class-validator
Advanced tools
Class-based validation with Typescript / ES6 / ES5 using decorators or validation schemas. Supports both node.js and browser
The class-validator package is a TypeScript and JavaScript library that allows for validation of classes and objects using decorators and non-decorator based validation. It is commonly used to ensure data integrity before persistence or processing and is particularly useful when working with class-based models.
Declarative Validation Decorators
Allows the use of decorators to declare validation rules directly in the class model. For example, ensuring a property is not empty, is an integer, or is a valid email address.
{"@IsNotEmpty()": "public name: string;", "@IsInt()": "public age: number;", "@IsEmail()": "public email: string;"}Custom Validation Classes
Enables the creation of custom validation classes that implement the ValidatorConstraintInterface. This allows for complex and custom validation logic that can be reused across different class properties.
{"@ValidatorConstraint({ async: false })": "class IsLongerThanConstraint implements ValidatorConstraintInterface { validate(text: string, args: ValidationArguments) { return text.length > args.constraints[0]; } defaultMessage(args: ValidationArguments) { return 'Text is too short. Should be longer than ' + args.constraints[0] + ' characters'; } }", "@ValidatorConstraint()": "@IsLongerThan(10, { message: 'Text must be longer than 10 characters' }) public text: string;"}Validation of Nested Objects
Supports validation of nested objects using the ValidateNested decorator, ensuring that the properties of the nested objects also adhere to their respective validation rules.
{"@ValidateNested()": "@Type(() => SubClass) public nested: SubClass;"}Asynchronous Validation
Provides asynchronous validation functions like validateOrReject, which can handle async validators and return a promise that either resolves if the object is valid or rejects with the validation errors.
{"@IsEmail({}, { message: 'Invalid email' })": "public email: string;", "validateOrReject(someObject)": ".catch(errors => { console.log('Promise rejected (validation failed). Errors: ', errors); });"}Manual Validation
Allows for manual validation of objects without using decorators by calling the validate function, which returns a promise containing any validation errors.
{"validate(someObject)": ".then(errors => { if (errors.length > 0) { console.log('Validation failed: ', errors); } else { console.log('Validation succeed'); } });"}Joi is a powerful schema description language and data validator for JavaScript. Unlike class-validator, Joi does not use decorators and is schema-based. It is often used for object schema validation and can be used on both client and server sides.
Yup is a JavaScript schema builder for value parsing and validation. It defines a schema with a more fluent/chainable API and is less verbose than class-validator. It is often used in the context of form validation, especially with form libraries like Formik.
Ajv is a JSON schema validator. It validates data against JSON Schema (draft 6, draft 7, and draft 2019-09). It is known for its performance and is used for validating JSON data structures, unlike class-validator which is more focused on class and object validation.
Express-validator is a set of express.js middlewares that wraps validator.js, a library that provides validator and sanitizer functions. It is specifically designed for Express applications and allows for middleware-based validation, which is different from the decorator-based approach of class-validator.
Allows use of decorator and non-decorator based validation. Internally uses validator.js to perform validation. Class-validator works on both browser and node.js platforms.
Install module:
npm install class-validator --save
ES6 features are used, if you are using old versions of node (or browser) you may want to install es6-shim too:
npm install es6-shim --save
and use it somewhere in the global place of your app:
require("es6-shim") (or import "es6-shim";) in your app's entry point (for example in app.ts)<script src="node_modules/es6-shim/es6-shim.js"> in your index.htmlThis step is only required if you are using old versions of node/browser.
If you are using class-validator with system.js in browser then use following configuration:
System.config({
map: {
'class-validator': 'vendor/class-validator',
'validator': 'vendor/validator'
},
packages: {
'class-validator': { 'defaultExtension': 'js', 'main': 'index.js' },
'validator': { 'defaultExtension': 'js', 'main': 'validator.js' },
}
};
Create your class and put some validation decorators on the properties you want to validate:
import {validate, Contains, IsInt, Length, IsEmail, IsFQDN, IsDate, Min, Max} from "class-validator";
export class Post {
@Length(10, 20)
title: string;
@Contains("hello")
text: string;
@IsInt()
@Min(0)
@Max(10)
rating: number;
@IsEmail()
email: string;
@IsFQDN()
site: string;
@IsDate()
createDate: Date;
}
let post = new Post();
post.title = "Hello"; // should not pass
post.text = "this is a great post about hell world"; // should not pass
post.rating = 11; // should not pass
post.email = "google.com"; // should not pass
post.site = "googlecom"; // should not pass
validate(post).then(errors => { // errors is an array of validation errors
if (errors.length > 0) {
console.log("validation failed. errors: ", errors);
} else {
console.log("validation succeed");
}
});
validate method returns you an array of ValidationError objects. Each ValidationError is:
{
target: Object; // Object that was validated.
property: string; // Object's property that haven't pass validation.
value: any; // Value that haven't pass a validation.
constraints?: { // Constraints that failed validation with error messages.
[type: string]: string;
};
children?: ValidationError[]; // Contains all nested validation errors of the property
}
In our case, when we validated a Post object, we have such array of ValidationErrors:
[{
target: /* post object */,
property: "title",
value: "Hello",
constraints: {
length: "$property must be shorter than 10 characters"
}
}, {
target: /* post object */,
property: "text",
value: "this is a great post about hell world",
constraints: {
contains: "text must contain a hello string"
}
},
// and other errors
]
If you don't want a target to be exposed in validation errors, there is a special option when you use validator:
validator.validate(post, { error: { target: false } });
This is especially useful when you send errors back over http, and you most probably don't want to expose the whole target object.
You can specify validation message in the decorator options and that message will be returned in ValidationError
returned by validate method in the case that validation for this field fails.
import {MinLength, MaxLength} from "class-validator";
export class Post {
@MinLength(10, {
message: "Title is too short"
})
@MaxLength(50, {
message: "Title is too long"
})
title: string;
}
There are few special tokens you can use in your messages:
$value - the value that is being validated$property - name of the object's property being validated$target - name of the object's class being validated$constraint1, $constraint2, ... $constraintN - constraints defined by specific validation typeExample of usage:
import {MinLength, MaxLength} from "class-validator";
export class Post {
@MinLength(10, { // here, $constraint1 will be replaced with "10", and $value with actual supplied value
message: "Title is too short. Minimal length is $constraint1 characters, but actual is $value"
})
@MaxLength(50, { // here, $constraint1 will be replaced with "50", and $value with actual supplied value
message: "Title is too long. Maximal length is $constraint1 characters, but actual is $value"
})
title: string;
}
Also you can provide a function, that returns a message. This way allows to create more granular messages:
import {MinLength, MaxLength, ValidationArguments} from "class-validator";
export class Post {
@MinLength(10, {
message: (args: ValidationArguments) => {
if (args.value.length === 1) {
return "Too short, minimum length is 1 character";
} else {
return "Too short, minimum length is " + args.constraints[0] + " characters";
}
}
})
title: string;
}
Message function accepts ValidationArguments which contains following information:
value - the value that is being validatedconstraints - array of constraints defined by specific validation typetargetName - name of the object's class being validatedobject - object that is being validatedproperty - name of the object's property being validatedIf your field is an array and you want to perform validation of each item in the array you must specify a
special each: true decorator option:
import {MinLength, MaxLength} from "class-validator";
export class Post {
@MaxLength(20, {
each: true
})
tags: string[];
}
This will validate each item in post.tags array.
If your object contains nested objects and you want the validator to perform their validation too, then you need to
use the @ValidateNested() decorator:
import {ValidateNested} from "class-validator";
export class Post {
@ValidateNested()
user: User;
}
When you define a subclass which extends from another one, the subclass will automatically inherit the parent's decorators.
import {validate} from "class-validator";
class BaseContent {
@IsEmail()
email: string;
}
class Post extends BaseContent {
@MinLength(10)
@MaxLength(20)
title: string;
@Contains("hello")
text: string;
}
let post = new Post();
post.email = "invalid email"; // inherited property
post.title = "not valid";
post.text = "helo";
validate(post).then(errors => {
// ...
}); // it will return errors for email, title and text properties
The conditional validation decorator (@ValidateIf) can be used to ignore the validators on a property when the provided condition function returns false. The condition function takes the object being validated and must return a boolean.
import {ValidateIf, IsNotEmpty} from "class-validator";
export class Post {
otherProperty:string;
@ValidateIf(o => o.otherProperty === "value")
@IsNotEmpty()
example:string;
}
In the example above, the validation rules applied to example won't be run unless the object's otherProperty is "value".
Note that when the condition is false all validation decorators are ignored, including isDefined.
Sometimes you may want to skip validation of the properties that does not exist in the validating object. This is
usually desirable when you want to update some parts of the object, and want to validate only updated parts,
but skip everything else, e.g. skip missing properties.
In such situations you will need to pass a special flag to validate method:
import {validate} from "class-validator";
// ...
validate(post, { skipMissingProperties: true });
When skipping missing properties, sometimes you want not to skip all missing properties, some of them maybe required
for you, even if skipMissingProperties is set to true. For such cases you should use @IsDefined() decorator.
@IsDefined() is the only decorator that ignores skipMissingProperties option.
In different situations you may want to use different validation schemas of the same object. In such cases you can use validation groups.
import {validate, Min, Length} from "class-validator";
export class User {
@Min(12, {
groups: ["registration"]
})
age: number;
@Length(2, 20, {
groups: ["registration", "admin"]
})
name: string;
}
let user = new User();
user.age = 10;
user.name = "Alex";
validate(user, {
groups: ["registration"]
}); // this will not pass validation
validate(user, {
groups: ["admin"]
}); // this will pass validation
validate(user, {
groups: ["registration", "admin"]
}); // this will not pass validation
validate(user, {
groups: []
}); // this will pass validation
There is also a special flag always: true in validation options that you can use. This flag says that this validation
must be applied always no matter which group is used.
If you have custom validation logic you can create a Constraint class:
First create a file, lets say CustomTextLength.ts, and define a new class:
import {ValidatorConstraint, ValidatorConstraintInterface, ValidationArguments} from "class-validator";
@ValidatorConstraint({ name: "customText", async: false })
export class CustomTextLength implements ValidatorConstraintInterface {
validate(text: string, args: ValidationArguments) {
return text.length > 1 && text.length < 10; // for async validations you must return a Promise<boolean> here
}
defaultMessage(args: ValidationArguments) { // here you can provide default error message if validation failed
return "Text ($value) is too short or too long!";
}
}
We marked our class with @ValidatorConstraint decorator.
You can also supply a validation constraint name - this name will be used as "error type" in ValidationError.
If you will not supply a constraint name - it will be auto-generated.
Our class must implement ValidatorConstraintInterface interface and its validate method,
which defines validation logic. If validation succeeds, method returns true, otherwise false.
Custom validator can be asynchronous, if you want to perform validation after some asynchronous
operations, simply return a promise with boolean inside in validate method.
Also we defined optional method defaultMessage which defines a default error message,
in the case that the decorator's implementation doesn't set an error message.
Then you can use your new validation constraint in your class:
import {Validate} from "class-validator";
import {CustomTextLength} from "./CustomTextLength";
export class Post {
@Validate(CustomTextLength, {
message: "Title is too short or long!"
})
title: string;
}
Here we set our newly created CustomTextLength validation constraint for Post.title.
And use validator as usual:
import {validate} from "class-validator";
validate(post).then(errors => {
// ...
});
You can also pass constraints to your validator, like this:
import {Validate} from "class-validator";
import {CustomTextLength} from "./CustomTextLength";
export class Post {
@Validate(CustomTextLength, [3, 20], {
message: "Wrong post title"
})
title: string;
}
And use them from validationArguments object:
import {ValidationArguments, ValidatorConstraint, ValidatorConstraintInterface} from "class-validator";
@ValidatorConstraint()
export class CustomTextLength implements ValidatorConstraintInterface {
validate(text: string, validationArguments: ValidationArguments) {
return text.length > validationArguments.constraints[0] && text.length < validationArguments.constraints[1];
}
}
You can also create a custom decorators. Its the most elegant way of using a custom validations.
Lets create a decorator called @IsLongerThan:
Create a decorator itself:
import {registerDecorator, ValidationOptions, ValidationArguments} from "class-validator";
export function IsLongerThan(property: string, validationOptions?: ValidationOptions) {
return function (object: Object, propertyName: string) {
registerDecorator({
name: "isLongerThan",
target: object.constructor,
propertyName: propertyName,
options: validationOptions,
validator: {
validate(value: any, args: ValidationArguments) {
const [relatedPropertyName] = args.constraints;
const relatedValue = (args.object as any)[relatedPropertyName];
return typeof value === "string" &&
typeof relatedValue === "string" &&
value.length > relatedValue.length; // you can return a Promise<boolean> here as well, if you want to make async validation
}
}
});
};
}
Put it to use:
import {IsLongerThan} from "./IsLongerThan";
export class Post {
title: string;
@IsLongerThan("title", {
/* you can also use additional validation options, like "each", "groups" in your custom validation decorators */
message: "Text must be longer than the title"
})
text: string;
}
In your custom decorators you can also use ValidationConstraint.
Lets create another custom validation decorator called IsUserAlreadyExist:
Create a ValidationConstraint and decorator:
import {registerDecorator, ValidationOptions, ValidatorConstraint, ValidatorConstraintInterface, ValidationArguments} from "class-validator";
@ValidatorConstraint({ async: true })
export class IsUserAlreadyExistConstraint implements ValidatorConstraintInterface {
validate(userName: any, args: ValidationArguments) {
return UserRepository.findOneByName(userName).then(user => {
if (user) return false;
return true;
});
}
}
export function IsUserAlreadyExist(validationOptions?: ValidationOptions) {
return function (object: Object, propertyName: string) {
registerDecorator({
target: object.constructor,
propertyName: propertyName,
options: validationOptions,
constraints: [],
validator: IsUserAlreadyExistConstraint
});
};
}
note that we marked our constraint that it will by async by adding { async: true } in validation options.
And put it to use:
import {IsUserAlreadyExist} from "./IsUserAlreadyExist";
export class User {
@IsUserAlreadyExist({
message: "User $value already exists. Choose another name."
})
name: string;
}
Validator supports service container in the case if want to inject dependencies into your custom validator constraint classes. Here is example how to integrate it with typedi:
import {Container} from "typedi";
import {useContainer, Validator} from "class-validator";
// do this somewhere in the global application level:
useContainer(Container);
let validator = Container.get(Validator);
// now everywhere you can inject Validator class which will go from the container
// also you can inject classes using constructor injection into your custom ValidatorConstraint-s
If you want to perform a simple non async validation you can use validateSync method instead of regular validate
method. It has the same arguments as validate method. But note, this method ignores all async validations
you have.
There are several method exist in the Validator that allows to perform non-decorator based validation:
import {Validator} from "class-validator";
// Validation methods
const validator = new Validator();
// common validation methods
validator.isDefined(value); // Checks if value is defined ("!==undefined").
validator.equals(value, comparison); // Checks if value matches ("===") the comparison.
validator.notEquals(value, comparison); // Checks if value does not match ("!==") the comparison.
validator.isEmpty(value); // Checks if given value is empty (=== '', === null, === undefined).
validator.isNotEmpty(value); // Checks if given value is not empty (!== '', !== null, !== undefined).
validator.isIn(value, possibleValues); // Checks if given value is in a array of allowed values.
validator.isNotIn(value, possibleValues); // Checks if given value not in a array of allowed values.
// type validation methods
validator.isBoolean(value); // Checks if a given value is a real boolean.
validator.isDate(value); // Checks if a given value is a real date.
validator.isString(value); // Checks if a given value is a real string.
validator.isArray(value); // Checks if a given value is an array.
validator.isNumber(value); // Checks if a given value is a real number.
validator.isInt(value); // Checks if value is an integer.
// number validation methods
validator.isDivisibleBy(value, num); // Checks if value is a number that's divisible by another.
validator.isPositive(value); // Checks if the value is a positive number.
validator.isNegative(value); // Checks if the value is a negative number.
validator.max(num, max); // Checks if the first number is greater than second.
validator.min(num, min); // Checks if the first number is less than second.
// date validation methods
validator.minDate(date, minDate); // Checks if the value is a date that's after the specified date.
validator.maxDate(date, minDate); // Checks if the value is a date that's before the specified date.
// string-type validation methods
validator.isBooleanString(str); // Checks if a string is a boolean.
validator.isDateString(str); // Checks if the string is a date.
validator.isNumberString(str); // Checks if the string is numeric.
// string validation methods
validator.contains(str, seed); // Checks if the string contains the seed.
validator.notContains(str, seed); // Checks if the string does not contain the seed.
validator.isAlpha(str); // Checks if the string contains only letters (a-zA-Z).
validator.isAlphanumeric(str); // Checks if the string contains only letters and numbers.
validator.isAscii(str); // Checks if the string contains ASCII chars only.
validator.isBase64(str); // Checks if a string is base64 encoded.
validator.isByteLength(str, min, max); // Checks if the string's length (in bytes) falls in a range.
validator.isCreditCard(str); // Checks if the string is a credit card.
validator.isCurrency(str, options); // Checks if the string is a valid currency amount.
validator.isEmail(str, options); // Checks if the string is an email.
validator.isFQDN(str, options); // Checks if the string is a fully qualified domain name (e.g. domain.com).
validator.isFullWidth(str); // Checks if the string contains any full-width chars.
validator.isHalfWidth(str); // Checks if the string contains any half-width chars.
validator.isVariableWidth(str); // Checks if the string contains variable-width chars.
validator.isHexColor(str); // Checks if the string is a hexadecimal color.
validator.isHexadecimal(str); // Checks if the string is a hexadecimal number.
validator.isIP(str, version); // Checks if the string is an IP (version 4 or 6).
validator.isISBN(str, version); // Checks if the string is an ISBN (version 10 or 13).
validator.isISIN(str); // Checks if the string is an ISIN (stock/security identifier).
validator.isISO8601(str); // Checks if the string is a valid ISO 8601 date.
validator.isJSON(str); // Checks if the string is valid JSON (note: uses JSON.parse).
validator.isLowercase(str); // Checks if the string is lowercase.
validator.isMobilePhone(str, locale); // Checks if the string is a mobile phone number.
validator.isMongoId(str); // Checks if the string is a valid hex-encoded representation of a MongoDB ObjectId.
validator.isMultibyte(str); // Checks if the string contains one or more multibyte chars.
validator.isSurrogatePair(str); // Checks if the string contains any surrogate pairs chars.
validator.isURL(str, options); // Checks if the string is an url.
validator.isUUID(str, version); // Checks if the string is a UUID (version 3, 4 or 5).
validator.isUppercase(str); // Checks if the string is uppercase.
validator.length(str, min, max); // Checks if the string's length falls in a range.
validator.minLength(str, min); // Checks if the string's length is not less than given number.
validator.maxLength(str, max); // Checks if the string's length is not more than given number.
validator.matches(str, pattern, modifiers); // Checks if string matches the pattern. Either matches('foo', /foo/i) or matches('foo', 'foo', 'i').
validator.isMilitaryTime(str); // Checks if the string is a valid representation of military time in the format HH:MM.
// array validation methods
validator.arrayContains(array, values); // Checks if array contains all values from the given array of values.
validator.arrayNotContains(array, values); // Checks if array does not contain any of the given values.
validator.arrayNotEmpty(array); // Checks if given array is not empty.
validator.arrayMinSize(array, min); // Checks if array's length is at least `min` number.
validator.arrayMaxSize(array, max); // Checks if array's length is as most `max` number.
validator.arrayUnique(array); // Checks if all array's values are unique. Comparison for objects is reference-based.
| Decorator | Description |
|---|---|
| Common validation decorators | |
@IsDefined(value: any) | Checks if value is defined (!== undefined, !== null). This is the only decorator that ignores skipMissingProperties option. |
@Equals(comparison: any) | Checks if value equals ("===") comparison. |
@NotEquals(comparison: any) | Checks if value not equal ("!==") comparison. |
@IsEmpty() | Checks if given value is empty (=== '', === null, === undefined). |
@IsNotEmpty() | Checks if given value is not empty (!== '', !== null, !== undefined). |
@IsIn(values: any[]) | Checks if value is in a array of allowed values. |
@IsNotIn(values: any[]) | Checks if value is not in a array of disallowed values. |
| Type validation decorators | |
@IsBoolean() | Checks if a value is a boolean. |
@IsDate() | Checks if the string is a date. |
@IsString() | Checks if the string is a string. |
@IsNumber() | Checks if the string is a number. |
@IsInt() | Checks if the value is an integer number. |
@IsArray() | Checks if the string is an array |
| Number validation decorators | |
@IsDivisibleBy(num: number) | Checks if the value is a number that's divisible by another. |
@IsPositive() | Checks if the value is a positive number. |
@IsNegative() | Checks if the value is a negative number. |
@Max(max: number) | Checks if the given number is greater than given number. |
@Min(min: number) | Checks if the given number is less than given number. |
| Date validation decorators | |
@MinDate(date: Date) | Checks if the value is a date that's after the specified date. |
@MaxDate(date: Date) | Checks if the value is a date that's before the specified date. |
| String-type validation decorators | |
@IsBooleanString() | Checks if a string is a boolean (e.g. is "true" or "false"). |
@IsDateString() | Checks if a string is a date. |
@IsNumberString() | Checks if a string is a number. |
| String validation decorators | |
@Contains(seed: string) | Checks if the string contains the seed. |
@NotContains(seed: string) | Checks if the string not contains the seed. |
@IsAlpha() | Checks if the string contains only letters (a-zA-Z). |
@IsAlphanumeric() | Checks if the string contains only letters and numbers. |
@IsAscii() | Checks if the string contains ASCII chars only. |
@IsBase64() | Checks if a string is base64 encoded. |
@IsByteLength(min: number, max?: number) | Checks if the string's length (in bytes) falls in a range. |
@IsCreditCard() | Checks if the string is a credit card. |
@IsCurrency(options?: IsCurrencyOptions) | Checks if the string is a valid currency amount. |
@IsEmail(options?: IsEmailOptions) | Checks if the string is an email. |
@IsFQDN(options?: IsFQDNOptions) | Checks if the string is a fully qualified domain name (e.g. domain.com). |
@IsFullWidth() | Checks if the string contains any full-width chars. |
@IsHalfWidth() | Checks if the string contains any half-width chars. |
@IsVariableWidth() | Checks if the string contains a mixture of full and half-width chars. |
@IsHexColor() | Checks if the string is a hexadecimal color. |
@IsHexadecimal() | Checks if the string is a hexadecimal number. |
| `@IsIP(version?: "4" | "6")` |
| `@IsISBN(version?: "10" | "13")` |
@IsISIN() | Checks if the string is an ISIN (stock/security identifier). |
@IsISO8601() | Checks if the string is a valid ISO 8601 date. |
@IsJSON() | Checks if the string is valid JSON. |
@IsLowercase() | Checks if the string is lowercase. |
@IsMobilePhone(locale: string) | Checks if the string is a mobile phone number. |
@IsMongoId() | Checks if the string is a valid hex-encoded representation of a MongoDB ObjectId. |
@IsMultibyte() | Checks if the string contains one or more multibyte chars. |
@IsNumericString() | Checks if the string is numeric. |
@IsSurrogatePair() | Checks if the string contains any surrogate pairs chars. |
@IsUrl(options?: IsURLOptions) | Checks if the string is an url. |
| `@IsUUID(version?: "3" | "4" |
@IsUppercase() | Checks if the string is uppercase. |
@Length(min: number, max?: number) | Checks if the string's length falls in a range. |
@MinLength(min: number) | Checks if the string's length is not less than given number. |
@MaxLength(max: number) | Checks if the string's length is not more than given number. |
@Matches(pattern: RegExp, modifiers?: string) | Checks if string matches the pattern. Either matches('foo', /foo/i) or matches('foo', 'foo', 'i'). |
@IsMilitaryTime() | Checks if the string is a valid representation of military time in the format HH:MM. |
| Array validation decorators | |
@ArrayContains(values: any[]) | Checks if array contains all values from the given array of values. |
@ArrayNotContains(values: any[]) | Checks if array does not contain any of the given values. |
@ArrayNotEmpty() | Checks if given array is not empty. |
@ArrayMinSize(min: number) | Checks if array's length is as minimal this number. |
@ArrayMaxSize(max: number) | Checks if array's length is as maximal this number. |
@ArrayUnique() | Checks if all array's values are unique. Comparison for objects is reference-based. |
You can define your validation schemas without decorators:
.json fileThis feature maybe useful in the cases if:
Here is an example of using it:
Create a schema object:
import {ValidationSchema} from "class-validator";
export let UserValidationSchema: ValidationSchema = { // using interface here is not required, its just for type-safety
name: "myUserSchema", // this is required, and must be unique
properties: {
firstName: [{
type: "minLength", // validation type. All validation types are listed in ValidationTypes class.
constraints: [2]
}, {
type: "maxLength",
constraints: [20]
}],
lastName: [{
type: "minLength",
constraints: [2]
}, {
type: "maxLength",
constraints: [20]
}],
email: [{
type: "isEmail"
}]
}
};
Same schema can be provided in .json file, depend on your wish.
Register your schema:
import {registerSchema} from "class-validator";
import {UserValidationSchema} from "./UserValidationSchema";
registerSchema(schema); // if schema is in .json file, then you can simply do registerSchema(require("path-to-schema.json"));
Better to put this code in a global place, maybe when you bootstrap your application, for example in app.ts.
Validate your object using validation schema:
import {validate} from "class-validator";
const user = { firstName: "Johny", secondName: "Cage", email: "johny@cage.com" };
validate("myUserSchema", user).then(errors => {
if (errors.length > 0) {
console.log("Validation failed: ", errors);
} else {
console.log("Validation succeed.");
}
});
That's it. Here "myUserSchema" is the name of our validation schema.
validate method will perform validation based on this schema
Take a look on samples in ./sample for more examples of usages.
See information about breaking changes and release notes here.
0.6.7
@ValidateNested when nested property is not defined and it throw an error (#59)FAQs
Decorator-based property validation for classes.
The npm package class-validator receives a total of 2,540,027 weekly downloads. As such, class-validator popularity was classified as popular.
We found that class-validator demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
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