grouped[$category->parent_id][] = $category;
        }
        
        return self::buildCategoryTree($grouped, null);
    }
    
    /**
    * Build Category Tree
    * @param array $grouped Categories grouped by parent_id.
    * @param int|null $parentId The current parent id for building the tree.
    * @return array A nested array of categories forming the hierarchy.
    *
    * This recursive function builds a nested array of categories
    * representing the hierarchy using parent_id relationships.
    */
    private static function buildCategoryTree(array &$grouped, int|null $parentId = null)
    {
        $result = [];
        if (isset($grouped[$parentId]))
        {
            foreach ($grouped[$parentId] as $category)
            {
                $children = self::buildCategoryTree($grouped, $category->id);
                if ($children)
                {
                    $category->children = $children;// Adding children to the category.
                }
                
                $result[] = $category;
            }
        }
        
        return $result;
    }
        
    /**
    * Flatten Categories GridView
    * @param array $categories Hierarchically structured categories.
    * @param int $level Current indentation level (used for recursion).
    * @return array Flattened categories with 'prefix' for visual indentation.
    *
    * Flattens hierarchical categories with indentation for display in GridView.
    */
    public static function flattenCategoriesGridView(array $categories, int $level = 0)
    {
        $result = [];
        foreach ($categories as $category)
        {
            // Create a copy to avoid modifying the original models.
            $categoryCopy = clone $category;
            
            $icon = '<i class="bi bi-list-nested"></i> ';
            $categoryCopy->title = str_repeat($icon, $level) . $category->title;// Indent based on level.
            
            $result[] = $categoryCopy;
            
            if (!empty($category->children))
            {
                $result = array_merge($result, self::flattenCategoriesGridView($category->children, $level + 1));
            }
        }
        
        return $result;
    }
        
    /**
    * Flatten Categories Dropdown
    * @param array $categories The hierarchical categories.
    * @param string $prefix HTML prefix using icons for indentation.
    * @return array An associative array for dropdown options with icons.
    *
    * Flattens a hierarchy of categories for a dropdown, using icons for indentation.
    *
    * If graphical representation, such as icons, is required, consider alternative
    * solutions such as:
    *   - Using libraries that enhance dropdown functionality (e.g., jQuery plugins like
    *     Select2 or Bootstrap Select) to allow richer content within dropdowns
    *   - Implementing custom dropdown menus using Bootstrap components to include HTML
    *     elements like icons, images, etc., as part of the dropdown items.
    *
    * Note: Due to limitations of standard HTML <select> elements, HTML content such as
    * icons cannot be rendered directly within <option> elements. HTML dropdowns do not
    * support rich content and will typically display such elements as raw text.
    */
    public static function flattenCategoriesDropdown(array $categories, string $prefix = '')
    {
        $list = [];
        foreach ($categories as $category)
        {
            $list[$category->id] = $prefix . $category->title;
            
            if (isset($category->children))
            {
                $list += self::flattenCategoriesDropdown($category->children, $prefix . '= ');
            }
        }
        
        return $list;
    }
    
    public function getPostCategories()//: \yii\db\ActiveQuery | app\models\query\PostCategoryQuery
    {
        return $this->hasMany(self::class, ['parent_id' => 'id']);
    }
    
    public function getPosts()//: \yii\db\ActiveQuery | app\models\query\PostQuery
    {
        return $this->hasMany(Post::class, ['category_id' => 'id']);
    }
    
    public function getCreatedBy()//: \yii\db\ActiveQuery | app\models\query\UserQuery
    {
        return $this->hasOne(User::class, ['id' => 'created_by']);
    }
    
    public function getUpdatedBy()//: \yii\db\ActiveQuery | app\models\query\UserQuery
    {
        return $this->hasOne(User::class, ['id' => 'updated_by']);
    }
    
    public static function find(): PostQuery
    {
        return new PostQuery(get_called_class());
    }
}

Yes, exactly — your PostCategory model is designed to classify and organize your posts into a hierarchical tree structure via parent_id, making it perfect for categorizing content by type or by any taxonomy you want.
How this connects to your earlier question:

    Your Post entries can be assigned a category_id referring to one of these categories.
    Categories like Exhibition, Artist, News, Catalog can be top-level or nested categories.
    Slugs in PostCategory help you build SEO-friendly URLs and allow logical grouping.
    You don't need to encode the content type in the Post model's type field if your classification is handled by category.

Benefits of using PostCategory for content type classification:

    Clean separation of content (Post) and classification/taxonomy (PostCategory).
    Easy to add new categories and subcategories without altering the post model or database schema.
    Slugs belong to categories, creating clearer URLs like /news/some-article or /artists/john-doe/artwork-title.
    Hierarchical categories allow nested groupings, e.g. exhibitions/modern-art/2024.

Your routing and controller logic might look like:

    Find a category by slug, e.g. exhibitions, artists, news.
    Within that category, find posts by slug or ID.
    Render views according to category or post context.

Example for fetching a post by category + post slug:

$category = PostCategory::find()->where(['slug' => $categorySlug])->one();
if (!$category) {
    throw new NotFoundHttpException('Category not found');
}

$post = Post::find()->where(['slug' => $postSlug, 'category_id' => $category->id])->one();
if (!$post) {
    throw new NotFoundHttpException('Post not found');
}

// Render post or category-specific view

Summary

    Your PostCategory model is a powerful mechanism to handle types/classifications cleanly.
    You can simplify or even remove the type field in Post if categories cover your needs.
    Slugs in categories and posts give flexibility and SEO-friendly URLs.
    Use the hierarchical category tree to organize your content and navigation elegantly.

If you want, I can help you draft example URL rules, controller actions, or migrations that integrate Post and PostCategory this way!

should I keep type? or did i just make it for no reason

Good question! Whether to keep the type field in your Post model really depends on your application's design goals and how you want to manage and query your content.
When to keep type:

    Quick filtering: If you want to quickly query or segment posts by broad content types without always joining or traversing categories.
    Additional metadata: type can express a higher-level classification orthogonal to categories (e.g., a post might be an article type but belong to different post categories like news or updates).
    Performance: For large datasets, filtering by an integer type column can be faster than join queries on categories.
    Simpler queries: Sometimes you only want to load all posts of a certain type regardless of category.

When it might be redundant and safe to remove type:

    If all your content classification, filtering, and business logic can be handled exclusively by PostCategory and its hierarchy.
    You never need to query posts solely by type — categories provide all necessary filtering and structure.
    You want to avoid redundancy and have a single source of truth for content classification.

Practical approach

    Keep type if:
        You foresee needing very fast, broad queries by type.
        You want an explicit, enforced content type separate from categories.
        You want type checks to enforce business rules independent of category assignment.

    Remove type if:
        You treat categories as your main content taxonomy.
        Categories are reliably hierarchical and sufficient for all your filtering.
        You prefer to avoid schema duplication and complexity.

Alternative: Use Category for type and deprecate type

If you decide categories are enough:

    Adjust your code to rely on $post->category->slug or $post->category->id for type checks.
    Modify controllers to load posts based on category.
    Remove or ignore type in your model and DB schema to avoid confusion.

Summary table
Decision 	Keep type 	Remove type
Use case 	Fast, broad filtering by content type 	Use categories exclusively
Data consistency 	Redundant if categories already cover classification 	Single source of truth classification
Code complexity 	Slightly more complex, but flexible 	Simpler, but some queries might be more complex or slower
Performance 	Potentially faster filtering for big data 	Depends on DB design and indexing
Final advice

If you're comfortable managing your hierarchy with PostCategory and it covers your current and likely future needs well, it’s fine to remove type for clarity.

If you'd like, I can help you with migration plans to drop the type column or refactor your code to rely solely on categories!

could I force category to set type? For:

Performance: For large datasets, filtering by an integer type column can be faster than join queries on categories.

Yes, you can absolutely enforce that each Category has a type (integer), and have each Post inherit its type from its assigned Category. That way:

    You keep fast type-based filtering on the post table (indexed integer column).
    You avoid duplication of classification logic (Category owns the type).
    Your Post model’s type field acts as a denormalized, indexed convenience column for performance.
    Your PostCategory model becomes the primary source of truth for type logic.

How to implement this pattern:
1. Add a type integer column to post_category table

// migration example
$this->addColumn('post_category', 'type', $this->integer()->notNull());

Define your type constants in PostCategory:

class PostCategory extends ActiveRecord
{
    const TYPE_EXHIBITION = 1;
    const TYPE_ARTIST = 2;
    const TYPE_ARTICLE = 3;
    const TYPE_CATALOG = 4;

    // other methods...

    public function getTypeLabel()
    {
        return [
            self::TYPE_EXHIBITION => 'Exhibition',
            self::TYPE_ARTIST => 'Artist',
            self::TYPE_ARTICLE => 'Article',
            self::TYPE_CATALOG => 'Catalog',
        ][$this->type] ?? 'Unknown';
    }
}

2. Add a db index on post.type column for fast querying

$this->createIndex('idx-post-type', 'post', 'type');

3. In Post model, update beforeValidate or beforeSave to sync type from category

class Post extends ActiveRecord
{
    public function beforeValidate()
    {
        if (!parent::beforeValidate()) {
            return false;
        }

        if ($this->category_id) {
            // Ensure category relation is loaded or load it
            $category = $this->category ?? PostCategory::findOne($this->category_id);

            if ($category) {
                $this->type = $category->type;
            }
        }

        return true;
    }
}

This way, anytime you save a Post, it automatically gets the right type based on its assigned Category.
4. Use type column for fast filtering in queries

// Example to find all exhibitions fast:
$exhibitionPosts = Post::find()->where(['type' => PostCategory::TYPE_EXHIBITION])->all();

Summary Benefits:
Benefit 	Explanation
Single source of classification 	Only Categories define the master type
Denormalized type in Post 	For fast indexed queries without joins
Consistency 	Post type always matches Category type
Flexibility 	Categories can have different types, and Posts follow
Notes:

    Remember to keep the type column in Post readonly or synchronized only via code so it can’t drift out of sync manually.
    Optionally, consider database constraints or triggers if you want stronger enforcement (though usually handled in app layer is enough).
    Keep indexes on both post.type and post.category_id for performance.

If you want, I can help you draft migrations and code snippets for this strategy!

so its not so much in the post model, its the postCategory model

Exactly — the authoritative place to assign and manage the post "type" should be the PostCategory model. The Post model then simply inherits or synchronizes that type based on its assigned category.
How this works conceptually:

    PostCategory defines the content type (e.g. Exhibition, Artist, Article).
    Each category record has a type column recording that type as an integer.
    Post records belong to categories via category_id.
    When a Post is created or updated, it gets its type value copied or synchronized from its PostCategory.
    Your queries can filter posts efficiently by the integer type column (indexed) without needing joins.
    Post model's type is effectively a denormalized field for performance and convenience.

Why shift the "type" responsibility to PostCategory?

    The domain classification (type) logically belongs to the category, which groups similar posts.
    Categories are fewer and more stable, easier to manage the types there.
    Posts can be moved between categories, and their type updates automatically.
    Avoids conflicting or duplicate type logic spread across posts.

Summary
Responsibility 	Model 	Role
Define content types 	PostCategory 	Holds type (int), manages classification
Classify individual content 	Post 	Holds category_id and copies category's type
Fast filtering by type 	Post (denormalized) 	Indexed type column for performance
Business logic & UI display 	Both 	Category for taxonomy, Post for content

If you want, I can help you create:

    Migration for adding type to post_category
    Migration for adding and indexing type on post
    Update your Post model’s beforeValidate() or beforeSave() to sync types automatically
    Example controller queries and best practices

Just say the word!

and this would be better performance and better handling in the controller for each type

Yes, exactly — this approach offers both better performance and cleaner controller logic:
Why better performance?

    Indexed integer column (post.type) allows very fast queries and filtering without joins.
    Querying posts by type is straightforward and efficient:

    Post::find()->where(['type' => PostCategory::TYPE_EXHIBITION])->all();

    You avoid costly JOINs with post_category every time you filter by type.
    Category hierarchy and slug logic stay in PostCategory, so you query them separately only when needed, e.g., for navigation or displaying category info.

Why better handling in controllers?

    Controllers focus on their specific content type logic, filtering by the easy-to-access type field.
    You avoid complex queries like "find post by slug and join category to check type".
    Business rules remain clear:
        Category manages taxonomy and hierarchy.
        Post manages content data and quickly accessible type.
    Makes code easier to maintain and extend without mixing taxonomy logic inside every controller.

Typical flow in your controller:

public function actionView(string $slug)
{
    $post = Post::findOne(['slug' => $slug, 'type' => PostCategory::TYPE_EXHIBITION]);

    if (!$post) {
        throw new NotFoundHttpException('Exhibition not found.');
    }

    return $this->render('view', ['model' => $post]);
}

No JOIN needed to verify type: simple, fast, and reliable.
Summary
Aspect 	Benefit
Performance 	Indexed post.type means fast queries & minimal JOINs
Maintenance 	Clear separation: category = taxonomy + type, post = content
Controller 	Simplified queries and business logic per content type
Flexibility 	Category defines type, synchronization keeps consistency

If you want, I can help with migration scripts, model code sample, or full example controller implementations for this architecture!

ok, lets do this. I need to know everything i need to change and add in order for this to work.

Great! Below is a step-by-step plan outlining everything you need to add and change to implement the approach where:

    PostCategory defines the type (an integer column).
    Post has a type integer column that is kept in sync with its category's type.
    Queries filter mostly by post.type for performance.
    Categories manage the taxonomy, hierarchy, and slugs.

Step 1: Add type column to post_category

Create a migration to add type to your post_category table. For example:

use yii\db\Migration;

class m240624_000001_add_type_to_post_category extends Migration
{
    public function safeUp()
    {
        $this->addColumn('{{%post_category}}', 'type', $this->integer()->notNull()->defaultValue(0)->after('id'));

        // Optional: Add index if you query categories by type
        $this->createIndex('idx-post_category-type', '{{%post_category}}', 'type');
    }

    public function safeDown()
    {
        $this->dropIndex('idx-post_category-type', '{{%post_category}}');
        $this->dropColumn('{{%post_category}}', 'type');
    }
}

Then, update existing categories to assign correct type values manually or via SQL.
Step 2: Add type column to post table

Create a migration to add the type integer column (denormalized for performance) to the post table, indexed for fast queries:

use yii\db\Migration;

class m240624_000002_add_type_to_post_table extends Migration
{
    public function safeUp()
    {
        $this->addColumn('{{%post}}', 'type', $this->integer()->notNull()->defaultValue(0)->after('category_id'));

        // Index for faster filtering
        $this->createIndex('idx-post-type', '{{%post}}', 'type');
    }
    
    public function safeDown()
    {
        $this->dropIndex('idx-post-type', '{{%post}}');
        $this->dropColumn('{{%post}}', 'type');
    }
}

Step 3: Update PostCategory model

Add constants for types and a type property, with any helper functions you need, e.g.:

class PostCategory extends ActiveRecord
{
    const TYPE_EXHIBITION = 1;
    const TYPE_ARTIST = 2;
    const TYPE_ARTICLE = 3;
    const TYPE_CATALOG = 4;

    public static function tableName()
    {
        return '{{%post_category}}';
    }

    public function rules()
    {
        return array_merge(parent::rules(), [
            ['type', 'required'],
            ['type', 'integer'],
            ['type', 'in', 'range' => [
                self::TYPE_EXHIBITION,
                self::TYPE_ARTIST,
                self::TYPE_ARTICLE,
                self::TYPE_CATALOG,
            ]],
        ]);
    }

    // Optionally add a method to get type labels
    public static function getTypeList(): array
    {
        return [
            self::TYPE_EXHIBITION => 'Exhibition',
            self::TYPE_ARTIST => 'Artist',
            self::TYPE_ARTICLE => 'Article',
            self::TYPE_CATALOG => 'Catalog',
        ];
    }

    public function getTypeLabel(): string
    {
        return self::getTypeList()[$this->type] ?? 'Unknown';
    }
}

Step 4: Update Post model

Add type attribute and sync it automatically from category.

class Post extends ActiveRecord
{
    public function rules()
    {
        return array_merge(parent::rules(), [
            ['type', 'integer'],
            ['type', 'default', 'value' => 0],
        ]);
    }

    public function beforeValidate()
    {
        if (!parent::beforeValidate()) {
            return false;
        }

        // Sync type from category if category_id set
        if ($this->category_id) {
            $category = $this->category ?? PostCategory::findOne($this->category_id);
            if ($category) {
                $this->type = $category->type;
            }
        }

        return true;
    }

    /**
     * Relation to PostCategory
     */
    public function getCategory()
    {
        return $this->hasOne(PostCategory::class, ['id' => 'category_id']);
    }
}

Step 5: Update your CRUD/forms/views

    Whenever you create/edit a Post and change its category_id, the type will update automatically.
    Do NOT manually edit type in forms. You can make it safe only for internal sync.

Step 6: Controllers — filter by type

Example for ExhibitionController:

class ExhibitionController extends Controller
{
    public function actionView(string $slug)
    {
        $model = Post::find()->where(['slug' => $slug, 'type' => PostCategory::TYPE_EXHIBITION])->one();

        if (!$model

finish this