> ## Documentation Index
> Fetch the complete documentation index at: https://nestjs-query.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Hooks

> Hooks transform generated endpoint arguments before the query service is called. REST currently exposes , , and . A hook can be an inline function or an injectable class.

## Mutation hooks[​](#mutation-hooks "Direct link to Mutation hooks")

Decorate the create or update DTO when a value should be derived from the HTTP request rather than accepted from the client.

todo-item-input.dto.ts

```ts theme={null}
import { Request } from 'express'
import { BeforeCreateOne, CreateOneInputType, Field } from '@ptc-org/nestjs-query-rest'

type AuthenticatedRequest = Request & {
  user: { id: string }
}

@BeforeCreateOne((args: CreateOneInputType<TodoItemInputDTO>, request: AuthenticatedRequest) => ({
  input: {
    ...args.input,
    ownerId: request.user.id
  }
}))
export class TodoItemInputDTO {

  @Field()
  title!: string
  ownerId!: string
}
```

The function must return the complete wrapper (`{ input }` for create and `{ update }` for update), not only the inner DTO.

todo-item-update.dto.ts

```ts theme={null}
import { BeforeUpdateOne, UpdateOneInputType } from '@ptc-org/nestjs-query-rest'

@BeforeUpdateOne((args: UpdateOneInputType<TodoItemUpdateDTO>, request: AuthenticatedRequest) => ({
  update: {
    ...args.update,
    updatedById: request.user.id
  }
}))
export class TodoItemUpdateDTO {

  updatedById?: string
}
```

## Query hooks[​](#query-hooks "Direct link to Query hooks")

`BeforeQueryMany` receives the built core query and can add filters, sorting, or other query properties. It is also the place to interpret the optional search term enabled by `enableSearch`.

todo-item.dto.ts

```ts theme={null}
import { mergeFilter } from '@ptc-org/nestjs-query-core'
import { BeforeQueryMany, FilterableField, RestQuery } from '@ptc-org/nestjs-query-rest'

@BeforeQueryMany((query: RestQuery<TodoItemDTO>) => {
  if (!query.query) {
    return query
  }
  return {
    ...query,
    filter: mergeFilter(query.filter ?? {}, {
      title: { like: `%${query.query}%` }
    })
  }
})
export class TodoItemDTO {

  @FilterableField()
  title!: string
}
```

The same query hook runs for collection and CSV export requests.

## Injectable hooks[​](#injectable-hooks "Direct link to Injectable hooks")

Use a class when a hook needs injected services:

```ts theme={null}
import { Injectable } from '@nestjs/common'
import { BeforeCreateOneHook, CreateOneInputType } from '@ptc-org/nestjs-query-rest'

@Injectable()
export class SetOwnerHook implements BeforeCreateOneHook<TodoItemInputDTO, AuthenticatedRequest> {

  run(args: CreateOneInputType<TodoItemInputDTO>, request: AuthenticatedRequest) {
    return {
      input: { ...args.input, ownerId: request.user.id }
    }
  }
}

@BeforeCreateOne(SetOwnerHook)
export class TodoItemInputDTO {}
```

When DTOs are listed in `endpoints` or `dtos`, `NestjsQueryRestModule` discovers and registers their hook providers automatically.

[Edit this page](https://github.com/tripss/nestjs-query/edit/master/docs/rest/hooks)