Is there a way to declare a default value when using @ApiQuery with nestJS and swagger?

Question

EDIT: found a solution thanks to the comment suggesting to use a DTO. Answer detailed at the bottom.

The NestJS website has documentation to [declare default values][1] when using @ApiBody(), is there a way to do so with @ApiQuery()? (i.e. show in the documentation that the queries have default values)

for example, if I have pagination queries and want the default to be page 1 with 5 entries per page:

  @Get()
  @ApiQuery({name: 'page', default: 1, type: Number})
  @ApiQuery({name: 'limit', default: 5, type: Number})
  async getDocuments(
    @Query('page') page: Number = 1, 
    @Query('limit') limit: Number = 5
  ){
    return this.documentsService.getDocuments(page, limit);
  }

The above is what I would like to achieve. In reality, adding “default” key to ApiQuery throws an error. — Cris, May 07 '21 at 21:14
Just tried it out and it works (edited the original post to show my implementation), does it look correct? Thank you so much! — Cris, May 07 '21 at 22:07
FYI: you can (and usually should) post an answer to your own question rather than editing the answer into the question — Ryan M, May 07 '21 at 22:49

score 4 · Accepted Answer · answered May 08 '21 at 17:55

Using DTO as suggested in the comments:

//dto.ts
export class PageDTO {
  @ApiProperty({default: 1, required: false})
  page: Number
}
export class LimitDTO {
  @ApiProperty({default: 5, required: false})
  limit: Number
}
//documents.controller.ts
...
  @Get()
  @ApiQuery({name: 'page', default: 1, type: PageDTO})
  @ApiQuery({name: 'limit', default: 5, type: LimitDTO})
  async getDocuments(
    @Query('page') page = 1, 
    @Query('limit') limit = 5
  ){
    return this.documentsService.getDocuments(page, limit);
  }

The result: *made a typo, default here says 0 but it should be 1

Furthermore, a single DTO can be used for multiple query parameters. This is especially useful if the same params are being used by multiple functions:

//dto.ts
export class PaginationDTO {
  @ApiProperty({default: 1, required: false})
  page: Number
  @ApiProperty({default: 5, required: false})
  limit: Number
}

//documents.controller.ts
...
  @Get()
  @ApiQuery({type: PaginationDTO})
  async getDocuments(
    @Query('page') page = 1, 
    @Query('limit') limit = 5 
  ){
    return this.documentsService.getDocuments(page, limit);
  }

Also note the omission of type declarations on my working examples --this is because if the type is declared, swagger produces duplicate params

score 2 · Answer 2 · answered Aug 05 '21 at 08:54

  @Get()
  @ApiQuery({name: 'page', type: Number})
  @ApiQuery({name: 'limit', type: Number})
  async getDocuments(
    @Query('page', new DefaultValuePipe(1), ParseIntPipe) page: Number = 1, 
    @Query('limit', new DefaultValuePipe(5), ParseIntPipe) limit: Number = 5
  ){
    return this.documentsService.getDocuments(page, limit);
  }

Is there a way to declare a default value when using @ApiQuery with nestJS and swagger?

2 Answers2