Wie kann ich den Alt-Text eines Bildanhangs abrufen?

Question

Wie kann ich den Alt-Text eines Bildanhangs abrufen?

33

64415 2010-08-30

Ich verwendeeine Anhang.php-Datei,umgroße Versionen von Bildern anzuzeigen,auf die an anderer Stellegeklickt wurde. Ichmöchte den Bild-Alternativtext als Beschriftungmit Javascript unter das Bild ziehen,aber der Alternativtextistnichtenthalten,wenn wp_get_attachment_image_src () verwendet wird. Ichglaubenicht,dass WPeine Funktion zum Abrufen hat,alsobraucheichmeine eigene. Um diese Funktion zu schreiben,mussich wissen ... Woist der Alternativtextfürein Bildgespeichert?

Meine Anhangsseite verwendet wp_get_attachment_image_src(),der den Alternativtextnichtenthält.

 <div class = "entry">
<?php 
if ( wp_attachment_is_image( $post->id ) ) : 
    $att_image = wp_get_attachment_image_src( $post->id, "large");?>

    <a href="<?php echo wp_get_attachment_url($post->id); ?>" 
        title="<?php the_title(); ?>" 
        rel="attachment">
    <img class="attached_img" 
        src="<?php echo $att_image[0];?>" 
        width="<?php echo $att_image[1];?>" 
        height="<?php echo $att_image[2];?>"  
        class="attachment-medium" 
        alt="<?php $post->post_excerpt; ?>" />
    </a> 
} <?php endif;?>
</div>

Dies zeigt:

 <div class = "entry">
    <a href="http://www.example.com/wp-content/uploads/2010/07/photo_namejpg" 
       title="My_Photo_Title" 
       rel="attachment">
       <img class="attached_img" 
            src="http://www.example.com/wp-content/uploads/2010/07/photo_name_and_size.jpg" 
            width="393" 
            height="500"  
            class="attachment-medium" 
            alt="" />
    </a>
</div>

Miristbekannt,dass der $post->post_excerptim obigen Code aufgerufen wird,aberichbin nicht sicher,durch waserersetzt werden soll,um das alt-Attribut des Bildes zuerhalten.

I am using an attachment.php file to show large versions of images that have been clicked on elsewhere. I'd like to pull the image alt text as a caption under the image with javascript, but the alt text isn't included when when wp_get_attachment_image_src() is used. I don't think WP has a function to retrieve it, so I need my own. To write that function I need to know...Where is the alt text for an image stored?

My attachment page uses wp_get_attachment_image_src(), which doesn't include the alt text.

<div class = "entry">
<?php 
if ( wp_attachment_is_image( $post->id ) ) : 
    $att_image = wp_get_attachment_image_src( $post->id, "large");?>

    <a href="<?php echo wp_get_attachment_url($post->id); ?>" 
        title="<?php the_title(); ?>" 
        rel="attachment">
    <img class="attached_img" 
        src="<?php echo $att_image[0];?>" 
        width="<?php echo $att_image[1];?>" 
        height="<?php echo $att_image[2];?>"  
        class="attachment-medium" 
        alt="<?php $post->post_excerpt; ?>" />
    </a> 
} <?php endif;?>
</div>

This shows:

<div class = "entry">
    <a href="http://www.example.com/wp-content/uploads/2010/07/photo_namejpg" 
       title="My_Photo_Title" 
       rel="attachment">
       <img class="attached_img" 
            src="http://www.example.com/wp-content/uploads/2010/07/photo_name_and_size.jpg" 
            width="393" 
            height="500"  
            class="attachment-medium" 
            alt="" />
    </a>
</div>

I'm aware that the $post->post_excerpt is being called in the above code, but I am not sure what to replace it with to get the image's alt attribute.

5 Antworten

Stimmen

Tom Auger · Answer 1 · 2015-04-23

5

2015-04-23

Betrachten Sie wp_prepare_attachment_for_js( $attachment ),wobei $attachment das WP_Post-Objekt des Anhangs selbstist.

Diesisteine Art "Küchenspüle" -Funktion,bietet jedocheinen sehr schönen Hashmit einer Menge Metadaten,einschließlich 'alt':

 $response = array(
        'id'          => $attachment->ID,
        'title'       => $attachment->post_title,
        'filename'    => wp_basename( $attachment->guid ),
        'url'         => $attachment_url,
        'link'        => get_attachment_link( $attachment->ID ),
        'alt'         => get_post_meta( $attachment->ID, '_wp_attachment_image_alt', true ),
        'author'      => $attachment->post_author,
        'description' => $attachment->post_content,
        'caption'     => $attachment->post_excerpt,
        'name'        => $attachment->post_name,
        'status'      => $attachment->post_status,
        'uploadedTo'  => $attachment->post_parent,
        'date'        => strtotime( $attachment->post_date_gmt ) * 1000,
        'modified'    => strtotime( $attachment->post_modified_gmt ) * 1000,
        'menuOrder'   => $attachment->menu_order,
        'mime'        => $attachment->post_mime_type,
        'type'        => $type,
        'subtype'     => $subtype,
        'icon'        => wp_mime_type_icon( $attachment->ID ),
        'dateFormatted' => mysql2date( get_option('date_format'), $attachment->post_date ),
        'nonces'      => array(
            'update' => false,
            'delete' => false,
            'edit'   => false
        ),
        'editLink'   => false,
        'meta'       => false,
    );

Diesistbesondersnützlich (wie der Name schon sagt),um das Meta des Anhangsbilds über wp_send_ajax() aneine wp.media-Ansicht zu senden. Diesbedeutetjedochnicht,dass Sieesnicht verwenden könnenfür andere Zwecke.

Ichmages,vom Post-Meta-Feld _wp_attachment_image_alt weg zu abstrahieren,falls sich die Methode zum Abrufen des Alternativtextesjemals ändert (unwahrscheinlich,aber denkbar).

Ich habejedoch das Gefühl,dasseseinen Fallfüreine wp_get_attachment_image_alt() -Methodegibt.

Consider looking at wp_prepare_attachment_for_js( $attachment ), where $attachment is the WP_Post object of the attachment itself.

This is a bit of a "kitchen sink" function, but it does provide a very nice hash with a ton of metadata, including 'alt':

$response = array(
        'id'          => $attachment->ID,
        'title'       => $attachment->post_title,
        'filename'    => wp_basename( $attachment->guid ),
        'url'         => $attachment_url,
        'link'        => get_attachment_link( $attachment->ID ),
        'alt'         => get_post_meta( $attachment->ID, '_wp_attachment_image_alt', true ),
        'author'      => $attachment->post_author,
        'description' => $attachment->post_content,
        'caption'     => $attachment->post_excerpt,
        'name'        => $attachment->post_name,
        'status'      => $attachment->post_status,
        'uploadedTo'  => $attachment->post_parent,
        'date'        => strtotime( $attachment->post_date_gmt ) * 1000,
        'modified'    => strtotime( $attachment->post_modified_gmt ) * 1000,
        'menuOrder'   => $attachment->menu_order,
        'mime'        => $attachment->post_mime_type,
        'type'        => $type,
        'subtype'     => $subtype,
        'icon'        => wp_mime_type_icon( $attachment->ID ),
        'dateFormatted' => mysql2date( get_option('date_format'), $attachment->post_date ),
        'nonces'      => array(
            'update' => false,
            'delete' => false,
            'edit'   => false
        ),
        'editLink'   => false,
        'meta'       => false,
    );

This is particularly useful (as the name implies), for sending the attachment image meta to a wp.media View via wp_send_ajax(), but that doesn't mean you couldn't use it for other purposes.

I like abstracting away from the _wp_attachment_image_alt post meta field, in case the method to retrieve the alt text ever changes (unlikely, but conceivable).

I do feel that there's a case for a wp_get_attachment_image_alt() method however.

Genau das,wonachichgesucht habe.Hatjemandeine Vorstellung von seiner Leistung?Bei so vielen verschiedenen Werten werden ...ichfragemich ...

Exactly what i was looking for. Does anyone have an idea of its performance? With so many different values it retrieves... I wonder...
- 0
- 2015-07-16
- Larzan
@Larzan Ich würdemir keine Sorgen um die Leistungmachen -es sei denn,Sieerhalten Hunderte von Bilddatengleichzeitig ...

@Larzan I wouldn't worry about performance - unless you're getting hundreds of images data at the same time...
- 0
- 2015-07-17
- Tom Auger

GUI Junkie · Answer 2 · 2015-02-11

4

2015-02-11

Mikes Antwortistnatürlich richtig,aber $alt_text = get_post_meta($post->ID, '_wp_attachment_image_alt', true);gibt möglicherweiseeine leere Zeichenfolge zurück.

wp_get_attachment_image Erhältjedochimmereinen alt_text.

Das Wordpress-Team wendet zuerst denfolgenden Trick an,indemesnachpost_except sucht und dann den Titelerhält.

 if(empty($alt_text)) // If not, Use the Caption
{
    $attachment = get_post($post->ID);
    $alt_text = trim(strip_tags( $attachment->post_excerpt ));
}
if(empty($alt_text)) // Finally, use the title
{ 
    $attachment = get_post($post->ID);
    $alt_text = trim(strip_tags( $attachment->post_title )); 
}

Mike's answer is correct, of course, but $alt_text = get_post_meta($post->ID, '_wp_attachment_image_alt', true); may return an empty string.

wp_get_attachment_image, however, does always get an alt_text.

The Wordpress team applies the following trick, first, checking for the post_except, then obtaining the title.

if(empty($alt_text)) // If not, Use the Caption
{
    $attachment = get_post($post->ID);
    $alt_text = trim(strip_tags( $attachment->post_excerpt ));
}
if(empty($alt_text)) // Finally, use the title
{ 
    $attachment = get_post($post->ID);
    $alt_text = trim(strip_tags( $attachment->post_title )); 
}

chilljul · Answer 3 · 2011-12-26

2

2011-12-26

Ich habe herausgefunden,dass der Alt-Textfür Anhängein einembenutzerdefinierten Metanamens "_wp_attachment_image_alt"

gespeichert wurde

Mit der ID des Anhangs konnteich den Alternativtextmit folgendem Code abrufen:

 <?php echo get_post_meta($attachment_id, '_wp_attachment_image_alt', true) ?>

I found out that the Alt text for attachments was stored on a custom meta called "_wp_attachment_image_alt"

So having the attachment's Id, I was able to get the alt text with this code:

<?php echo get_post_meta($attachment_id, '_wp_attachment_image_alt', true) ?>

DevTurtle · Answer 4 · 2017-04-28

0

2017-04-28

Wenn Sie WP_Customize_Media_Control () verwenden,gibt get_theme_mod () die Post-ID zurück. Wenn Siejedoch dasneue WP_Customize_Image_Control () verwenden,gibt get_theme_mod () die Bild-URL zurück,von derich den Alternativtexterhalten konnteVerwenden von WP_Customize_Image_Control ()

So konnteichesmachen.Hoffe das hilftjemandem da draußen

 // This is getting the image / url
$feature1 = get_theme_mod('feature_image_1');

// This is getting the post id
$feature1_id = attachment_url_to_postid($feature1);

// This is getting the alt text from the image that is set in the media area
$image1_alt = get_post_meta( $feature1_id, '_wp_attachment_image_alt', true );

Markup

 <a href="<?php echo $feature1_url; ?>"><img class="img-responsive center-block" src="<?php echo $feature1; ?>" alt="<?php echo $image1_alt; ?>"></a>

If you are using WP_Customize_Media_Control() your get_theme_mod() will return the post id but if you are using the new WP_Customize_Image_Control() the get_theme_mod() will return the image url this was how I was able to get the alt text from using the WP_Customize_Image_Control()

Here is how I was able to do it. Hope this helps someone out there

// This is getting the image / url
$feature1 = get_theme_mod('feature_image_1');

// This is getting the post id
$feature1_id = attachment_url_to_postid($feature1);

// This is getting the alt text from the image that is set in the media area
$image1_alt = get_post_meta( $feature1_id, '_wp_attachment_image_alt', true );

Markup

<a href="<?php echo $feature1_url; ?>"><img class="img-responsive center-block" src="<?php echo $feature1; ?>" alt="<?php echo $image1_alt; ?>"></a>

Uriahs Victor · Answer 5 · 2017-08-10

0

2017-08-10

Um Mikes Antwort zuergänzen,könnte diesjemandnützlichfinden.Möglicherweisemüssen Sie die spezifische ID des Anhangs abrufen,indem Sie die Post-ID an get_post_thumbnail_id übergeben. Beispiel:

   $the_img = wp_get_attachment_image( get_post_thumbnail_id( get_the_ID() ) );

To add to Mike's answer someone might find this useful. You might need to get the specific ID of the attachment, so you can do so by passing the Post ID to get_post_thumbnail_id example:

  $the_img = wp_get_attachment_image( get_post_thumbnail_id( get_the_ID() ) );