WP_Ajax_Response
Send XML response back to Ajax request.
More Information
Role of WP_Ajax_Response
WP_Ajax_Response is WordPress’ class for generating XML-formatted responses to Ajax requests. This is most commonly used to generate responses to custom AJAX actions when using the wp_ajax_ action hook.
Methods and Properties
NOTE: Refer source code for the complete methods and properties.
Properties
- $responses()
- An array that stores the XML responses to be sent.
Usage
To use WP_Ajax_Response, you need to instantiate the class with an array of options, then call the instances send()
method to output the response.
The options array takes the following key=>value pairs:
- ‘what’
- A string containing the XMLRPC response type (used as the name of the xml element).
- ‘action’
- A boolean or string that will behave like a nonce. This is added to the response element’s action attribute.
- ‘id’
- This is either an integer (usually 1) or a WP_Error object (if you need to return an error). Most commonly, the id value is used as a boolean, where 1 is a success and 0 is a failure.
- ‘old_id’
- This is
false
by default, but you can alternatively provide an integer for the previous id, if needed. - ‘position’
- This is an integer or a string where -1 = top, 1 = bottom, ‘html ID’ = after, ‘-html ID’ = before
- ‘data’
- A string containing output content or a message (such as html). This is disregarded if you pass a WP_Error object as the id.
- ‘supplemental’
- This can an associative array of strings, which will be rendered into children of the
<supplemental>
element. Keys become element names, and values are embedded in CDATA within those elements. Useful for passing additional information to the browser.
Response Format
Responses are made in the XML-RPC format and may be handled by JavaScript.
A typical WordPress autosave response looks like this:
<?xml version='1.0' standalone='yes'?> <wp_ajax> <response action='autosave_1'> <autosave id='1' position='1'> <response_data> <![CDATA[Draft saved at 9:31:55 pm.]]> </response_data> <supplemental></supplemental> </autosave> </response> </wp_ajax>
Let’s break this example down to see what it means:
- <wp_ajax>
- This the root element of every response. All responses made by the WP_Ajax_Response class are wrapped in the
<wp_ajax>
element.
- <response>
- Immediately within the wp_ajax element is
<response>
, which contains the attributes ‘action’ and ‘position’. These attributes correspond to the ‘action’ and ‘position’ key=>value pairs defined in the options array.
- <autosave> (arbitrary)
- Next, the above example shows an
<autosave>
element – this element matches the value of the ‘what’ key=>value pair in the options array. In your own use, this element can be named whatever you like, provided it is a valid XML element name.
- <response_data> / <wp_error_data>
- Within the custom response element (e.g.
<autosave>
), there will either be a<response_data>
element (with CDATA tag) or a<wp_error_data>
element. If you pass a WP_Error object to WP_Ajax_Response as the ‘id’ in your options array, the<wp_error_data>
element is automatically generated. Otherwise, the<response_data>
element is used with whatever value you passed to WP_Ajax_Response with your option array’s “data” value.
- For the most part, any content you want to pass back to the browser (such as HTML), can be passed in your option array’s “data” key=>value pair.
- <supplemental>
- Finally, the
<supplemental>
element will contain whatever arbitrary structure you decide to pass along with your option array’s “supplemental” key=>value pair.
Source
File: wp-includes/class-wp-ajax-response.php
class WP_Ajax_Response { /** * Store XML responses to send. * * @since 2.1.0 * @var array */ public $responses = array(); /** * Constructor - Passes args to WP_Ajax_Response::add(). * * @since 2.1.0 * * @see WP_Ajax_Response::add() * * @param string|array $args Optional. Will be passed to add() method. */ public function __construct( $args = '' ) { if ( ! empty( $args ) ) { $this->add( $args ); } } /** * Appends data to an XML response based on given arguments. * * With `$args` defaults, extra data output would be: * * <response action='{$action}_$id'> * <$what id='$id' position='$position'> * <response_data><![CDATA[$data]]></response_data> * </$what> * </response> * * @since 2.1.0 * * @param string|array $args { * Optional. An array or string of XML response arguments. * * @type string $what XML-RPC response type. Used as a child element of `<response>`. * Default 'object' (`<object>`). * @type string|false $action Value to use for the `action` attribute in `<response>`. Will be * appended with `_$id` on output. If false, `$action` will default to * the value of `$_POST['action']`. Default false. * @type int|WP_Error $id The response ID, used as the response type `id` attribute. Also * accepts a `WP_Error` object if the ID does not exist. Default 0. * @type int|false $old_id The previous response ID. Used as the value for the response type * `old_id` attribute. False hides the attribute. Default false. * @type string $position Value of the response type `position` attribute. Accepts 1 (bottom), * -1 (top), HTML ID (after), or -HTML ID (before). Default 1 (bottom). * @type string|WP_Error $data The response content/message. Also accepts a WP_Error object if the * ID does not exist. Default empty. * @type array $supplemental An array of extra strings that will be output within a `<supplemental>` * element as CDATA. Default empty array. * } * @return string XML response. */ public function add( $args = '' ) { $defaults = array( 'what' => 'object', 'action' => false, 'id' => '0', 'old_id' => false, 'position' => 1, 'data' => '', 'supplemental' => array(), ); $parsed_args = wp_parse_args( $args, $defaults ); $position = preg_replace( '/[^a-z0-9:_-]/i', '', $parsed_args['position'] ); $id = $parsed_args['id']; $what = $parsed_args['what']; $action = $parsed_args['action']; $old_id = $parsed_args['old_id']; $data = $parsed_args['data']; if ( is_wp_error( $id ) ) { $data = $id; $id = 0; } $response = ''; if ( is_wp_error( $data ) ) { foreach ( (array) $data->get_error_codes() as $code ) { $response .= "<wp_error code='$code'><![CDATA[" . $data->get_error_message( $code ) . ']]></wp_error>'; $error_data = $data->get_error_data( $code ); if ( ! $error_data ) { continue; } $class = ''; if ( is_object( $error_data ) ) { $class = ' class="' . get_class( $error_data ) . '"'; $error_data = get_object_vars( $error_data ); } $response .= "<wp_error_data code='$code'$class>"; if ( is_scalar( $error_data ) ) { $response .= "<![CDATA[$error_data]]>"; } elseif ( is_array( $error_data ) ) { foreach ( $error_data as $k => $v ) { $response .= "<$k><![CDATA[$v]]></$k>"; } } $response .= '</wp_error_data>'; } } else { $response = "<response_data><![CDATA[$data]]></response_data>"; } $s = ''; if ( is_array( $parsed_args['supplemental'] ) ) { foreach ( $parsed_args['supplemental'] as $k => $v ) { $s .= "<$k><![CDATA[$v]]></$k>"; } $s = "<supplemental>$s</supplemental>"; } if ( false === $action ) { $action = $_POST['action']; } $x = ''; $x .= "<response action='{$action}_$id'>"; // The action attribute in the xml output is formatted like a nonce action. $x .= "<$what id='$id' " . ( false === $old_id ? '' : "old_id='$old_id' " ) . "position='$position'>"; $x .= $response; $x .= $s; $x .= "</$what>"; $x .= '</response>'; $this->responses[] = $x; return $x; } /** * Display XML formatted responses. * * Sets the content type header to text/xml. * * @since 2.1.0 */ public function send() { header( 'Content-Type: text/xml; charset=' . get_option( 'blog_charset' ) ); echo "<?xml version='1.0' encoding='" . get_option( 'blog_charset' ) . "' standalone='yes'?><wp_ajax>"; foreach ( (array) $this->responses as $response ) { echo $response; } echo '</wp_ajax>'; if ( wp_doing_ajax() ) { wp_die(); } else { die(); } } }
Methods
- __construct — Constructor - Passes args to WP_Ajax_Response::add().
- __get — Make private properties readable for backwards compatibility.
- __isset — Make private properties checkable for backwards compatibility.
- __set — Make private properties settable for backwards compatibility.
- __unset — Make private properties un-settable for backwards compatibility.
- add — Appends data to an XML response based on given arguments.
- send — Display XML formatted responses.
Changelog
Version | Description |
---|---|
2.1.0 | Introduced. |
© 2003–2021 WordPress Foundation
Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/classes/wp_ajax_response