Version: 4.0.0

Parameter Validation

We often need to perform type checking and parameter conversion operations when calling methods. Midway provides a simple capability to quickly check parameter types.

This module replaces the @midwayjs/validate component starting from v4.0.0.

The new version provides a more flexible validator extension mechanism, supports seamless switching between multiple validators (such as Joi, Zod, etc.), and provides better type support and performance optimization.

Related information:

Description
Can be used for standard projects	✅
Can be used for Serverless	✅
Can be used for integration	✅
Contains independent main framework	❌
Contains independent logs	❌

Background

The most commonly used place for parameter validation is the controller (Controller), and you can also use this capability in any Class.

We'll use the controller (Controller) as an example.

➜  my_midway_app tree
.
├── src
│   ├── controller
│   │   └── user.ts
│   ├── interface.ts
│   └── service
│       └── user.ts
├── test
├── package.json
└── tsconfig.json

In normal situations, we get all Post results from body and perform some validation.

// src/interface.ts
export interface User {
  id: number;
  firstName: string;
  lastName: string;
  age: number;
}

// src/controller/home.ts
import { Controller, Get, Provide } from '@midwayjs/core';

@Controller('/api/user')
export class HomeController {
  @Post('/')
  async updateUser(@Body() user: User) {
    if (!user.id || typeof user.id !== 'number') {
      throw new Error('id error');
    }

    if (user.age <= 30) {
      throw new Error('age not match');
    }
    // xxx
  }
}

If every method needs such validation, it would be very tedious.

For this situation, Midway provides the Validation component. Combined with @Validate and @Rule decorators, it is used to quickly define validation rules and help users reduce these repetitive codes.

The following general capabilities will be exemplified with joi.

Install Dependencies

You need to install the validation component and corresponding validators.

## Install validation component
$ npm i @midwayjs/validation@4 --save

## Choose one or more validators
$ npm i @midwayjs/validation-joi@4 --save

## Base library
$ npm i joi --save

Or add the following dependencies to package.json and reinstall.

{
  "dependencies": {
    "@midwayjs/validation": "^4.0.0",
    "@midwayjs/validation-joi": "^4.0.0",
    "joi": "^17.13.3",
    // ...
  },
  "devDependencies": {
    // ...
  }
}

Enable Component

Add the component in configuration.ts:

import { Configuration, App } from '@midwayjs/core';
import * as koa from '@midwayjs/koa';
import * as validation from '@midwayjs/validation';
import { join } from 'path';

@Configuration({
  imports: [
    koa,
    validation,
    // ... other components
  ],
  importConfigs: [join(__dirname, './config')],
})
export class MainConfiguration {
  @App()
  app: koa.Application;

  async onReady() {
    // ...
  }
}

Set the validator in the configuration file:

// src/config/config.default.ts
import joi from '@midwayjs/validation-joi';

export default {
  // ...
  validation: {
    // Configure validators
    validators: {
      joi,
    },
    // Set default validator
    defaultValidator: 'joi'
  }
}

Validation Rules

Through the @Rule decorator, you can pass validation rules.

import { Rule } from '@midwayjs/validation';
import * as Joi from 'joi';

export class UserDTO {
  @Rule(Joi.number().required())
  id: number;

  @Rule(Joi.string().required())
  firstName: string;

  @Rule(Joi.string().max(10))
  lastName: string;

  @Rule(Joi.number().max(60))
  age: number;
}

Validate Parameters

After defining the types, you can use them directly in business code, and the framework will automatically help you validate and convert DTOs.

// src/controller/home.ts
import { Controller, Get, Provide, Body } from '@midwayjs/core';
import { UserDTO } from './dto/user';

@Controller('/api/user')
export class HomeController {
  @Post('/')
  async updateUser(@Body() user: UserDTO) {
    // user.id
  }
}

All validation code is gone, making the business more pure. Of course, remember to replace the original user interface with a Class.

Once validation fails, the browser or console will report similar errors.

ValidationError: "id" is required

At the same time, since the type of id is defined, when getting a string, it will automatically convert id to a number.

async updateUser(@Body() user: UserDTO ) {
  // typeof user.id === 'number'
}

If you need to configure information separately at the method level, you can use the @Validate decorator, such as configuring error status separately.

// src/controller/home.ts
import { Controller, Get, Provide } from '@midwayjs/core';
import { Validate } from '@midwayjs/validation';
import { UserDTO } from './dto/user';

@Controller('/api/user')
export class HomeController {
  @Post('/')
  @Validate({
    errorStatus: 422,
  })
  async updateUser(@Body() user: UserDTO) {
    // user.id
  }
}

astuce

The @Validate decorator can pass multiple configuration items, such as errorStatus, locale, etc.

Configuration Item	Type	Description
errorStatus	number	HTTP status code returned when validation fails, effective in HTTP scenarios, default 422
locale	string	Default language for validation error text, default is `en_US`, will switch according to i18n component rules
throwValidateError	boolean	Whether to throw validation errors, default `true`, if set to `false`, returns validation results
defaultValidator	string	Set the default validator to use

Validation Results

The validation result is an object that contains validation status, validation errors, validation values and other information. Midway encapsulates the return values of different validators and unifies the format of return values.

The overall structure is as follows:

interface ValidateResult {
  /**
   * Whether validation is successful
   */
  status: boolean;
  /**
   * Validation error, if there are multiple errors, returns the first error
   */
  error?: any;
  /**
   * All validation errors
   */
  errors?: any[];
  /**
   * Validation error message, if there are multiple errors, returns the message of the first error
   */
  message?: string;
  /**
   * All validation error messages
   */
  messages?: string[];
  /**
   * Additional validation information
   */
  extra?: any;
}

astuce

Returns from different validators have been processed into the same structure.

General Scenario Validation

If the parameter is not a DTO, you can use the @Valid decorator for validation. The @Valid decorator can directly pass a validation rule.

Using Joi:

import { Controller, Get, Query } from '@midwayjs/core';
import { Valid } from '@midwayjs/validation';
import * as Joi from 'joi';

@Controller('/api/user')
export class HomeController {
  @Get('/')
  async getUser(@Valid(Joi.number().required()) @Query('id') id: number) {
    // ...
  }
}

Using Zod:

import { Controller, Get, Query } from '@midwayjs/core';
import { Valid } from '@midwayjs/validation';
import { z } from 'zod';

@Controller('/api/user')
export class HomeController {
  @Get('/')
  async getUser(@Valid(z.number().min(1)) @Query('id') id: number) {
    // ...
  }
}

In non-Web scenarios, where there are no Web decorators like @Body, you can also use the @Valid decorator for validation.

import { Valid } from '@midwayjs/validation';
import { Provide } from '@midwayjs/core';
import { UserDTO } from './dto/user';

@Provide()
export class UserService {
  async updateUser(@Valid() user: UserDTO) {
    // ...
  }
}

Validation Pipes

If your parameters are basic types, such as number, string, boolean, you can use the pipes provided by the component for validation.

All default Web parameter decorators can pass pipes in the second parameter.

For example:

import { ParseIntPipe } from '@midwayjs/validation';
import { Controller, Post, Body } from '@midwayjs/core';

@Controller('/api/user')
export class HomeController {
  @Post('/update_age')
  async updateAge(@Body('age', [ParseIntPipe]) age: number) {
    // ...
  }
}

The ParseIntPipe pipe can convert string and number data to numbers, so the age field obtained from request parameters will be validated and converted to number format through the pipe.

Available built-in pipes include:

ParseIntPipe
ParseFloatPipe
ParseBoolPipe
DefaultValuePipe

ParseIntPipe is used to convert parameters to integer numbers.

import { ParseIntPipe } from '@midwayjs/validation';

// ...
async update(@Body('age', [ParseIntPipe]) age: number) {
  return age;
}

update({ age: '12'} ); => 12
update({ age: '12.2'} ); => Error
update({ age: 'abc'} ); => Error

ParseFloatPipe is used to convert parameters to floating-point numbers.

import { ParseFloatPipe } from '@midwayjs/validation';

// ...
async update(@Body('size', [ParseFloatPipe]) size: number) {
  return size;
}

update({ size: '12.2'} ); => 12.2
update({ size: '12'} ); => 12

ParseBoolPipe is used to convert parameters to boolean values.

import { ParseBoolPipe } from '@midwayjs/validation';

// ...
async update(@Body('isMale', [ParseBoolPipe]) isMale: boolean) {
  return isMale;
}

update({ isMale: 'true'} ); => true
update({ isMale: '0'} ); => Error

DefaultValuePipe is used to set default values.

import { DefaultValuePipe } from '@midwayjs/validation';

// ...
async update(@Body('nickName', [new DefaultValuePipe('anonymous')]) nickName: string) {
  return nickName;
}

update({ nickName: undefined} ); => 'anonymous'

Custom Validation Pipes

If the default pipes don't meet your needs, you can quickly implement a custom validation pipe by inheritance. The component already provides a ParsePipe class for quick writing.

import { Pipe } from '@midwayjs/core';
import { ParsePipe, RuleType } from '@midwayjs/validation';

@Pipe()
export class ParseCustomDataPipe extends ParsePipe {
  getSchema() {
    // ...
  }
}

The getSchema method is used to return a validation rule.

For example, the code for ParseIntPipe is as follows. When the pipe is executed, it will automatically get this schema for validation and return the value after successful validation.

We still use joi as an example.

import { Pipe } from '@midwayjs/core';
import { ParsePipe, RuleType } from '@midwayjs/validation';
import * as Joi from 'joi';

@Pipe()
export class ParseIntPipe extends ParsePipe {
  getSchema() {
    return Joi.number().integer().required();
  }
}

Validation Rules

astuce

The use of RuleType has been removed in the new version, you can directly use the corresponding validator syntax.
The @Rule decorator can pass rules from different types of validators.
In the @Rule decorator, when using the getSchema method, you need to use arrow functions.

Common joi Validation Syntax

import * as Joi from 'joi';

Joi.number().required(); // number, required
Joi.string().empty(''); // string, not required
Joi.number().max(10).min(1); // number, max and min values
Joi.number().greater(10).less(50); // number, greater than 10, less than 50

Joi.string().max(10).min(5); // string, max length 10, min length 5
Joi.string().length(20); // string, length 20
Joi.string().pattern(/^[abc]+$/); // string, match regex format

Joi.object().length(5); // object, key count equals 5

Joi.array().items(Joi.string()); // array, each element is a string
Joi.array().max(10); // array, max length 10
Joi.array().min(10); // array, min length 10
Joi.array().length(10); // array, length 10

Joi.string().allow(''); // non-required field passes empty string

export enum DeviceType {
  iOS = 'ios',
  Android = 'android',
}
Joi.string().valid(...Object.values(DeviceType)) // validate based on enum values

Cascading Validation

Midway supports properties in each validation Class that are still objects.

We add a property school to UserDTO and assign it a SchoolDTO type.

import { Rule, getSchema } from '@midwayjs/validation';
import * as Joi from 'joi';

export class SchoolDTO {
  @Rule(Joi.string().required())
  name: string;
  @Rule(Joi.string())
  address: string;
}

export class UserDTO {
  @Rule(Joi.number().required())
  id: number;

  @Rule(Joi.string().required())
  firstName: string;

  @Rule(Joi.string().max(10))
  lastName: string;

  // Complex object
  // The validator is not registered when this executes, so arrow functions are needed
  @Rule(() => getSchema(SchoolDTO).required())
  school: SchoolDTO;

  // Object array
  @Rule(() => Joi.array().items(getSchema(SchoolDTO)).required())
  schoolList: SchoolDTO[];
}

At this time, the parameter of the @Rule decorator can be the type itself that needs to be validated.

Inheritance Validation

Midway supports validation inheritance, satisfying developers' needs to extract common object properties when doing parameter validation.

For example, our CommonUserDTO below extracts some common properties of the interface, and then UserDTO serves as specific parameters needed for special interfaces.

import { Rule } from '@midwayjs/validation';

export class CommonUserDTO {
  @Rule(Joi.string().required())
  token: string;
  @Rule(Joi.string())
  workId: string;
}

export class UserDTO extends CommonUserDTO {
  @Rule(Joi.string().required())
  name: string;
}

The old version needed to be added to the subclass, but the new version doesn't need it anymore~

info

If property names are the same, the current property's rules are used for validation and won't merge with the parent class.

Multi-type Validation

Starting from v3.4.5, Midway supports validation of different types for a property.

For example, a certain type can be either a common type or a complex type.

import { Rule, getSchema } from '@midwayjs/validation';
import * as Joi from 'joi';

export class SchoolDTO {
  @Rule(Joi.string().required())
  name: string;
  @Rule(Joi.string())
  address: string;
}

export class UserDTO {
  @Rule(Joi.string().required())
  name: string;

  @Rule(() => Joi.alternatives([Joi.string(), getSchema(SchoolDTO)]).required())
  school: string | SchoolDTO;
}

We can use the getSchema method to get the current schema from a DTO for complex logic processing.

Creating New DTOs from Existing DTOs

Sometimes, we want to get some properties from a DTO and turn them into a new DTO class.

Midway provides PickDto and OmitDto methods to create new DTOs based on existing DTO types.

PickDto is used to get some properties from existing DTOs to create new DTOs, while OmitDto is used to exclude certain properties, for example:

// src/dto/user.ts
import { Rule, PickDto } from '@midwayjs/validation';

export class UserDTO {
  @Rule(Joi.number().required())
  id: number;

  @Rule(Joi.string().required())
  firstName: string;

  @Rule(Joi.string().max(10))
  lastName: string;

  @Rule(Joi.number().max(60))
  age: number;
}

// Inherit a new DTO
export class SimpleUserDTO extends PickDto(UserDTO, ['firstName', 'lastName']) {}

// const simpleUser = new SimpleUserDTO();
// Only contains firstName and lastName properties
// simpleUser.firstName = xxx

export class NewUserDTO extends OmitDto(UserDTO, ['age']) {}

// const newUser = new NewUserDTO();
// newUser.age definition and property don't exist

// Usage
async login(@Body() user: NewUserDTO) {
  // ...
}

Internationalization

By default, en_US and zh_CN translation texts for validation are provided, so when requests fail, the language specified by the current browser access will be returned.

Specify Language Through Decorator

By default, it follows the defaultLocale of the i18n component and the browser access language to return messages. However, we can specify the current translation language in the decorator, for example:

@Controller('/user')
export class UserController {
  @Post('/')
  @Validate({
    locale: 'en_US',
  })
  async getUser(@Body() bodyData: UserDTO) {
    // ...
  }
}

Specify Language Through Parameters

In addition to decorator specification, we can also use the standard i18n method of specifying language through parameters.

For example, Query parameters.

Get /user/get_user?locale=zh_CN

For more parameter usage, please refer to the i18n component.

Translation for Other Languages

By default, Midway provides en_US and zh_CN validation translation texts. If additional translations are needed, they can be configured in i18n.

For example:

// src/config/config.default.ts
export default {
  // ...
  i18n: {
    // Add translation
    zh_TW: {
      validate: require('../../locales/zh_TW.json'),
    },
  },
};

Custom Error Text

If you only want to define the error message for a certain rule in a DTO, you can simply specify it.

export class UserDTO {
  @Rule(RuleType.number().required().error(new Error('my custom message')))
  id: number;
}

Default Configuration

In src/config/config.default.ts, we can configure the validation component.

Configuration Item	Type	Description
errorStatus	number	HTTP status code returned when validation fails, effective in HTTP scenarios, default 422
locale	string	Default language for validation error text, default is `en_US`, will switch according to i18n component rules
validators	Record<string, Function>	Configure validators to use
defaultValidator	string	Set the default validator to use, if not set, uses the first validator the user `require`d

Advanced

Independent Validation Service

The component provides a singleton ValidationService validation service class at the bottom level. If necessary, it can be used in middleware or independent services.

import { ValidationService } from '@midwayjs/validation';

export class UserService {
  @Inject()
  validateService: ValidationService;

  async invoke() {
    // ...
    const result = this.validateService.validate(UserDTO, {
      name: 'harry',
      nickName: 'harry',
    }, {
      throwValidateError: false,
    });

    if (result.status) {
      // Success
    } else {
      // Failure
    }
  }
}

Using `zod` Validator

Midway supports both Zod v3 and Zod v4 versions, you can choose according to project requirements:

@midwayjs/validation-zod - Supports Zod v3 (3.x)
@midwayjs/validation-zod4 - Supports Zod v4 (4.x)

Zod v3
Zod v4

If you choose to use the Zod v3 validator, you need to first install the related dependency packages:

$ npm i @midwayjs/validation@4 @midwayjs/validation-zod@4 zod@3 --save

Set the validator in the configuration file:

// src/config/config.default.ts
import zod from '@midwayjs/validation-zod';

export default {
  // ...
  validation: {
    // Configure validators
    validators: {
      'zod': zod,
    },
    // Set default validator
    defaultValidator: 'zod'
  }
}

Then you can use Zod validation rules:

import { Rule } from '@midwayjs/validation';
import { z } from 'zod';

export class UserDTO {
  @Rule(z.number().min(1))
  id: number;

  @Rule(z.string().min(1))
  firstName: string;

  @Rule(z.string().max(10))
  lastName: string;

  @Rule(z.number().max(60))
  age: number;
}

The Zod validator uses translations provided by zod-i18n-map, supporting more languages, including:

Simplified Chinese (zh-CN)
Traditional Chinese (zh-TW)
English (en)
Japanese (ja)
Korean (ko)
Russian (ru)

And many other languages.

If needed, you can refer to the zod-i18n-map documentation to add support for more languages.

// src/config/config.default.ts
export default {
  // ...
  i18n: {
    // Configure validators
    localeTable: {
      zh_TW: {
        zod: require('zod-i18n-map/locales/zh-TW/zod.json'),
      },
    },
  }
}

If you choose to use the Zod v4 validator, you need to first install the related dependency packages:

$ npm i @midwayjs/validation@4 @midwayjs/validation-zod4@4 zod@4 --save

Set the validator in the configuration file:

// src/config/config.default.ts
import zod from '@midwayjs/validation-zod4';

export default {
  // ...
  validation: {
    // Configure validators
    validators: {
      'zod': zod,
    },
    // Set default validator
    defaultValidator: 'zod'
  }
}

You can use Zod validation rules directly:

import { Rule } from '@midwayjs/validation';
import { z } from 'zod';

export class UserDTO {
  @Rule(z.number().min(1))
  id: number;

  @Rule(z.string().min(1))
  firstName: string;

  @Rule(z.string().max(10))
  lastName: string;

  @Rule(z.number().max(60))
  age: number;
}

The Zod v4 validator uses translations provided by @semihbou/zod-i18n-map and supports more languages, including:

Simplified Chinese (zh-CN)
Traditional Chinese (zh-TW)
English (en)
Japanese (ja)
Korean (ko)
Russian (ru)

and many other languages.

If needed, you can refer to the documentation of https://github.com/VC-Semih/zod-i18n to add support for more languages.

// src/config/config.default.ts
export default {
  // ...
  i18n: {
    localeTable: {
      zh_TW: {
        zod: require('@semihbou/zod-i18n-map/locales/zh-TW/zod.json'),
      },
    },
  }
}

Using `class-validator` Validator

You need to first install class-validator and related dependency packages:

$ npm i @midwayjs/validation@4 @midwayjs/validation-class-validator@4 class-validator class-transformer --save

Set the validator in the configuration file:

// src/config/config.default.ts
import classValidator from '@midwayjs/validation-class-validator';

export default {
  // ...
  validation: {
    validators: {
      'class-validator': classValidator,
    },
    defaultValidator: 'class-validator'
  }
}

Then you can use class-validator validation rules:

import { Rule } from '@midwayjs/validation';
import { IsString, IsNumber } from 'class-validator';

export class UserDTO {
  @Rule(IsString())
  name: string;

  @Rule(IsNumber())
  age: number;
}

By default, for class-validator validation rules, Midway provides zh_CN and en_US translation texts.

If you need support for more languages, you can refer to the translation texts provided by class-validator-multi-lang.

For example, if we want to support Russian (ru) translation, we can copy the corresponding translation file and place it in the /locales/ru.json file. The configuration is as follows.

// src/config/config.default.ts
export default {
  // ...
  i18n: {
    // Configure validators
    localeTable: {
      ru_RU: {
        classValidator: require('../../locales/ru.json'),
      },
    },
  }
}

Mixed Validators

You can configure multiple validators in the same project.

// src/config/config.default.ts
import joi from '@midwayjs/validation-joi';
import zod from '@midwayjs/validation-zod';

export default {
  // ...
  validation: {
    // Configure validators
    validators: {
      'joi': joi,
      'zod': zod,
    },
    // Set default validator
    defaultValidator: 'joi'
  }
}

The @Rule decorator parameters can use different validation rules.

import { Rule } from '@midwayjs/validation';
import * as Joi from 'joi';
import { z } from 'zod';

export class UserDTO {
  @Rule(Joi.number().required())
  id: number;
  
  @Rule(Joi.string().required())
  name: string;
}

export class AnotherUserDTO {
  @Rule(z.number())
  id: number;
  
  @Rule(z.string().min(1))
  name: string;
}

astuce

You cannot use different validators in the same class.

You can manually select which validator to use through defaultValidator.

@Controller('/user')
export class UserController {
  @Post('/')
  @Validate({
    defaultValidator: 'zod',
  })
  async getUser(@Body() bodyData: AnotherUserDTO) {
    // ...
  }
}

It can also be used in ValidationService.

import { ValidationService } from '@midwayjs/validation';

export class UserService {
  @Inject()
  validateService: ValidationService;

  async invoke() {
    // ...
    const result = this.validateService.validate(UserDTO, {
      name: 'harry',
      nickName: 'harry',
    }, {
      defaultValidator: 'zod'
    });
  }
}

Custom Validators

In addition to using the built-in Joi and Zod validators, you can also implement your own validators. Validators need to implement the IValidationService interface:

import { IMidwayContainer } from '@midwayjs/core';
import { IValidationService, ValidateResult, ValidationExtendOptions } from '@midwayjs/validation';

class CustomValidator implements IValidationService<any> {
  // Initialize validator
  async init(container: IMidwayContainer): Promise<void> {
    // Perform initialization operations here
  }

  // Validate using schema
  validateWithSchema(
    schema: any,
    value: any,
    options: ValidationExtendOptions,
    validatorOptions: any
  ): ValidateResult {
    const res = {} as ValidateResult;
    try {
      // Implement your validation logic
      res.status = true;
      res.value = value;  // You can transform values here
    } catch (error) {
      res.status = false;
      res.error = error;
      res.message = error.message;
    }
    return res;
  }

  // Get schema
  getSchema(ClzType: any): any {
    // Implement logic to get schema
  }

  // Get basic type schemas
  getIntSchema(): any {
    // Return integer type schema
  }

  getBoolSchema(): any {
    // Return boolean type schema
  }

  getFloatSchema(): any {
    // Return float type schema
  }

  getStringSchema(): any {
    // Return string type schema
  }
}

// Export validator factory function
export default async (container: IMidwayContainer) => {
  return new CustomValidator();
};

Then use your custom validator in the configuration:

// src/config/config.default.ts
import customValidator from './custom.validator';

export default {
  validation: {
    validators: {
      custom: customValidator,  // Register custom validator
    },
    defaultValidator: 'custom'  // Set as default validator
  }
};

FAQ

1. Allow Undefined Fields in Joi

For the Joi validator, you can allow undefined fields through the following configuration:

// src/config/config.default.ts
export default {
  // ...
  joi: {
    allowUnknown: true,
  }
};

2. Handle Validation Errors

As mentioned above, Midway will throw a MidwayValidationError when validation fails, which we can handle in error filters.

// src/filter/validate.filter
import { Catch } from '@midwayjs/core';
import { MidwayValidationError } from '@midwayjs/validation';
import { Context } from '@midwayjs/koa';

@Catch(MidwayValidationError)
export class ValidateErrorFilter {
  async catch(err: MidwayValidationError, ctx: Context) {
    return {
      status: 422,
      message: 'Validation parameter error: ' + err.message,
    };
  }
}

3. Internationalization Not Working

Please use a browser, not Postman directly for testing.

Background​

Install Dependencies​

Enable Component​

Validation Rules​

Validate Parameters​

Validation Results​

General Scenario Validation​

Validation Pipes​

Custom Validation Pipes​

Validation Rules​

Common joi Validation Syntax​

Cascading Validation​

Inheritance Validation​

Multi-type Validation​

Creating New DTOs from Existing DTOs​

Internationalization​

Specify Language Through Decorator​

Specify Language Through Parameters​

Translation for Other Languages​

Custom Error Text​

Default Configuration​

Advanced​

Independent Validation Service​

Using zod Validator​

Using class-validator Validator​

Mixed Validators​

Custom Validators​

FAQ​

1. Allow Undefined Fields in Joi​

2. Handle Validation Errors​

3. Internationalization Not Working​

Background

Install Dependencies

Enable Component

Validation Rules

Validate Parameters

Validation Results

General Scenario Validation

Validation Pipes

Custom Validation Pipes

Validation Rules

Common joi Validation Syntax

Cascading Validation

Inheritance Validation

Multi-type Validation

Creating New DTOs from Existing DTOs

Internationalization

Specify Language Through Decorator

Specify Language Through Parameters

Translation for Other Languages

Custom Error Text

Default Configuration

Advanced

Independent Validation Service

Using `zod` Validator

Using `class-validator` Validator

Mixed Validators

Custom Validators

FAQ

1. Allow Undefined Fields in Joi

2. Handle Validation Errors

3. Internationalization Not Working