Manual validation

Validate using methods

Inject the OpenAPIValidatorService using the OPENAPI_VALIDATOR token for custom validation logic in guards, filters, services, or middleware:

import { Injectable, Inject } from "@nestjs/common";
import { HttpArgumentsHost } from "@nestjs/common/interfaces";
import {
  OPENAPI_VALIDATOR,
  OpenAPIValidatorService,
} from "@nest-openapi/validator";

@Injectable()
export class MyService {
  constructor(
    @Inject(OPENAPI_VALIDATOR)
    private readonly validator: OpenAPIValidatorService
  ) {}

  validateData(httpContext: HttpArgumentsHost, responseBody) {
    // Validate requests manually
    const bodyOnlyErrors = this.validator.validateRequest(httpContext, {
      body: true,
      params: false,
      query: false,
    });

    // Validate responses manually
    const responseErrors = this.validator.validateResponse(
      httpContext,
      statusCode,
      responseBody
    );
  }
}

Error response validation

By default, the response validation interceptor only validates successful responses that flow through the normal pipeline. However, error responses (like NotFoundException, BadRequestException, etc.) bypass interceptors and go through exception filters.

To validate error responses, inject the validator service in your exception filter:

import {
  Catch,
  ExceptionFilter,
  ArgumentsHost,
  Injectable,
  Inject,
} from "@nestjs/common";
import {
  OPENAPI_VALIDATOR,
  OpenAPIValidatorService,
} from "@nest-openapi/validator";

@Catch()
@Injectable()
export class GlobalExceptionFilter implements ExceptionFilter {
  constructor(
    @Inject(OPENAPI_VALIDATOR)
    private readonly validator: OpenAPIValidatorService
  ) {}

  catch(exception: any, host: ArgumentsHost) {
    const ctx = host.switchToHttp();
    const response = ctx.getResponse();

    const status = exception.getStatus?.() || 500;
    const responseBody = {
      message: exception.message,
      statusCode: status,
      timestamp: new Date().toISOString(),
    };

    const validationErrors = this.validator.validateResponse(
      ctx,
      status,
      responseBody
    );

    if (validationErrors.length > 0) {
      console.warn("Error response validation failed:", validationErrors);
      // Handle validation errors as needed
    }

    response.status(status).json(responseBody);
  }
}

Then register your exception filter:

// app.module.ts
@Module({
  providers: [
    {
      provide: APP_FILTER,
      useClass: GlobalExceptionFilter,
    },
  ],
})
export class AppModule {}