theme development - How can I add a URL field to the attachments window?

admin管理员组

文章数量:1421009

For example...

add_action('init', 'reg_tax');
function reg_tax() {
   register_taxonomy_for_object_type('category', 'attachment');
}

Adds a "Category" input field to the media manager and attachments editor. I'd like to know if its possible to alter this function to capture a "link destination" URL instead. The URL would be executed when the image is clicked.

Also need to know how to retrieve the value for this new field.

UPDATE: Thanks to Thomas Answer below, here is my final solution...

function my_image_attachment_fields_to_edit($form_fields, $post) {  
    $form_fields["custom1"] = array(  
        "label" => __("Image Links To"),  
        "input" => "text",
        "value" => get_post_meta($post->ID, "_custom1", true)  
    );        
    return $form_fields;  
}  

function my_image_attachment_fields_to_save($post, $attachment) {    
    if( isset($attachment['custom1']) ){  
        update_post_meta($post['ID'], '_custom1', $attachment['custom1']);  
    }  
    return $post;  
}  

add_filter("attachment_fields_to_edit", "my_image_attachment_fields_to_edit", null, 2); 
add_filter("attachment_fields_to_save", "my_image_attachment_fields_to_save", null, 2); 

For example...

add_action('init', 'reg_tax');
function reg_tax() {
   register_taxonomy_for_object_type('category', 'attachment');
}

Adds a "Category" input field to the media manager and attachments editor. I'd like to know if its possible to alter this function to capture a "link destination" URL instead. The URL would be executed when the image is clicked.

Also need to know how to retrieve the value for this new field.

UPDATE: Thanks to Thomas Answer below, here is my final solution...

function my_image_attachment_fields_to_edit($form_fields, $post) {  
    $form_fields["custom1"] = array(  
        "label" => __("Image Links To"),  
        "input" => "text",
        "value" => get_post_meta($post->ID, "_custom1", true)  
    );        
    return $form_fields;  
}  

function my_image_attachment_fields_to_save($post, $attachment) {    
    if( isset($attachment['custom1']) ){  
        update_post_meta($post['ID'], '_custom1', $attachment['custom1']);  
    }  
    return $post;  
}  

add_filter("attachment_fields_to_edit", "my_image_attachment_fields_to_edit", null, 2); 
add_filter("attachment_fields_to_save", "my_image_attachment_fields_to_save", null, 2); 

• theme-development

Share Improve this question edited Oct 21, 2010 at 18:23 Scott B asked Oct 20, 2010 at 18:49 Scott BScott B 5,6961414 gold badges9494 silver badges148148 bronze badges 3

• 1 Don't "namespace" your functions with "my_". Too many people do that already. ;) – fuxia ♦ Commented Oct 22, 2010 at 2:35
• Would love to know how to use this with a radio button. Changing type doesn't do anything. – Drew Baker Commented Oct 3, 2012 at 0:39
• @scottb Instead of putting your solution in the question, you should cut it out of there and paste it into an answer and then accept that. Some people think there something seems off about accepting ones own answer, but its fine and it helps future searches (like me) to get to the real answer more quickly. – Jeff Commented Nov 11, 2015 at 19:02

Add a comment  | 

2 Answers 2

Sorted by: Reset to default 16

I use a very rough plugin to add information about the artist and a URL to media files. It needs some tweaking (and I need the time), but it works and may demonstrate how add the extra fields and how to use them in your theme:

<?php
/*
Plugin Name: Media Artist Field
Description: Adds two field to attachments – Artist and Artist URL – and adds this information to captions.
Version:     0.1
Author:      Fuxia Scholz
Created:     19.09.2010
*/
$Media_Artist = new Media_Artist(
    array (
        'artist_name' => array (
            'public' => 'artist_name'
        ,   'hidden' => '_artist_name'
        ,   'label'  => 'Fotograf (Name)'
        )
    ,   'artist_url' => array (
            'public' => 'artist_url'
        ,   'hidden' => '_artist_url'
        ,   'label'  => 'Fotograf (URL)'
        )
    )
,   'Foto: '
);
/**
 * Adds two fields for credits to any media file: name and URL.
 *
 * Based on the clear tutorial by Andy Blackwell:
 * @link http://net.tutsplus/?p=13076
 */
class Media_Artist
{
    public
        $fields = array (
            'artist_name' => array (
                'public' => 'artist_name'
            ,   'hidden' => '_artist_name'
            ,   'label'  => 'Artist Name'
            )
        ,   'artist_url' => array (
                'public' => 'artist_url'
            ,   'hidden' => '_artist_url'
            ,   'label'  => 'Artist URL'
            )
        )
        // Maybe its own field?
    ,   $caption_prefix
    ,   $br_before = TRUE;

    public function __construct(
        $fields         = array()
    ,   $caption_prefix = 'Source: '
    ,   $br_before      = TRUE
    )
    {
        $this->fields         = array_merge($this->fields, $fields);
        $this->caption_prefix = $caption_prefix;
        $this->br_before      = (bool) $br_before;

        $this->set_filter();
    }

    public function set_filter()
    {
        add_filter(
            'attachment_fields_to_edit'
        ,   array ( $this, 'add_fields' )
        ,   15
        ,   2
        );
        add_filter(
            'attachment_fields_to_save'
        ,   array ( $this, 'save_fields' )
        ,   10
        ,   2
        );
        add_filter(
            'img_caption_shortcode'
        ,   array ( $this, 'caption_filter' )
        ,   1
        ,   3
        );
    }

    public function add_fields($form_fields, $post)
    {
        foreach ( $this->fields as $field)
        {
            $form_fields[ $field['public'] ]['label'] = $field['label'];
            $form_fields[ $field['public'] ]['input'] = 'text';
            $form_fields[ $field['public'] ]['value'] = get_post_meta(
                $post->ID
            ,   $field['hidden']
            ,   TRUE
            );
        }
        return $form_fields;
    }

    public function save_fields($post, $attachment)
    {
        foreach ( $this->fields as $field)
        {
            if ( isset ( $attachment[ $field['public'] ]) )
            {
                update_post_meta(
                    $post['ID']
                ,   $field['hidden']
                ,   $attachment[ $field['public'] ]
                );
            }
        }

        return $post;
    }

    public function caption_filter($empty, $attr, $content = '')
    {
        /* Typical input:
         * [caption id="attachment_525" align="aligncenter"
         * width="300" caption="The caption."]
         * <a href="http://example/2008/images-test/albeo-screengrab/"
         * rel="attachment wp-att-525"><img
         * src="http://example/uploads/2010/08/albeo-screengrab4.jpg?w=300"
         * alt="" title="albeo-screengrab" width="300" height="276"
         * class="size-medium wp-image-525" /></a>[/caption]
         */
        extract(
            shortcode_atts(
                array (
                    'id'        => ''
                ,   'align'     => 'alignnone'
                ,   'width'     => ''
                ,   'caption'   => ''
                ,   'nocredits' => '0'
                )
            ,   $attr
            )
        );

        // Let WP handle these cases.
        if ( empty ($id ) or 1 == $nocredits )
        {
            return '';
        }

        if ( 1 > (int) $width || empty ( $caption ) )
        {
            return $content;
        }

        if ( ! empty ( $id ) )
        {
            // Example: attachment_525
            $html_id     = 'id="' . esc_attr($id) . '" ';
            $tmp         = explode('_', $id);
            $id          = end($tmp);

            $sub_caption = '';
            $artist_name = get_post_meta($id, $this->fields['artist_name']['hidden'], TRUE);
            $artist_url  = get_post_meta($id, $this->fields['artist_url']['hidden'], TRUE);

            // Okay, at least one value.
            if ( '' != $artist_name . $artist_url )
            {
                $sub_caption .= $this->br_before ? '<br />' : '';
                $sub_caption .= '<span class="media-artist">' . $this->caption_prefix;

                // No name given. We use the shortened URL.
                if ( '' == $artist_name )
                {
                    $sub_caption .= '<a rel="author" href="'
                        . $artist_url . '">'
                        . $this->short_url($artist_url)
                        . '</a>';
                } // We have just the name.
                elseif ( '' == $artist_url )
                {
                    $sub_caption .= $artist_name;
                } // We have both.
                else
                {
                    $sub_caption .= '<a rel="author" href="'
                        . $artist_url . '">'
                        . $artist_name
                        . '</a>';
                }

                $sub_caption .= '</span>';
            }

            $caption .= $sub_caption;
        }

        return '<div ' . $html_id . 'class="wp-caption ' . esc_attr($align)
        . '" style="width: ' . (10 + (int) $width) . 'px">'
        . do_shortcode( $content ) . '<p class="wp-caption-text">'
        . $caption . '</p></div>';
    }

    public function short_url($url, $max_length=20)
    {
        $real_length = mb_strlen($url, 'UTF-8');

        if ( $real_length <= $max_length )
        {
            return $url;
        }

        $keep = round( $max_length / 2 ) - 1;

        return mb_substr($url, 0, $keep, 'UTF-8') . '…'
            . mb_substr($url, -$keep, $real_length, 'UTF-8');
    }
    # @todo uninstall
}

Responding to Drew's question in the comments, you can customize the HTML for the field by setting the input to a new string, and then adding that same string as a key to the $form_fields array.

By default, WordPress will only accept text and textarea for the input type. Anything else will have to be defined in a custom way as below. I haven't tried actually persisting form fields this way so in order to make another input type, like a radio button, might take a little extra finesse.

add_filter( 'attachment_fields_to_edit', 'change_fields', 10, 2 );
function change_fields( $form_fields, $post ) {

    $form_fields["some_new_field"] = array(  
            "label" => __("Type something"),
            "input" => "arbitrary_value",
            "value" => get_post_meta($post->ID, "some_new_field", true),
            "arbitrary_value" => "hello world!"
        );
}

本文标签： theme developmentHow can I add a URL field to the attachments window