yiminghe/ async-validator

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yiminghe

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validate form asynchronous

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async-validator

Name: async-validator
Brand: async-validator
SKU: //yiminghe/async-validator
Rating: 4.6066666666666665 (6460 reviews)

Validate form asynchronous. A variation of https://github.com/freeformsystems/async-validate

Install

npm i async-validator

Usage

Basic usage involves defining a descriptor, assigning it to a schema and passing the object to be validated and a callback function to the

validate

method of the schema:

import Schema from 'async-validator';
const descriptor = {
  name: {
    type: 'string',
    required: true,
    validator: (rule, value) => value === 'muji',
  },
  age: {
    type: 'number',
    asyncValidator: (rule, value) => {
      return new Promise((resolve, reject) => {
        if (value < 18) {
          reject('too young');  // reject with error message
        } else {
          resolve();
        }
      });
    },
  },
};
const validator = new Schema(descriptor);
validator.validate({ name: 'muji' }, (errors, fields) => {
  if (errors) {
    // validation failed, errors is an array of all errors
    // fields is an object keyed by field name with an array of
    // errors per field
    return handleErrors(errors, fields);
  }
  // validation passed
});

// PROMISE USAGE
validator.validate({ name: 'muji', age: 16 }).then(() => {
  // validation passed or without error message
}).catch(({ errors, fields }) => {
  return handleErrors(errors, fields);
});

API

Validate

function(source, [options], callback): Promise

```
source
```
: The object to validate (required).
```
options
```
: An object describing processing options for the validation (optional).
```
callback
```
: A callback function to invoke when validation completes (required).

The method will return a Promise object like: *

then()

，validation passed *

catch({ errors, fields })

，validation failed, errors is an array of all errors, fields is an object keyed by field name with an array of

Options

```
suppressWarning
```
: Boolean, whether to suppress internal warning about invalid value.
```
first
```
: Boolean, Invoke
```
callback
```
when the first validation rule generates an error, no more validation rules are processed. If your validation involves multiple asynchronous calls (for example, database queries) and you only need the first error use this option.
```
firstFields
```
: Boolean|String[], Invoke
```
callback
```
when the first validation rule of the specified field generates an error, no more validation rules of the same field are processed.
```
true
```
means all fields.

Rules

Rules may be functions that perform validation.

function(rule, value, callback, source, options)

```
rule
```
: The validation rule in the source descriptor that corresponds to the field name being validated. It is always assigned a
```
field
```
property with the name of the field being validated.
```
value
```
: The value of the source object property being validated.
```
callback
```
: A callback function to invoke once validation is complete. It expects to be passed an array of
```
Error
```
instances to indicate validation failure. If the check is synchronous, you can directly return a
```
false
```
or
```
Error
```
or
```
Error Array
```
.
```
source
```
: The source object that was passed to the
```
validate
```
method.
```
options
```
: Additional options.
```
options.messages
```
: The object containing validation error messages, will be deep merged with defaultMessages.

The options passed to

validate

asyncValidate

are passed on to the validation functions so that you may reference transient data (such as model references) in validation functions. However, some option names are reserved; if you use these properties of the options object they are overwritten. The reserved properties are

messages

exception

and

error

import Schema from 'async-validator';
const descriptor = {
  name(rule, value, callback, source, options) {
    const errors = [];
    if (!/^[a-z0-9]+$/.test(value)) {
      errors.push(new Error(
        util.format('%s must be lowercase alphanumeric characters', rule.field),
      ));
    }
    return errors;
  },
};
const validator = new Schema(descriptor);
validator.validate({ name: 'Firstname' }, (errors, fields) => {
  if (errors) {
    return handleErrors(errors, fields);
  }
  // validation passed
});

It is often useful to test against multiple validation rules for a single field, to do so make the rule an array of objects, for example:

const descriptor = {
  email: [
    { type: 'string', required: true, pattern: Schema.pattern.email },
    { 
      validator(rule, value, callback, source, options) {
        const errors = [];
        // test if email address already exists in a database
        // and add a validation error to the errors array if it does
        return errors;
      },
    },
  ],
};

Type

Indicates the

type

of validator to use. Recognised type values are:

```
string
```
: Must be of type
```
string
```
.
```
This is the default type.
```
```
number
```
: Must be of type
```
number
```
.
```
boolean
```
: Must be of type
```
boolean
```
.
```
method
```
: Must be of type
```
function
```
.
```
regexp
```
: Must be an instance of
```
RegExp
```
or a string that does not generate an exception when creating a new
```
RegExp
```
.
```
integer
```
: Must be of type
```
number
```
and an integer.
```
float
```
: Must be of type
```
number
```
and a floating point number.
```
array
```
: Must be an array as determined by
```
Array.isArray
```
.
```
object
```
: Must be of type
```
object
```
and not
```
Array.isArray
```
.
```
enum
```
: Value must exist in the
```
enum
```
.
```
date
```
: Value must be valid as determined by
```
Date
```
```
url
```
: Must be of type
```
url
```
.
```
hex
```
: Must be of type
```
hex
```
.
```
email
```
: Must be of type
```
email
```
.
```
any
```
: Can be any type.

Required

The

required

rule property indicates that the field must exist on the source object being validated.

Pattern

The

pattern

rule property indicates a regular expression that the value must match to pass validation.

Range

A range is defined using the

min

and

max

properties. For

string

and

array

types comparison is performed against the

length

, for

number

types the number must not be less than

min

nor greater than

max

Length

To validate an exact length of a field specify the

len

property. For

string

and

array

types comparison is performed on the

length

property, for the

number

type this property indicates an exact match for the

number

, ie, it may only be strictly equal to

len

If the

len

property is combined with the

min

and

max

range properties,

len

takes precedence.

Enumerable

Since version 3.0.0 if you want to validate the values
0
or
false
inside
enum
types, you have to include them explicitly.

To validate a value from a list of possible values use the

enum

type with a

enum

property listing the valid values for the field, for example:

const descriptor = {
  role: { type: 'enum', enum: ['admin', 'user', 'guest'] },
};

Whitespace

It is typical to treat required fields that only contain whitespace as errors. To add an additional test for a string that consists solely of whitespace add a

whitespace

property to a rule with a value of

true

. The rule must be a

string

type.

You may wish to sanitize user input instead of testing for whitespace, see transform for an example that would allow you to strip whitespace.

Deep Rules

If you need to validate deep object properties you may do so for validation rules that are of the

object

array

type by assigning nested rules to a

fields

property of the rule.

const descriptor = {
  address: {
    type: 'object',
    required: true,
    fields: {
      street: { type: 'string', required: true },
      city: { type: 'string', required: true },
      zip: { type: 'string', required: true, len: 8, message: 'invalid zip' },
    },
  },
  name: { type: 'string', required: true },
};
const validator = new Schema(descriptor);
validator.validate({ address: {} }, (errors, fields) => {
  // errors for address.street, address.city, address.zip
});

Note that if you do not specify the

required

property on the parent rule it is perfectly valid for the field not to be declared on the source object and the deep validation rules will not be executed as there is nothing to validate against.

Deep rule validation creates a schema for the nested rules so you can also specify the

options

passed to the

schema.validate()

method.

const descriptor = {
  address: {
    type: 'object',
    required: true,
    options: { first: true },
    fields: {
      street: { type: 'string', required: true },
      city: { type: 'string', required: true },
      zip: { type: 'string', required: true, len: 8, message: 'invalid zip' },
    },
  },
  name: { type: 'string', required: true },
};
const validator = new Schema(descriptor);

validator.validate({ address: {} })
  .catch(({ errors, fields }) => {
    // now only errors for street and name
  });

The parent rule is also validated so if you have a set of rules such as:

const descriptor = {
  roles: {
    type: 'array',
    required: true,
    len: 3,
    fields: {
      0: { type: 'string', required: true },
      1: { type: 'string', required: true },
      2: { type: 'string', required: true },
    },
  },
};

And supply a source object of

{ roles: ['admin', 'user'] }

then two errors will be created. One for the array length mismatch and one for the missing required array entry at index 2.

defaultField

The

defaultField

property can be used with the

array

object

type for validating all values of the container. It may be an

object

array

containing validation rules. For example:

const descriptor = {
  urls: {
    type: 'array',
    required: true,
    defaultField: { type: 'url' },
  },
};

Note that

defaultField

is expanded to

fields

, see deep rules.

Transform

Sometimes it is necessary to transform a value before validation, possibly to coerce the value or to sanitize it in some way. To do this add a

transform

function to the validation rule. The property is transformed prior to validation and re-assigned to the source object to mutate the value of the property in place.

import Schema from 'async-validator';
const descriptor = {
  name: {
    type: 'string',
    required: true,
    pattern: /^[a-z]+$/,
    transform(value) {
      return value.trim();
    },
  },
};
const validator = new Schema(descriptor);
const source = { name: ' user  ' };
validator.validate(source)
  .then(() => assert.equal(source.name, 'user'));

Without the

transform

function validation would fail due to the pattern not matching as the input contains leading and trailing whitespace, but by adding the transform function validation passes and the field value is sanitized at the same time.

Messages

Depending upon your application requirements, you may need i18n support or you may prefer different validation error messages.

The easiest way to achieve this is to assign a

message

to a rule:

{ name: { type: 'string', required: true, message: 'Name is required' } }

Message can be any type, such as jsx format.

{ name: { type: 'string', required: true, message: 'Name is required' } }

Message can also be a function, e.g. if you use vue-i18n:

js
{ name: { type: 'string', required: true, message: () => this.$t( 'name is required' ) } }

Potentially you may require the same schema validation rules for different languages, in which case duplicating the schema rules for each language does not make sense.

In this scenario you could just provide your own messages for the language and assign it to the schema:

import Schema from 'async-validator';
const cn = {
  required: '%s 必填',
};
const descriptor = { name: { type: 'string', required: true } };
const validator = new Schema(descriptor);
// deep merge with defaultMessages
validator.messages(cn);
...

If you are defining your own validation functions it is better practice to assign the message strings to a messages object and then access the messages via the

options.messages

property within the validation function.

asyncValidator

You can customize the asynchronous validation function for the specified field:

const fields = {
  asyncField: {
    asyncValidator(rule, value, callback) {
      ajax({
        url: 'xx',
        value: value,
      }).then(function(data) {
        callback();
      }, function(error) {
        callback(new Error(error));
      });
    },
  },

  promiseField: {
    asyncValidator(rule, value) {
      return ajax({
        url: 'xx',
        value: value,
      });
    },
  },
};

validator

You can custom validate function for specified field:

const fields = {
  field: {
    validator(rule, value, callback) {
      return value === 'test';
    },
    message: 'Value is not equal to "test".',
  },

  field2: {
    validator(rule, value, callback) {
      return new Error(${value} is not equal to 'test'.);
    },
  },
  arrField: {
    validator(rule, value) {
      return [
        new Error('Message 1'),
        new Error('Message 2'),
      ];
    },
  },
};

FAQ

How to avoid warning

import Schema from 'async-validator';
Schema.warning = function(){};

How to check if it is

true

Use

enum

type passing

true

as option.

{
  type: 'enum',
  enum: [true],
  message: '',
}

Test Case

npm test

Coverage

npm run coverage

Open coverage/ dir

License

Everything is MIT.