Validation

Overview

The Meta Box plugin has built-in validation module for all fields. You can use validation to make a field required, check password length, check phone number format, etc.

The validation module is built with the popular jQuery validation plugin which makes client side form validation easy, whilst still offering plenty of customization options. The plugin comes bundled with a useful set of validation methods and an API to write your own methods. All bundled methods come with default error messages in English and translations into 37 other languages.

Validation rules

To start using validation in Meta Box, you need to add a key validation to the meta box settings. This key has a parameter rules for validation rules and messages for error messages.

Let’s look at the example:

'validation' => array(
    'rules'  => array(
        'field_id' => array(
            'required'  => true,
            'minlength' => 7,
            // More rules here
        ),
        // Rules for other fields
    ),
)

This example add validation for field_id field. There are 2 validation rules for this field: field is required and minimum length is 7.

So, basically the format for rules is:

'rules' => array(
    'field_id_1' => array(
         // rules for field_id_1
    ),
    'field_id_2' => array(
         // rules for field_id_2
    ),
    // Rules for other fields
),

Built-in validation rules

These are list of basic validation rules that you can use for your fields:

Name	Description
`required`	Makes the element required.
`minlength`	Makes the element require a given minimum length.
`maxlength`	Makes the element require a given maxmimum length.
`rangelength`	Makes the element require a given value range. Array.
`min`	Makes the element require a given minimum.
`max`	Makes the element require a given maximum.
`range`	Makes the element require a given value range. Array.
`email`	Makes the element require a valid email
`url`	Makes the element require a valid url
`date`	Makes the element require a date.
`dateISO`	Makes the element require an ISO date.
`number`	Makes the element require a decimal number.
`digits`	Makes the element require digits only.
`creditcard`	Makes the element require a credit card number.
`equalTo`	Requires the element to be the same as another one. Value must be the ID of another field.
`remote`	Requests a resource to check the element for validity. Value can be URL of the resource to request for server side validation (string) or options to fully customize the request, see jQuery.ajax. The server side resource is called via jQuery.ajax and gets a key/value pair corresponding to the name of the validated element and its value as a GET parameter. The response is evaluated as JSON and must be `true` for valid elements, and can be any `false`, `undefined` or `null` for invalid elements, using the default message; or a string, eg. “That name is already taken, try peter123 instead” to display as the error message.

For more details about validation rules, please read the jQuery validation documentation.

Error messages

To use custom error messages, you can add another parameter messages for validation key. This parameter has the same format as rules, but it just contains error messages for each rule.

Look at the example below:

'validation' => array(
    'rules'  => array(
        'field_id' => array(
            'required'  => true,
            'minlength' => 7,
        ),
    ),
    // Optional override of default error messages
    'messages' => array(
        'field_id' => array(
            'required'  => 'Password is required',
            'minlength' => 'Password must be at least 7 characters',
        ),
    )
)