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We upload a lot of photos to WordPress. We do not use them all though. The unused ones remain "attached" to the post it's not in which makes it hard to go back and delete it.

I've build 2 arrays. One array contains all of the images from the post content ($postImages). The other array contains all of the images WordPress database have attached to the post ($mediaImages).

I'm trying to identify which images appear in the database, but not in the post. This way I can detach the image from within the database.

I'm using array_diff to compare the two arrays, however it's not showing the odd man out. It appears to be showing the matches.

Here's my arrays:

Call this one $postImages:

var_dump($postImages);

array(3) {
  [2]=>
  string(64) "http://mywebsite.com/wp-content/uploads/2013/11/photoblog1.jpg"
  [0]=>
  string(64) "http://mywebsite.com/wp-content/uploads/2013/11/photoblog2.jpg"
  [1]=>
  string(64) "http://mywebsite.com/wp-content/uploads/2013/11/photoblog3.jpg"
}

And $mediaImages:

var_dump($mediaImages);

array(4) {
  [1]=>
  array(1) {
    [0]=>
    string(64) "http://mywebsite.com/wp-content/uploads/2013/11/photoblog1.jpg"
  }
  [2]=>
  array(1) {
    [0]=>
    string(64) "http://mywebsite.com/wp-content/uploads/2013/11/photoblog2.jpg"
  }
  [0]=>
  array(1) {
    [0]=>
    string(64) "http://mywebsite.com/wp-content/uploads/2013/11/photoblog3.jpg"
  }
  [3]=>
  array(1) {
    [0]=>
    string(62) "http://mywebsite.com/wp-content/uploads/2013/12/IMG_0069.jpg"
  }
}

Here is the output:

$matches = array_diff($postImages, $mediaImages);
print_r($matches);

Array
(
    [2] => http://mywebsite.com/wp-content/uploads/2013/11/photoblog1.jpg
    [0] => http://mywebsite.com/wp-content/uploads/2013/11/photoblog2.jpg
    [1] => http://mywebsite.com/wp-content/uploads/2013/11/photoblog3.jpg
)

Expected output:

Array
(
    [0] => http://mywebsite.com/wp-content/uploads/2013/12/IMG_0069.jpg
)
share|improve this question
3  
$mediaImages is an array of arrays of strings, while $postimages is simply an array of strings. You can't diff arrays that have inherrently different structures and expect to get valid results. –  Marc B Dec 29 '13 at 20:37
 
Good catch. I missed that, must have been staring too long. Is there a way to condense $mediaImages into the same format as $postImages? –  Pat Dec 29 '13 at 20:38
2  
array_map/foreach over mediaimages and build the same structure as in $postimages. –  Marc B Dec 29 '13 at 20:39
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1 Answer

up vote 1 down vote accepted

As Marc B pointed out in the comments, $mediaImages is an array of arrays of strings, while $postimages is just an array of strings.

You can use array_map() with a custom callback to create the $mediaImages array:

$mediaImages = array_map(function($item) { 
    return $item[0]; 
}, $mediaImages);

Also, note that you have the parameters for array_diff() backwards. The correct order is:

array_diff($arrayToCompareFrom , $arrayToCompareAgainst);

So to compare $postImages against $mediaImages, you'd need:

$matches = array_diff($mediaImages, $postImages);
print_r($matches);

Demo.

share|improve this answer
 
The demo helped me visualize it. Worked great. –  Pat Dec 29 '13 at 20:50
 
@Pat: Glad to have been of help! :) –  Amal Murali Dec 29 '13 at 20:51
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