Defined (1)

The function is defined in the following location(s).

/wp-admin/includes/template.php  

function meta_form( $post = null ) { 
    global $wpdb; 
    $post = get_post( $post ); 
 
    /** 
     * Filters values for the meta key dropdown in the Custom Fields meta box. 
     * 
     * Returning a non-null value will effectively short-circuit and avoid a 
     * potentially expensive query against postmeta. 
     * 
     * @since 4.4.0 
     * 
     * @param array|null $keys Pre-defined meta keys to be used in place of a postmeta query. Default null. 
     * @param WP_Post    $post The current post object. 
     */ 
    $keys = apply_filters( 'postmeta_form_keys', null, $post ); 
 
    if ( null === $keys ) { 
        /** 
         * Filters the number of custom fields to retrieve for the drop-down 
         * in the Custom Fields meta box. 
         * 
         * @since 2.1.0 
         * 
         * @param int $limit Number of custom fields to retrieve. Default 30. 
         */ 
        $limit = apply_filters( 'postmeta_form_limit', 30 ); 
        $sql = "SELECT DISTINCT meta_key 
            FROM $wpdb->postmeta 
            WHERE meta_key NOT BETWEEN '_' AND '_z' 
            HAVING meta_key NOT LIKE %s 
            ORDER BY meta_key 
            LIMIT %d"; 
        $keys = $wpdb->get_col( $wpdb->prepare( $sql, $wpdb->esc_like( '_' ) . '%', $limit ) ); 
    } 
 
    if ( $keys ) { 
        natcasesort( $keys ); 
        $meta_key_input_id = 'metakeyselect'; 
    } else { 
        $meta_key_input_id = 'metakeyinput'; 
    } 
?> 
<p><strong><?php _e( 'Add New Custom Field:' ) ?></strong></p> 
<table id="newmeta"> 
<thead> 
<tr> 
<th class="left"><label for="<?php echo $meta_key_input_id; ?>"><?php _ex( 'Name', 'meta name' ) ?></label></th> 
<th><label for="metavalue"><?php _e( 'Value' ) ?></label></th> 
</tr> 
</thead> 
 
<tbody> 
<tr> 
<td id="newmetaleft" class="left"> 
<?php if ( $keys ) { ?> 
<select id="metakeyselect" name="metakeyselect"> 
<option value="#NONE#"><?php _e( '— Select —' ); ?></option> 
<?php 
 
    foreach ( $keys as $key ) { 
        if ( is_protected_meta( $key, 'post' ) || ! current_user_can( 'add_post_meta', $post->ID, $key ) ) 
            continue; 
        echo "\n<option value='" . esc_attr($key) . "'>" . esc_html($key) . "</option>"; 
    } 
?> 
</select> 
<input class="hide-if-js" type="text" id="metakeyinput" name="metakeyinput" value="" /> 
<a href="#postcustomstuff" class="hide-if-no-js" onclick="jQuery('#metakeyinput, #metakeyselect, #enternew, #cancelnew').toggle();return false;"> 
<span id="enternew"><?php _e('Enter new'); ?></span> 
<span id="cancelnew" class="hidden"><?php _e('Cancel'); ?></span></a> 
<?php } else { ?> 
<input type="text" id="metakeyinput" name="metakeyinput" value="" /> 
<?php } ?> 
</td> 
<td><textarea id="metavalue" name="metavalue" rows="2" cols="25"></textarea></td> 
</tr> 
 
<tr><td colspan="2"> 
<div class="submit"> 
<?php submit_button( __( 'Add Custom Field' ), '', 'addmeta', false, array( 'id' => 'newmeta-submit', 'data-wp-lists' => 'add:the-list:newmeta' ) ); ?> 
</div> 
<?php wp_nonce_field( 'add-meta', '_ajax_nonce-add-meta', false ); ?> 
</td></tr> 
</tbody> 
</table> 
<?php 
 
}