import { ArgumentMetadata, BadRequestException, Injectable, PipeTransform } from '@nestjs/common'
import { plainToInstance } from 'class-transformer'
import { validate } from 'class-validator'
import { query } from 'express'

@Injectable()
export class ValidatePipe implements PipeTransform {
  async transform(value: any, metadata: ArgumentMetadata) {
    const { metatype } = metadata
    //前台提交的表单数据没有类型，使用 plainToClass 转为有类型的对象用于验证
    const object = plainToInstance(metatype, value)
    //根据 DTO 中的装饰器进行验证
    const errors = await validate(object)
    if (errors.length) {
      let res = errors.map((value) => {
        return {
          name: value?.property,
          msg: Object.values(value.constraints),
        }
      })
      throw new BadRequestException(res)
    }
    return value
  }
}