npm package: @nampham0494/prisma-generator-nestjs-dto
Description: Generates DTO and Entity classes from Prisma Schema for NestJS
Latest version: 1.0.1

# Prisma Generator NestJS DTO

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[![License](https://img.shields.io/github/license/vegardit/prisma-generator-nestjs-dto.svg?label=license)](#license)

1. [What is it?](#what-is-it)
1. [Usage](#usage)
1. [Annotations](#annotations)
1. [Example](#example)
1. [Principles](#principles)
1. [License](#license)

## <a name="what-is-it"></a>What is it?

Generates `ConnectDTO`, `CreateDTO`, `UpdateDTO`, and `Entity` classes for models in your Prisma Schema. This is useful if you want to leverage [OpenAPI](https://docs.nestjs.com/openapi/introduction) in your [NestJS](https://nestjs.com/) application - but also helps with GraphQL resources as well). NestJS Swagger requires input parameters in [controllers to be described through classes](https://docs.nestjs.com/openapi/types-and-parameters) because it leverages TypeScript's emitted metadata and `Reflection` to generate models/components for the OpenAPI spec. It does the same for response models/components on your controller methods.

These classes can also be used with the built-in [ValidationPipe](https://docs.nestjs.com/techniques/validation#using-the-built-in-validationpipe) and [Serialization](https://docs.nestjs.com/techniques/serialization).

## <a name="usage"></a>Usage?

```sh
npm install --save-dev @vegardit/prisma-generator-nestjs-dto
```

```prisma
generator nestjsDto {
  provider                        = "prisma-generator-nestjs-dto"
  output                          = "../src/generated/nestjs-dto"
  outputToNestJsResourceStructure = "false"
  exportRelationModifierClasses   = "true"
  reExport                        = "false"
  createDtoPrefix                 = "Create"
  updateDtoPrefix                 = "Update"
  dtoSuffix                       = "Dto"
  entityPrefix                    = ""
  entitySuffix                    = ""
  fileNamingStyle                 = "camel"
}
```

### Parameters

All parameters are optional.

- [`output`]: (default: `"../src/generated/nestjs-dto"`) - output path relative to your `schema.prisma` file
- [`outputToNestJsResourceStructure`]: (default: `"false"`) - writes `dto`s and `entities` to subfolders aligned with [NestJS CRUD generator](https://docs.nestjs.com/recipes/crud-generator). Resource module name is derived from lower-cased model name in `schema.prisma`
- [`exportRelationModifierClasses`]: (default: `"true"`) - Should extra classes generated for relationship field operations on DTOs be exported?
- [`reExport`]: (default: `false`) - Should an index.ts be created for every folder?
- [`createDtoPrefix`]: (default: `"Create"`) - phrase to prefix every `CreateDTO` class with
- [`updateDtoPrefix`]: (default: `"Update"`) - phrase to prefix every `UpdateDTO` class with
- [`dtoSuffix`]: (default: `"Dto"`) - phrase to suffix every `CreateDTO` and `UpdateDTO` class with
- [`entityPrefix`]: (default: `""`) - phrase to prefix every `Entity` class with
- [`entitySuffix`]: (default: `""`) - phrase to suffix every `Entity` class with
- [`fileNamingStyle`]: (default: `"camel"`) - how to name generated files. Valid choices are `"camel"`, `"pascal"`, `"kebab"` and `"snake"`.

## <a name="annotations"></a>Annotations

Annotations provide additional information to help this generator understand your intentions. They are applied as [tripple slash comments](https://www.prisma.io/docs/concepts/components/prisma-schema#comments) to a field node in your Prisma Schema. You can apply multiple annotations to the same field.

```prisma
model Post {
  /// @DtoCreateOptional
  /// @DtoUpdateHidden
  createdAt   DateTime @default(now())
}
```

- @DtoReadOnly - omits field in `CreateDTO` and `UpdateDTO`
- @DtoEntityHidden - omits field in `Entity`
- @DtoCreateOptional - adds field **optionally** to `CreateDTO` - useful for fields that would otherwise be omitted (e.g. `@id`, `@updatedAt`)
- @DtoUpdateOptional- adds field **optionally** to `UpdateDTO` - useful for fields that would otherwise be omitted (e.g. `@id`, `@updatedAt`)
- @DtoRelationRequired - marks relation **required** in `Entity` although it's optional in PrismaSchema - useful when you don't want (SQL) `ON DELETE CASCADE` behavior - but your logical data schema sees this relation as required  
  (**Note**: becomes obsolete once [referentialActions](https://github.com/prisma/prisma/issues/7816) are released and stable)
- @DtoRelationCanCreateOnCreate - adds [create](https://www.prisma.io/docs/concepts/components/prisma-client/relation-queries#create-a-related-record) option on a relation field in the generated `CreateDTO` - useful when you want to allow to create related model instances
- @DtoRelationCanConnectOnCreate - adds [connect](https://www.prisma.io/docs/concepts/components/prisma-client/relation-queries#connect-an-existing-record) option on a relation field in the generated `CreateDTO` - useful when you want/need to connect to an existing related instance
- @DtoRelationCanCreateOnUpdate - adds [create](https://www.prisma.io/docs/concepts/components/prisma-client/relation-queries#create-a-related-record) option on a relation field in the generated `UpdateDTO` - useful when you want to allow to create related model instances
- @DtoRelationCanConnectOnUpdate - adds [connect](https://www.prisma.io/docs/concepts/components/prisma-client/relation-queries#connect-an-existing-record) option on a relation field in the generated `UpdateDTO` - useful when you want/need to connect to an existing related instance

## <a name="example"></a>Example

<details>
  <summary>Prisma Schema</summary>
  
  ```prisma

generator nestjsDto {
provider = "prisma-generator-nestjs-dto"
output = "../src"
outputToNestJsResourceStructure = "true"
}

model Question {
id String @id @default(dbgenerated("gen_random_uuid()")) @db.Uuid
/// @DtoReadOnly
createdAt DateTime @default(now())
/// @DtoRelationRequired
createdBy User? @relation("CreatedQuestions", fields: [createdById], references: [id])
createdById String? @db.Uuid
updatedAt DateTime @updatedAt
/// @DtoRelationRequired
updatedBy User? @relation("UpdatedQuestions", fields: [updatedById], references: [id])
updatedById String? @db.Uuid

    /// @DtoRelationRequired
    /// @DtoRelationCanConnectOnCreate
    category   Category? @relation(fields: [categoryId], references: [id])
    categoryId String?   @db.Uuid

    /// @DtoCreateOptional
    /// @DtoRelationCanCreateOnCreate
    /// @DtoRelationCanConnectOnCreate
    /// @DtoRelationCanCreateOnUpdate
    /// @DtoRelationCanConnectOnUpdate
    tags Tag[]

    title     String
    content   String
    responses Response[]

}

````

</details>

<details>
<summary>Generated results</summary>

```ts
// src/question/dto/connect-question.dto.ts
export class ConnectQuestionDto {
  id: string;
}
````

```ts
// src/question/dto/create-question.dto.ts
import { ApiExtraModels } from '@nestjs/swagger';
import { ConnectCategoryDto } from '../../category/dto/connect-category.dto';
import { CreateTagDto } from '../../tag/dto/create-tag.dto';
import { ConnectTagDto } from '../../tag/dto/connect-tag.dto';

export class CreateQuestionCategoryRelationInputDto {
  connect: ConnectCategoryDto;
}
export class CreateQuestionTagsRelationInputDto {
  create?: CreateTagDto[];
  connect?: ConnectTagDto[];
}

@ApiExtraModels(
  ConnectCategoryDto,
  CreateQuestionCategoryRelationInputDto,
  CreateTagDto,
  ConnectTagDto,
  CreateQuestionTagsRelationInputDto,
)
export class CreateQuestionDto {
  category: CreateQuestionCategoryRelationInputDto;
  tags?: CreateQuestionTagsRelationInputDto;
  title: string;
  content: string;
}
```

```ts
// src/question/dto/update-question.dto.ts
import { ApiExtraModels } from '@nestjs/swagger';
import { CreateTagDto } from '../../tag/dto/create-tag.dto';
import { ConnectTagDto } from '../../tag/dto/connect-tag.dto';

export class UpdateQuestionTagsRelationInputDto {
  create?: CreateTagDto[];
  connect?: ConnectTagDto[];
}

@ApiExtraModels(CreateTagDto, ConnectTagDto, UpdateQuestionTagsRelationInputDto)
export class UpdateQuestionDto {
  tags?: UpdateQuestionTagsRelationInputDto;
  title?: string;
  content?: string;
}
```

```ts
// src/question/entities/question.entity.ts
import { User } from '../../user/entities/user.entity';
import { Category } from '../../category/entities/category.entity';
import { Tag } from '../../tag/entities/tag.entity';
import { Response } from '../../response/entities/response.entity';

export class Question {
  id: string;
  createdAt: Date;
  createdBy?: User;
  createdById: string;
  updatedAt: Date;
  updatedBy?: User;
  updatedById: string;
  category?: Category;
  categoryId: string;
  tags?: Tag[];
  title: string;
  content: string;
  responses?: Response[];
}
```

</details>

## <a name="principles"></a>Principles

Generally we read field properties from the `DMMF.Field` information provided by `@prisma/generator-helper`. Since a few scenarios don't become quite clear from that, we also check for additional [annotations](#annotations) (or `decorators`) in a field's `documentation` (that is anything provided as a [tripple slash comments](https://www.prisma.io/docs/concepts/components/prisma-schema#comments) for that field in your `prisma.schema`).

Initially, we wanted `DTO` classes to `implement Prisma.<ModelName><(Create|Update)>Input` but that turned out to conflict with **required** relation fields.

### ConnectDTO

This kind of DTO represents the structure of input-data to expect from 'outside' (e.g. REST API consumer) when attempting to `connect` to a model through a relation field.

A `Model`s `ConnectDTO` class is composed from a unique'd list of `isId` and `isUnique` scalar fields. If the `ConnectDTO` class has exactly one property, the property is marked as required. If there are more than one properties, all properties are optional (since setting a single one of them is already sufficient for a unique query) - you must however specify at least one property.

`ConnectDTO`s are used for relation fields in `CreateDTO`s and `UpdateDTO`s.

### CreateDTO

This kind of DTO represents the structure of input-data to expect from 'outside' (e.g. REST API consumer) when attempting to `create` a new instance of a `Model`.
Typically the requirements for database schema differ from what we want to allow users to do.
As an example (and this is the opinion represented in this generator), we don't think that relation scalar fields should be exposed to users for `create`, `update`, or `delete` activities (btw. TypeScript types generated in PrismaClient exclude these fields as well). If however, your schema defines a required relation, creating an entity of that Model would become quite difficult without the relation data.
In some cases you can derive information regarding related instances from context (e.g. HTTP path on the rest endpoint `/api/post/:postid/comment` to create a `Comment` with relation to a `Post`). For all other cases, we have the

- `@DtoRelationCanCreateOnCreate`
- `@DtoRelationCanConnectOnCreate`
- `@DtoRelationCanCreateOnUpdate`
- `@DtoRelationCanConnectOnUpdate`

[annotations](#annotations) that generate corresponding input properties on `CreateDTO` and `UpdateDTO` (optional or required - depending on the nature of the relation).

When generating a `Model`s `CreateDTO` class, field that meet any of the following conditions are omitted (**order matters**):

- `isReadOnly` OR is annotated with `@DtoReadOnly` (_Note:_ this apparently includes relation scalar fields)
- field represents a relation (`field.kind === 'object'`) and is not annotated with `@DtoRelationCanCreateOnCreate` or `@DtoRelationCanConnectOnCreate`
- field is a [relation scalar](https://www.prisma.io/docs/concepts/components/prisma-schema/relations/#annotated-relation-fields-and-relation-scalar-fields)
- field is not annotated with `@DtoCreateOptional` AND
  - `isId && hasDefaultValue` (id fields are not supposed to be provided by the user)
  - `isUpdatedAt` ([Prisma](https://www.prisma.io/docs/reference/api-reference/prisma-schema-reference#updatedat) will inject value)
  - `isRequired && hasDefaultValue` (for schema-required fields that fallback to a default value when empty. Think: `createdAt` timestamps with `@default(now())` (see [now()](https://www.prisma.io/docs/reference/api-reference/prisma-schema-reference#now)))

### UpdateDTO

When generating a `Model`s `UpdateDTO` class, field that meet any of the following conditions are omitted (**order matters**):

- field is annotated with `@DtoUpdateOptional`
- `isReadOnly` OR is annotated with `@DtoReadOnly` (_Note:_ this apparently includes relation scalar fields)
- `isId` (id fields are not supposed to be updated by the user)
- field represents a relation (`field.kind === 'object'`) and is not annotated with `@DtoRelationCanCreateOnUpdate` or `@DtoRelationCanConnectOnUpdate`
- field is a [relation scalar](https://www.prisma.io/docs/concepts/components/prisma-schema/relations/#annotated-relation-fields-and-relation-scalar-fields)
- field is not annotated with `@DtoUpdateOptional` AND
  - `isId` (id fields are not supposed to be updated by the user)
  - `isUpdatedAt` ([Prisma](https://www.prisma.io/docs/reference/api-reference/prisma-schema-reference#updatedat) will inject value)
  - `isRequired && hasDefaultValue` (for schema-required fields that fallback to a default value when empty. Think: `createdAt` timestamps with `@default(now())` (see [now()](https://www.prisma.io/docs/reference/api-reference/prisma-schema-reference#now)))

### Entity

When generating a `Model`s `Entity` class, only fields annotated with `@DtoEntityHidden` are omitted.
All other fields are only manipulated regarding their `isRequired` and `isNullable` flags.

By default, every scalar field in an entity is `required` meaning it doesn't get the TypeScript "optional member flag" `?` next to it's name. Fields that are marked as optional in PrismaSchema are treated as `nullable` - meaning their TypeScript type is a union of `field.type` and `null` (e.g. `string | null`).

Relation and [relation scalar](https://www.prisma.io/docs/concepts/components/prisma-schema/relations/#annotated-relation-fields-and-relation-scalar-fields) fields are treated differently. If you don't specifically `include` a relation in your query, those fields will not exist in the response.

- every relation field is always optional (`isRequired = false`)
- relations are nullable except when
  - the relation field is a one-to-many or many-to-many (i.e. list) type (would return empty array if no related records found)
  - the relation was originally flagged as required (`isRequired = true`)
  - the relation field is annotated with `@DtoRelationRequired` (do this when you mark a relation as optional in PrismaSchema because you don't want (SQL) `ON DELETE CASCADE` behavior - but your logical data schema sees this relation as required)

## <a name="license"></a>License

All files are released under the [Apache License 2.0](https://github.com/vegardit/prisma-generator-nestjs-dto/blob/master/LICENSE).