Using API model property with an array of types does not display correctly

I’m submitting a…

[ ] Regression 
[x] Bug report
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

Using API model property with an array of types does not display correctly

Expected behavior

An array of the object with the properties listed

Minimal reproduction of the problem with instructions

  @TreeChildren()
  @ApiModelProperty({
    description: 'Array of Child Conversations.',
    isArray: true,
    type: [Conversation],
  })
  @Field(/* istanbul ignore next */ _ => [Conversation])
  public children?: Conversation[];

What is the motivation / use case for changing the behavior?

Environment

Nest version: 7.1.5

 
For Tooling issues:
- Node version: 12.13.0
- Platform:  Mac

Others:

[iambpn]

For anyone who is trying to generate schema of array property in dto, here is the solution.

@ApiProperty({
  isArray: true
  type: AnotherClass
})
arr: AnotherClass[];

This will automatically generate AnotherClass Schema.

[marcinjahn]

I can’t get it to work, even with @iambpn’s suggested solution. Here’s my endpoint:

  @Get('cats')
  async cats(@Query() request: CatInput): Promise<CatDto> {
    return new Promise<CatDto>(() => {
        return {color: 'black', name: 'Abc'};
      }
    )
  }

I’d like CatInput to be properly rendered in Swagger It contains an array of objects called infos:

export class Info {
    public name: string;
    public color: string;
}

export class CatInput {
    public infos: Info[]
}

I’m using the nest swagger plugin. Here’re some of the options I tried:

1. No decorators added

export class Info {
    public name: string;
    public color: string;
}

export class CatInput {
    public infos: Info[]
}

Swagger UI does not allows me to input multiple infos. Even the single one I provide is sent wrong, missing the name of the infos field.

1. Added ApiProperty decorator as suggested by @iambpn

export class Info {
    public name: string;
    public color: string;
}

export class CatInput {
    @ApiProperty({isArray: true, type: Info})
    public infos: Info[]
}

I get exactly the same result as before. I cannot provide multiple infos.

1. Different form of ApiProperty

export class Info {
    public name: string;
    public color: string;
}

export class CatInput {
    @ApiProperty({isArray: true, type: [Info]})
    public infos: Info[]
}

Starts to look good. However, when I try to add an item:

Something is clearly wrong there, the swagger JSON is:

"parameters": [
          {
            "name": "infos",
            "required": true,
            "in": "query",
            "schema": {
              "type": "array",
              "items": {
                "type": "array",
                "items": {
                  "type": "a"
                }
              }
            }
          }
        ],

The specification is definitely wrong. Where does it take the type: "a" from?

---

Am I missing something? @kamilmysliwiec, let me know if I should create a new issue for this, this one seemed very similar to mine.