# 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
- Select columns
- Filter using operators (`$eq`, `$not`, `$null`, `$in`, `$gt`, `$gte`, `$lt`, `$lte`, `$btw`, `$ilike`, `$sw`, `$contains`)
- Include relations and nested relations
- Virtual column support

## 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&select=id,name,color,age
```

#### 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'],
      nullSort: 'last',
      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: 'first' | 'last'
   * Default: 'first'
   * Description: (ONLY WORKS WITH POSTGRES) Define whether to put null values
   * at the beginning or end of the result set.
   */
  nullSort: 'last',

  /**
   * 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
   * Note: You must include the primary key in the selection.
   */
  select: ['name', 'color'],

  /**
   * Required: false
   * Type: number
   * Default: 100
   * Description: The maximum amount of entities to return per page.
   * Set it to 0, in conjunction with limit=0 on query param, to disable pagination.
   */
  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,

  /**
   * Required: false
   * Type: boolean
   * Default: false
   * Description: Generate relative paths in the resource links.
   */
  relativePath: true,

  /**
   * Required: false
   * Type: string
   * Description: Overrides the origin of absolute resource links if set.
   */
  origin: 'http://cats.example',

  /**
   * Required: false
   * Type: string
   * Description: Allow user to choose between limit/offset and take/skip.
   * Default: PaginationType.TAKE_AND_SKIP
   *
   * However, using limit/offset can return unexpected results.
   * For more information see:
   * [#477](https://github.com/ppetzold/nestjs-paginate/issues/477)
   * [#4742](https://github.com/typeorm/typeorm/issues/4742)
   * [#5670](https://github.com/typeorm/typeorm/issues/5670)
   */
  paginationType: PaginationType.LIMIT_AND_OFFSET,

  /**
   * Required: false
   * Type: boolean
   * Default: false
   * Description: Load eager relations using TypeORM's eager property.
   */
  loadEagerRelations: true
}
```

## 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)
```

**Note:** Embedded columns on relations have to be wrapped with brackets:

```typescript
const config: PaginateConfig<CatEntity> = {
  sortableColumns: ['id', 'name', 'toys.(size.height)', 'toys.(size.width)'],
  searchableColumns: ['name'],
  relations: ['toys'],
}
```

## Usage with Nested Relations

Similar as with relations, you can specify nested relations for sorting, filtering and searching:

### Example

#### Endpoint

```url
http://localhost:3000/cats?filter.home.pillows.color=pink
```

#### Code

```typescript
const config: PaginateConfig<CatEntity> = {
  relations: { home: { pillows: true } },
  sortableColumns: ['id', 'name', 'home.pillows.color'],
  searchableColumns: ['name', 'home.pillows.color'],
  filterableColumns: { 'home.pillows.color': [FilterOperator.EQ] },
}

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

## Usage with Eager Loading

Eager loading should work with TypeORM's eager property out of the box:

### Example

#### Code

```typescript
@Entity()
export class CatEntity {
  // ...

  @OneToMany(() => CatToyEntity, (catToy) => catToy.cat, {
    eager: true,
  })
  toys: CatToyEntity[]
}

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

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

## Single Filters

Filter operators must be whitelisted per column in `PaginateConfig`.

### Examples

`?filter.name=$eq:Milo` is equivalent with `?filter.name=Milo`

`?filter.age=$btw:4,6` where column `age` is between `4` and `6`

`?filter.id=$not:$in:2,5,7` where column `id` is **not** `2`, `5` or `7`

`?filter.summary=$not:$ilike:term` where column `summary` does **not** contain `term`

`?filter.summary=$sw:term` where column `summary` starts with `term`

`?filter.seenAt=$null` where column `seenAt` is `NULL`

`?filter.seenAt=$not:$null` where column `seenAt` is **not** `NULL`

`?filter.createdAt=$btw:2022-02-02,2022-02-10` where column `createdAt` is between the dates `2022-02-02` and `2022-02-10`

`?filter.roles=$contains:Moderator` where column `roles` is an array and contains the value "Moderator".

`?filter.roles=$contains:Moderator,Admin` where column `roles` is an array and contains the values "Moderator" and "Admin".

## Multi Filters

Multi filters are filters that can be applied to a single column with a comparator. As for single filters, multi filters must be whitelisted per column in `PaginateConfig`.

### Examples

`?filter.id=$gt:3&filter.id=$lt:5` where column `id` is greater than `3` **and** less than `5`

`?filter.id=$gt:3&filter.id=$or:$lt:5` where column `id` is greater than `3` **or** less than `5`

`?filter.id=$gt:3&filter.id=$and:$lt:5&filter.id=$or:$eq:7` where column `id` is greater than `3` **and** less than `5` **or** equal to `7`

**Note:** The `$and` comparators are not required. The above example is equivalent to:

`?filter.id=$gt:3&filter.id=$lt:5&filter.id=$or:$eq:7`

**Note:** The first comparator on the the first filter is ignored because the filters are grouped by the column name and chained with an `$and` to other filters.

`...&filter.id=5&filter.id=$or:7&filter.name=Milo&...`

is resolved to:

`WHERE ... AND (id = 5 OR id = 7) AND name = 'Milo' AND ...`

## Troubleshooting

The package does not report error reasons in the response bodies. They are instead
reported as `debug` level [logging](https://docs.nestjs.com/techniques/logger#logger).

Common errors include missing `sortableColumns` or `filterableColumns` (the latter only affects filtering).