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- 如果随意throw一个error，会被解析成500，但设置了statusCode和message，则会被正常返回
```
 const err =  new Error('test123');
    // @ts-ignore
    err.statusCode = 403;
```

- validate一个object，要么走zod，要么走class-validator+class-transform
```

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

@Injectable()
export class ValidationPipe implements PipeTransform<any> {
    async transform(value: any, { metatype }: ArgumentMetadata) {
        console.log('!!!!!', typeof value);
        console.log('!!!!!', typeof metatype);

if (!metatype || !this.toValidate(metatype)) {
            return value;
        }

// metatype是dto类， value是body里的值
        const object = plainToInstance(metatype, value);
        const errors = await validate(object);
        if (errors.length > 0) {
            throw new BadRequestException('Validation failed' + errors.toString());
        }
        return value;
    }

private toValidate(metatype: Function): boolean {
        const types: Function[] = [String, Boolean, Number, Array, Object];
        return !types.includes(metatype);
    }
}

```
上面这个ValidatorPipe其实没必要写，因为nest原生的就提供。另外，可以app.useGlobalPipe去设置，也可以在controller，方法，或者参数上去设置