npm package: @jatorresdev/angular2-jsonapi
Description: A lightweight Angular 2+ adapter for JSON API
Author: Daniele Ghidoli
Latest version: 9.0.3

# Angular 2 JSON API

A lightweight Angular 2 adapter for [JSON API](http://jsonapi.org/)

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## Table of Contents
- [Introduction](#Introduction)
- [Installation](#installation)
- [Usage](#usage)
    - [Configuration](#configuration)
    - [Finding Records](#finding-records)
        - [Querying for Multiple Records](#querying-for-multiple-records)
        - [Retrieving a Single Record](#retrieving-a-single-record)
    - [Creating, Updating and Deleting](#creating-updating-and-deleting)
        - [Creating Records](#creating-records)
        - [Updating Records](#updating-records)
        - [Persisting Records](#persisting-records)
        - [Deleting Records](#deleting-records)
    - [Relationships](#relationships)
    - [Metadata](#metadata)
    - [Custom Headers](#custom-headers)
    - [Error handling](#error-handling)
    - [Dates](#dates)
- [Development](#development)
- [Additional tools](#additional-tools)
- [License](#licence)

## Introduction
Why this library? Because [JSON API](http://jsonapi.org/) is an awesome standard, but the responses that you get and the way to interact with endpoints are not really easy and directly consumable from Angular.

Moreover, using Angular2 and Typescript, we like to interact with classes and models, not with bare JSONs. Thanks to this library, you will be able to map all your data into models and relationships like these:

```javascript
[
    Post{
        id: 1,
        title: 'My post',
        content: 'My content',
        comments: [
            Comment{
                id: 1,
                // ...
            },
            Comment{
                id: 2,
                // ...
            }
        ]
    },
    // ...
]
```


## Installation

To install this library, run:
```bash
$ npm install angular2-jsonapi --save
```

Add the `JsonApiModule` to your app module imports:
```typescript
import { JsonApiModule } from 'angular2-jsonapi';

@NgModule({
  imports: [
    BrowserModule,
    JsonApiModule
  ],
  declarations: [
    AppComponent
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }
```

## Usage

### Configuration

Firstly, create your `Datastore` service:
- Extend the `JsonApiDatastore` class
- Decorate it with `@JsonApiDatastoreConfig`, set the `baseUrl` for your APIs and map your models (Optional: you can set `apiVersion`, `baseUrl` will be suffixed with it)
- Pass the `HttpClient` depencency to the parent constructor.

```typescript
import { JsonApiDatastoreConfig, JsonApiDatastore, DatastoreConfig } from 'angular2-jsonapi';

const config: DatastoreConfig = {
  baseUrl: 'http://localhost:8000/v1/',
  models: {
    posts: Post,
    comments: Comment,
    users: User
  }
}

@Injectable()
@JsonApiDatastoreConfig(config)
export class Datastore extends JsonApiDatastore {

    constructor(http: HttpClient) {
        super(http);
    }

}
```

Then set up your models:
- Extend the `JsonApiModel` class
- Decorate it with `@JsonApiModelConfig`, passing the `type`
- Decorate the class properties with `@Attribute`
- Decorate the relationships attributes with `@HasMany` and `@BelongsTo`
- (optional) Define your [Metadata](#metadata)

```typescript
import { JsonApiModelConfig, JsonApiModel, Attribute, HasMany, BelongsTo } from 'angular2-jsonapi';

@JsonApiModelConfig({
    type: 'posts'
})
export class Post extends JsonApiModel {

    @Attribute()
    title: string;

    @Attribute()
    content: string;

    @Attribute({ serializedName: 'created-at' })
    createdAt: Date;

    @HasMany()
    comments: Comment[];
}

@JsonApiModelConfig({
    type: 'comments'
})
export class Comment extends JsonApiModel {

    @Attribute()
    title: string;

    @Attribute()
    created_at: Date;

    @BelongsTo()
    post: Post;

    @BelongsTo()
    user: User;
}

@JsonApiModelConfig({
    type: 'users'
})
export class User extends JsonApiModel {

    @Attribute()
    name: string;
    // ...
}
```

### Finding Records

#### Querying for Multiple Records

Now, you can use your `Datastore` in order to query your API with the `findAll()` method:
- The first argument is the type of object you want to query.
- The second argument is the list of params: write them in JSON format and they will be serialized.
- The returned value is a document which gives access to the metdata and the models.
```typescript
// ...
constructor(private datastore: Datastore) { }

getPosts(){
    this.datastore.findAll(Post, {
        page: { size: 10, number: 1 },
        filter: {
          title: 'My Post',
        },
    }).subscribe(
        (posts: JsonApiQueryData<Post>) => console.log(posts.getModels())
    );
}
```

Use `peekAll()` to retrieve all of the records for a given type that are already loaded into the store, without making a network request:

```typescript
let posts = this.datastore.peekAll(Post);
```


#### Retrieving a Single Record

Use `findRecord()` to retrieve a record by its type and ID:

```typescript
this.datastore.findRecord(Post, '1').subscribe(
    (post: Post) => console.log(post)
);
```

Use `peekRecord()` to retrieve a record by its type and ID, without making a network request. This will return the record only if it is already present in the store:

```typescript
let post = this.datastore.peekRecord(Post, '1');
```

### Creating, Updating and Deleting

#### Creating Records

You can create records by calling the `createRecord()` method on the datastore:
- The first argument is the type of object you want to create.
- The second is a JSON with the object attributes.

```typescript
this.datastore.createRecord(Post, {
    title: 'My post',
    content: 'My content'
});
```

#### Updating Records

Making changes to records is as simple as setting the attribute you want to change:

```typescript
this.datastore.findRecord(Post, '1').subscribe(
    (post: Post) => {
        post.title = 'New title';
    }
);
```

#### Persisting Records

Records are persisted on a per-instance basis. Call `save()` on any instance of `JsonApiModel` and it will make a network request.

The library takes care of tracking the state of each record for you, so that newly created records are treated differently from existing records when saving.

Newly created records will be `POST`ed:

```typescript
let post = this.datastore.createRecord(Post, {
    title: 'My post',
    content: 'My content'
});

post.save().subscribe();  // => POST to '/posts'
```

Records that already exist on the backend are updated using the HTTP `PATCH` verb:

```typescript
this.datastore.findRecord(Post, '1').subscribe(
    (post: Post) => {
        post.title = 'New title';
        post.save().subscribe();  // => PATCH to '/posts/1'
    }
);
```

The `save()` method will return an `Observer` that you need to subscribe:

```typescript
post.save().subscribe(
    (post: Post) => console.log(post)
);
```

**Note**: always remember to call the `subscribe()` method, even if you are not interested in doing something with the response. Since the `http` method return a [cold Observable](https://github.com/Reactive-Extensions/RxJS/blob/master/doc/gettingstarted/creating.md#cold-vs-hot-observables), the request won't go out until something subscribes to the observable.

You can tell if a record has outstanding changes that have not yet been saved by checking its `hasDirtyAttributes` property.

At this point, you can either persist your changes via `save()` or you can roll back your changes. Calling `rollbackAttributes()` for a saved record reverts all the dirty attributes to their original value.

```typescript
this.datastore.findRecord(Post, '1').subscribe(
    (post: Post) => {
        console.log(post.title);                // => 'Old title'
        console.log(post.hasDirtyAttributes);   // => false
        post.title = 'New title';
        console.log(post.hasDirtyAttributes);   // => true
        post.rollbackAttributes();
        console.log(post.hasDirtyAttributes);   // => false
        console.log(post.title);                // => 'Old title'
    }
);
```

#### Deleting Records

For deleting a record, just call the datastore's method `deleteRecord()`, passing the type and the id of the record:

```typescript
this.datastore.deleteRecord(Post, '1').subscribe(() => {
    // deleted!
});
```

### Relationships

#### Querying records

In order to query an object including its relationships, you can pass in its options the attribute name you want to load with the relationships:

```typescript
this.datastore.findAll(Post, {
    page: { size: 10, number: 1},
    include: 'comments'
}).subscribe(
    (document) => {
        console.log(document.getMeta()); // metadata
        console.log(document.getModels()); // models
    }
);
```

The same, if you want to include relationships when finding a record:

```typescript
this.datastore.findRecord(Post, '1', {
    include: 'comments,comments.user'
}).subscribe(
    (post: Post) => console.log(post)
);
```

The library will try to resolve relationships on infinite levels connecting nested objects by reference. So that you can have a `Post`, with a list of `Comment`s, that have a `User` that has `Post`s, that have `Comment`s... etc.

**Note**: If you `include` multiple relationships, **do not** use whitespaces in the `include` string (e.g. `comments, comments.user`) as those will be encoded to `%20` and this results in a broken URL.

#### Creating Records

If the object you want to create has a **one-to-many** relationship, you can do this:

```typescript
let post = this.datastore.peekRecord(Post, '1');
let comment = this.datastore.createRecord(Comment, {
    title: 'My comment',
    post: post
});
comment.save().subscribe();
```

The library will do its best to discover which relationships map to one another. In the code above, for example, setting the `comment` relationship with the `post` will update the `post.comments` array, automatically adding the `comment` object!

If you want to include a relationship when creating a record to have it parsed in the response, you can pass the `params` object to the `save()` method:

```typescript
comment.save({
    include: 'user'
}).subscribe(
    (comment: Comment) => console.log(comment)
);
```

#### Updating Records

You can also update an object that comes from a relationship:

```typescript
this.datastore.findRecord(Post, '1', {
    include: 'comments'
}).subscribe(
    (post: Post) => {
        let comment: Comment = post.comments[0];
        comment.title = 'Cool';
        comment.save().subscribe((comment: Comment) => {
            console.log(comment);
        });
    }
);
```

### Metadata
Metadata such as links or data for pagination purposes can also be included in the result.

For each model a specific MetadataModel can be defined. To do this, the class name needs to be added in the ModelConfig.

If no MetadataModel is explicitly defined, the default one will be used, which contains an array of links and `meta` property.
```
@JsonApiModelConfig({
    type: 'deals',
    meta: JsonApiMetaModel
})
export class Deal extends JsonApiModel
```

An instance of a class provided in `meta` property will get the whole response in a constructor.

### Datastore config

Datastore config can be specified through the `JsonApiDatastoreConfig` decorator and/or by setting a `config` variable of the `Datastore` class. If an option is specified in both objects, a value from `config` variable will be taken into account.

```typescript
@JsonApiDatastoreConfig(config: DatastoreConfig)
export class Datastore extends JsonApiDatastore {
    private customConfig: DatastoreConfig = {
        baseUrl: 'http://something.com'
    }

    constructor() {
        this.config = this.customConfig;
    }
}
```

`config`:

* `models` - all the models which will be stored in the datastore
* `baseUrl` - base API URL
* `apiVersion` - optional, a string which will be appended to the baseUrl
* `overrides` - used for overriding internal methods to achive custom functionalities

##### Overrides

* `getDirtyAttributes` - determines which model attributes are dirty
* `toQueryString` - transforms query parameters to a query string


### Model config

```typescript
@JsonApiModelConfig(options: ModelOptions)
export class Post extends JsonApiModel { }
```

`options`:

* `type`
* `baseUrl` - if not specified, the global `baseUrl` will be used
* `apiVersion` - if not specified, the global `apiVersion` will be used
* `modelEndpointUrl` - if not specified, `type` will be used instead
* `meta` - optional, metadata model

### Decorators

#### Model decorators

* `Attribute(options: AttributeDecoratorOptions)`

    * `AttributeDecoratorOptions`:

        * `converter`, optional, must implement `PropertyConverter` interface
        * `serializedName`, optional

### Custom Headers

By default, the library adds these headers, according to the [JSON API MIME Types](http://jsonapi.org/#mime-types):

```
Accept: application/vnd.api+json
Content-Type: application/vnd.api+json
```

You can also add your custom headers to be appended to each http call:

```typescript
this.datastore.headers = new HttpHeaders({'Authorization': 'Bearer ' + accessToken});
```

Or you can pass the headers as last argument of any datastore call method:

```typescript
this.datastore.findAll(Post, {
    include: 'comments'
}, new HttpHeaders({'Authorization': 'Bearer ' + accessToken}));
```

and in the `save()` method:

```typescript
post.save({}, new HttpHeaders({'Authorization': 'Bearer ' + accessToken})).subscribe();
```

### Custom request options

You can add your custom request options to be appended to each http call:

```typescript
this.datastore.requestOptions = {
    withCredentials: false,
    myOption: 123
}
```

### Error handling

Error handling is done in the `subscribe` method of the returned Observables.
If your server returns valid [JSON API Error Objects](http://jsonapi.org/format/#error-objects) you can access them in your onError method:

```typescript
import {ErrorResponse} from "angular2-jsonapi";

...

this.datastore.findAll(Post).subscribe(
    (posts: Post[]) => console.log(posts),
    (errorResponse) => {
        if (errorResponse instanceof ErrorResponse) {
              // do something with errorResponse
              console.log(errorResponse.errors);
        }
    }
);
```

It's also possible to handle errors for all requests by overriding `handleError(error: any): Observable` in the datastore.

### Dates

The library will automatically transform date values into `Date` objects and it will serialize them when sending to the server. In order to do that, remember to set the type of the corresponding attribute as `Date`:

```typescript
@JsonApiModelConfig({
    type: 'posts'
})
export class Post extends JsonApiModel {

    // ...

    @Attribute()
    created_at: Date;

}
```

Moreover, it should be noted that the following assumptions have been made:
- Dates are expected to be received in one of the ISO 8601 formats, as per the [JSON API spec recommendation](http://jsonapi.org/recommendations/#date-and-time-fields);
- Dates are always sent in full ISO 8601 format, with local timezone and without milliseconds (example: `2001-02-03T14:05:06+07:00`).


## Development

To generate all `*.js`, `*.js.map` and `*.d.ts` files:

```bash
$ npm run build
```

To lint all `*.ts` files:

```bash
$ npm run lint
```

## Additional tools
* Gem for generating the model definitions based on active model serializers: https://github.com/oncore-education/jsonapi_models

## Thanks

This library is inspired by the draft of [this never implemented library](https://github.com/beauby/angular2-jsonapi).

## License

MIT © [Daniele Ghidoli](http://danieleghidoli.it)