WP_Ajax_Response
Send XML response back to Ajax request.
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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
falseby 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();
}
}
}
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Methods
- __construct — Constructor - Passes args to WP_Ajax_Response::add().
- add — Appends data to an XML response based on given arguments.
- send — Display XML formatted responses.
Changelog
| Version | Description |
|---|---|
| 2.1.0 | Introduced. |
User Contributed Notes
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Typical Response Example
This demonstrates a typical response. The first code block shows the PHP required to create a simple response. The second code block shows the generated XML.
The above example would output the following XML:
<?xml version='1.0' standalone='yes'?> <wp_ajax> <response action='update_something_1'> <foobar id='1' position='1'> <response_data><![CDATA[<p><strong>Hello world!</strong></p>]]></response_data> <supplemental></supplemental> </foobar> </response> </wp_ajax>Error Response Example from Codex
This demonstrates a typical error response. The first code block shows the PHP required to generate such a response, and the second code block shows the generated XML output. Note that you can just as easily give your response an id of 0 instead of generating a new WP_Error. The choice is up to you.
$response = array( 'what'=>'stuff', 'action'=>'delete_something', 'id'=>new WP_Error('oops','I had an accident.'), 'data'=>'Whoops, there was a problem!' ); $xmlResponse = new WP_Ajax_Response($response); $xmlResponse->send();The above example would output the following XML:
<?xml version='1.0' standalone='yes'?> <wp_ajax> <response action='delete_something_0'> <stuff id='0' position='1'> <wp_error code='oops'><![CDATA[I had an accident.]]></wp_error> <supplemental></supplemental> </stuff> </response> </wp_ajax>Note how this response completely disregards our ‘data’ value.