wp_ajax_upload_attachment()

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Performance profile

How much work a call to wp_ajax_upload_attachment() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Heavy

Reaches the database via get_post().

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

48–197

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 199.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

0

Nothing in core calls this; the cost is only what you spend yourself.

What it touches

• hookthird-party callbacksdo_action()one call below wp_ajax_upload_attachment()
• querycontent queryget_post()one call below wp_ajax_upload_attachment()

Further down the call graph this can also reach option, serialize, cache and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 864 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost wp_ajax_upload_attachment() can have, taken from its control-flow graph on PHP 8.5.

Uses · 14

• check_ajax_referer()Verifies the Ajax request to prevent processing requests external of the blog.
• current_user_can()Returns whether the current user has the specified capability.
• wp_json_encode()Encodes a variable into JSON, with some confidence checks.
• __()Retrieves the translation of $text.
• esc_html()Escaping for HTML blocks.
• wp_die()Kills WordPress execution and displays HTML page with an error message.
• _wp_get_allowed_postdata()Returns only allowed post data fields.
• _wp_translate_postdata()Renames `$_POST` data from form names to DB post columns.
• is_wp_error()Checks whether the given variable is a WordPress Error.
• wp_check_filetype_and_ext()Attempts to determine the real file type of a file.
• wp_match_mime_types()Checks a MIME-Type against a list.
• media_handle_upload()Saves a file submitted from a POST request and create an attachment post for it.

Source code

View on Trac ↗View on GitHub ↗

2565function wp_ajax_upload_attachment() {2566	check_ajax_referer( 'media-form' );2567	/*2568	 * This function does not use wp_send_json_success() / wp_send_json_error()2569	 * as the html4 Plupload handler requires a text/html Content-Type for older IE.2570	 * See https://core.trac.wordpress.org/ticket/310372571	 */2572 2573	if ( ! current_user_can( 'upload_files' ) ) {2574		echo wp_json_encode(2575			array(2576				'success' => false,2577				'data'    => array(2578					'message'  => __( 'Sorry, you are not allowed to upload files.' ),2579					'filename' => esc_html( $_FILES['async-upload']['name'] ),2580				),2581			)2582		);2583 2584		wp_die();2585	}2586 2587	if ( isset( $_REQUEST['post_id'] ) ) {2588		$post_id = $_REQUEST['post_id'];2589 2590		if ( ! current_user_can( 'edit_post', $post_id ) ) {2591			echo wp_json_encode(2592				array(2593					'success' => false,2594					'data'    => array(2595						'message'  => __( 'Sorry, you are not allowed to attach files to this post.' ),2596						'filename' => esc_html( $_FILES['async-upload']['name'] ),2597					),2598				)2599			);2600 2601			wp_die();2602		}2603	} else {2604		$post_id = null;2605	}2606 2607	$post_data = ! empty( $_REQUEST['post_data'] ) ? _wp_get_allowed_postdata( _wp_translate_postdata( false, (array) $_REQUEST['post_data'] ) ) : array();2608 2609	if ( is_wp_error( $post_data ) ) {2610		wp_die( $post_data->get_error_message() );2611	}2612 2613	// If the context is custom header or background, make sure the uploaded file is an image.2614	if ( isset( $post_data['context'] ) && in_array( $post_data['context'], array( 'custom-header', 'custom-background' ), true ) ) {2615		$wp_filetype = wp_check_filetype_and_ext( $_FILES['async-upload']['tmp_name'], $_FILES['async-upload']['name'] );2616 2617		if ( ! wp_match_mime_types( 'image', $wp_filetype['type'] ) ) {2618			echo wp_json_encode(2619				array(2620					'success' => false,2621					'data'    => array(2622						'message'  => __( 'The uploaded file is not a valid image. Please try again.' ),2623						'filename' => esc_html( $_FILES['async-upload']['name'] ),2624					),2625				)2626			);2627 2628			wp_die();2629		}2630	}2631 2632	$attachment_id = media_handle_upload( 'async-upload', $post_id, $post_data );2633 2634	if ( is_wp_error( $attachment_id ) ) {2635		echo wp_json_encode(2636			array(2637				'success' => false,2638				'data'    => array(2639					'message'  => $attachment_id->get_error_message(),2640					'filename' => esc_html( $_FILES['async-upload']['name'] ),2641				),2642			)2643		);2644

Changelog

Introduced in 3.3.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 6.7.7 tag, from src/wp-admin/includes/ajax-actions.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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