NestJS使用IntersectionType组合DTO后验证与Swagger文档失效问题

承接此前的问题，我尝试确保DTO组合后验证规则仍能生效，但使用@nestjs/swagger的IntersectionType组合DTO后出现以下问题：

1. 单个DTO验证正常 #

定义了AdminCodeDTO（要求AdminCode为1-999的必填数字）和DescriptionDTO（要求Description为3-20位的必填字符串），各自的单元测试均能返回预期的验证错误。

AdminCodeDTO 代码 #

import { IsNumber, Min, Max, IsDefined } from '@nestjs/class-validator';
import { ApiProperty, ApiResponseProperty } from '@nestjs/swagger';

export class AdminCodeDTO {
    @ApiProperty({
        description: 'Sweda Administration Code used for time tracking that is not part of a mantis.',
    })
    @ApiResponseProperty({ example: 5 })
    @IsDefined() @IsNumber() @Min(1) @Max(999) public AdminCode: number;

    constructor(AdminCode?: number) {
        this.AdminCode = AdminCode;
    }
}

DescriptionDTO 代码 #

import { IsDefined, IsString, MaxLength, MinLength } from '@nestjs/class-validator';
import { ApiProperty, ApiResponseProperty } from '@nestjs/swagger';

export class DescriptionDTO {
    @ApiProperty({
        description: '',
        minLength: 3,
        maxLength: 20
    })
    @ApiResponseProperty({ example: 'Sick Day' })
    @IsDefined() @IsString() @MaxLength(20) @MinLength(3) public Description: string;

    constructor(Description?: string) {
        this.Description = Description;
    }
}

2. 组合DTO验证失效 #

使用IntersectionType组合上述两个DTO得到AdmininstrationCodesDTO，虽能正确定义字段，但单元测试中验证规则不生效，空构造实例的验证错误数量不符合预期。

组合DTO代码 #

import { IsDefined, IsString, MaxLength, MinLength } from '@nestjs/class-validator';
import { ApiProperty, ApiResponseProperty, IntersectionType} from '@nestjs/swagger';
import { AdminCodeDTO } from './admin-code-dto';

export class AdmininstrationCodesDTO extends IntersectionType(
    AdminCodeDTO,
    DescriptionDTO
)
{
    constructor(AdminCode?: number, Description?: string) {
        this.AdminCode = AdminCode;
        this.Description = Description;
    }
}

测试代码 #

import { AdmininstrationCodesDTO } from './admininstration-codes-dto';

describe('AdmininstrationCodesDTO', () => {
    let TestDTO: AdmininstrationCodesDTO;
    beforeEach( () => {
        TestDTO = new AdmininstrationCodesDTO(77, 'Test Admin Code');
    })

    it('should be defined', () => {
        expect(TestDTO).toBeDefined();
    });

    it('should be defined when launched without parameters', () => {
        expect(new AdmininstrationCodesDTO()).toBeDefined();
    })

    it.each([
        ['AdminCode', 77],
        ['Description', 'Test Admin Code'],
    ])('should have the proper field {%s} set to be %d', (FieldName, Expected) => {
        expect(FieldName in TestDTO).toBe(true);
        expect(TestDTO[FieldName]).toBe(Expected);
    });

    // 此测试失败，验证规则未生效
    it('should generate the DTO errors', async () => {
        const TestDTO: AdmininstrationCodesDTO = new AdmininstrationCodesDTO();
        const Errors: Array<ValidationError> = await validate(TestDTO);
        expect(Errors.length).toBe(8);
    });
        
});

3. Swagger文档异常 #

组合DTO的请求架构无法在Swagger UI中显示字段，而直接定义字段的DTO可正常显示（项目为NX monorepo，已启用CLI功能）。

内容的提问来源于stack exchange，提问作者Steven Scott