Rule object

Describes how to validate the field. This object is supposed to be passed in addField method. All possible rules listed here.

The object contains several properties/methods:

rule

A rule string (listed here).

Type: string

Example:

{
  rule: 'required',
}

value

For some rules (like minLength, minNumber, customRegexp etc.) it's required to define some value to check against.

Type:

• number
• string
• RegExp
• { files: object } (needed for files validation, please check here)

Example:

[
  {
    rule: 'minLength',
    value: 3,
  },
  {
    rule: 'maxLength',
    value: 15,
  },
];

errorMessage

Error string or a function

Type:

• string
• function, returning a string: (value, context) => string

Example:

{
    errorMessage: 'Invalid field',
}

validator

A validator makes it possible to write your own custom validation rule. For general sync validation this is just a function that returns if the field valid or not (true or false), based on a field's value. For async validations you could return a function, that should return a promise with true or false value.

Type:

• (value, context) => boolean
• (value, context) => () => Promise<boolean>

Example:

{
    validator: (value, context) => value === '20' ? false : true,
}

or

{
  validator: (value, context) => () =>
    new Promise((resolve) => {
      setTimeout(() => {
        resolve(false);
      }, 1000);
    }),
}