# Nest.js Paginate

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Pagination and filtering helper method for TypeORM repositories or query builders using [Nest.js](https://nestjs.com/) framework.

- Pagination conforms to [JSON:API](https://jsonapi.org/)
- Sort by multiple columns
- Search across columns
- Filter using operators (`$eq`, `$not`, `$null`, `$in`, `$gt`, `$gte`, `$lt`, `$lte`, `$btw`)
- Include relations

## Installation

```
npm install nestjs-paginate
```

## Usage

### Example

The following code exposes a route that can be utilized like so:

#### Endpoint

```url
http://localhost:3000/cats?limit=5&page=2&sortBy=color:DESC&search=i&filter.age=$gte:3
```

#### Result

```json
{
  "data": [
    {
      "id": 4,
      "name": "George",
      "color": "white",
      "age": 3
    },
    {
      "id": 5,
      "name": "Leche",
      "color": "white",
      "age": 6
    },
    {
      "id": 2,
      "name": "Garfield",
      "color": "ginger",
      "age": 4
    },
    {
      "id": 1,
      "name": "Milo",
      "color": "brown",
      "age": 5
    },
    {
      "id": 3,
      "name": "Kitty",
      "color": "black",
      "age": 3
    }
  ],
  "meta": {
    "itemsPerPage": 5,
    "totalItems": 12,
    "currentPage": 2,
    "totalPages": 3,
    "sortBy": [["color", "DESC"]],
    "search": "i",
    "filter": {
      "age": "$gte:3"
    }
  },
  "links": {
    "first": "http://localhost:3000/cats?limit=5&page=1&sortBy=color:DESC&search=i&filter.age=$gte:3",
    "previous": "http://localhost:3000/cats?limit=5&page=1&sortBy=color:DESC&search=i&filter.age=$gte:3",
    "current": "http://localhost:3000/cats?limit=5&page=2&sortBy=color:DESC&search=i&filter.age=$gte:3",
    "next": "http://localhost:3000/cats?limit=5&page=3&sortBy=color:DESC&search=i&filter.age=$gte:3",
    "last": "http://localhost:3000/cats?limit=5&page=3&sortBy=color:DESC&search=i&filter.age=$gte:3"
  }
}
```

#### Code

```ts
import { Controller, Injectable, Get } from '@nestjs/common'
import { InjectRepository } from '@nestjs/typeorm'
import { FilterOperator, Paginate, PaginateQuery, paginate, Paginated } from 'nestjs-paginate'
import { Repository, Entity, PrimaryGeneratedColumn, Column } from 'typeorm'

@Entity()
export class CatEntity {
  @PrimaryGeneratedColumn()
  id: number

  @Column('text')
  name: string

  @Column('text')
  color: string

  @Column('int')
  age: number
}

@Injectable()
export class CatsService {
  constructor(
    @InjectRepository(CatEntity)
    private readonly catsRepository: Repository<CatEntity>
  ) {}

  public findAll(query: PaginateQuery): Promise<Paginated<CatEntity>> {
    return paginate(query, this.catsRepository, {
      sortableColumns: ['id', 'name', 'color', 'age'],
      searchableColumns: ['name', 'color', 'age'],
      defaultSortBy: [['id', 'DESC']],
      filterableColumns: {
        age: [FilterOperator.GTE, FilterOperator.LTE],
      },
    })
  }
}

@Controller('cats')
export class CatsController {
  constructor(private readonly catsService: CatsService) {}

  @Get()
  public findAll(@Paginate() query: PaginateQuery): Promise<Paginated<CatEntity>> {
    return this.catsService.findAll(query)
  }
}
```

### Config

```ts
const paginateConfig: PaginateConfig<CatEntity> {
  /**
   * Required: true (must have a minimum of one column)
   * Type: (keyof CatEntity)[]
   * Description: These are the columns that are valid to be sorted by.
   */
  sortableColumns: ['id', 'name', 'color'],

  /**
   * Required: false
   * Type: [keyof CatEntity, 'ASC' | 'DESC'][]
   * Default: [[sortableColumns[0], 'ASC]]
   * Description: The order to display the sorted entities.
   */
  defaultSortBy: [['name', 'DESC']],

  /**
   * Required: false
   * Type: (keyof CatEntity)[]
   * Description: These columns will be searched through when using the search query
   * param. Limit search scope further by using `searchBy` query param.
   */
  searchableColumns: ['name', 'color'],

  /**
   * Required: false
   * Type: TypeORM partial selection
   * Default: None
   * https://typeorm.io/select-query-builder#partial-selection
   */
  select: ['name', 'color'],

  /**
   * Required: false
   * Type: number
   * Default: 100
   * Description: The maximum amount of entities to return per page.
   */
  maxLimit: 20,

  /**
   * Required: false
   * Type: number
   * Default: 20
   */
  defaultLimit: 50,

  /**
   * Required: false
   * Type: TypeORM find options
   * Default: None
   * https://typeorm.io/#/find-optionsfind-options.md
   */
  where: { color: 'ginger' },

  /**
   * Required: false
   * Type: { [key in CatEntity]?: FilterOperator[] } - Operators based on TypeORM find operators
   * Default: None
   * https://typeorm.io/#/find-options/advanced-options
   */
  filterableColumns: { age: [FilterOperator.EQ, FilterOperator.IN] },

  /**
   * Required: false
   * Type: RelationColumn<CatEntity>
   * Description: Indicates what relations of entity should be loaded.
   */
  relations: [],

  /**
   * Required: false
   * Type: boolean
   * Description: Disables the global condition of "non-deleted" for the entity with delete date columns.
   * https://typeorm.io/select-query-builder#querying-deleted-rows
   */
  withDeleted: false,
}
```

## Usage with Query Builder

You can paginate custom queries by passing on the query builder:

### Example

```typescript
const queryBuilder = repo
  .createQueryBuilder('cats')
  .leftJoinAndSelect('cats.owner', 'owner')
  .where('cats.owner = :ownerId', { ownerId })

const result = await paginate<CatEntity>(query, queryBuilder, config)
```

## Usage with Relations

Similar as with repositories, you can utilize `relations` as a simplified left-join form:

### Example

#### Endpoint

```url
http://localhost:3000/cats?filter.toys.name=$in:Mouse,String
```

#### Code

```typescript
const config: PaginateConfig<CatEntity> = {
  relations: ['toys'],
  sortableColumns: ['id', 'name', 'toys.name'],
  filterableColumns: {
    'toys.name': [FilterOperator.IN],
  },
}

const result = await paginate<CatEntity>(query, catRepo, config)
```