Merge pull request nestjs#1348 from nestjs/feature/1267-validation-factory

feature(common) add validation error factory (ValidationPipe)

Author: kamilmysliwiec

packages/common/index.ts

@@ -40,6 +40,7 @@ export {
   Provider,
   RpcExceptionFilter,
   Type,
+  ValidationError,
   WebSocketAdapter,
   WsExceptionFilter,
 } from './interfaces';

packages/common/interfaces/external/validation-error.interface.ts

@@ -0,0 +1,28 @@
+/**
+ * Validation error description.
+ * @see https://github.com/typestack/class-validator
+ */
+export interface ValidationError {
+  /**
+   * Object that was validated.
+   */
+  target: Object;
+  /**
+   * Object's property that haven't pass validation.
+   */
+  property: string;
+  /**
+   * Value that haven't pass a validation.
+   */
+  value: any;
+  /**
+   * Constraints that failed validation with error messages.
+   */
+  constraints: {
+    [type: string]: string;
+  };
+  /**
+   * Contains all nested validation errors of the property.
+   */
+  children: ValidationError[];
+}

packages/common/interfaces/index.ts

@@ -4,6 +4,7 @@ export * from './controllers/controller.interface';
 export * from './exceptions/exception-filter.interface';
 export * from './exceptions/rpc-exception-filter.interface';
 export * from './exceptions/ws-exception-filter.interface';
+export * from './external/validation-error.interface';
 export * from './features/arguments-host.interface';
 export * from './features/can-activate.interface';
 export * from './features/custom-route-param-factory.interface';

packages/common/pipes/validation.pipe.ts

@@ -1,14 +1,19 @@
 import { Optional } from '../decorators';
-import { ArgumentMetadata, BadRequestException } from '../index';
+import { Injectable } from '../decorators/core/component.decorator';
+import {
+  ArgumentMetadata,
+  BadRequestException,
+  ValidationError,
+} from '../index';
 import { ValidatorOptions } from '../interfaces/external/validator-options.interface';
 import { PipeTransform } from '../interfaces/features/pipe-transform.interface';
 import { loadPackage } from '../utils/load-package.util';
 import { isNil } from '../utils/shared.utils';
-import { Injectable } from '../decorators/core/component.decorator';
 
 export interface ValidationPipeOptions extends ValidatorOptions {
   transform?: boolean;
   disableErrorMessages?: boolean;
+  exceptionFactory?: (errors: ValidationError[]) => any;
 }
 
 let classValidator: any = {};
@@ -19,13 +24,20 @@ export class ValidationPipe implements PipeTransform<any> {
   protected isTransformEnabled: boolean;
   protected isDetailedOutputDisabled?: boolean;
   protected validatorOptions: ValidatorOptions;
+  protected exceptionFactory: (errors: ValidationError[]) => any;
 
   constructor(@Optional() options?: ValidationPipeOptions) {
     options = options || {};
     const { transform, disableErrorMessages, ...validatorOptions } = options;
     this.isTransformEnabled = !!transform;
     this.validatorOptions = validatorOptions;
     this.isDetailedOutputDisabled = disableErrorMessages;
+    this.exceptionFactory =
+      options.exceptionFactory ||
+      (errors =>
+        new BadRequestException(
+          this.isDetailedOutputDisabled ? undefined : errors,
+        ));
 
     const loadPkg = pkg => loadPackage(pkg, 'ValidationPipe');
     classValidator = loadPkg('class-validator');
@@ -43,15 +55,13 @@ export class ValidationPipe implements PipeTransform<any> {
     );
     const errors = await classValidator.validate(entity, this.validatorOptions);
     if (errors.length > 0) {
-      throw new BadRequestException(
-        this.isDetailedOutputDisabled ? undefined : errors,
-      );
+      throw this.exceptionFactory(errors);
     }
     return this.isTransformEnabled
       ? entity
       : Object.keys(this.validatorOptions).length > 0
-        ? classTransformer.classToPlain(entity)
-        : value;
+      ? classTransformer.classToPlain(entity)
+      : value;
   }
 
   private toValidate(metadata: ArgumentMetadata): boolean {