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I'm adding a filter for a WordPress query in a widget. I'm adding as following:

function filter_where( $where = '' ) {

}
add_filter( 'posts_where', 'filter_where' );
$query = new WP_Query( $args );
remove_filter( 'posts_where', 'filter_where' );

It works fine, but if I use the same widget more than 1 times then I get the fatal error that the same filter cannot be re-declared. How can I use the filter so that the same widget can be used multiple times?

This is the exact error I get:

Fatal error: Cannot redeclare filter_where() (previously declared in xxx.php:70)

Thanks.

  • Can you be more specific? What does the Fatal error say. It sounds like the function thinks it's being defined twice? Maybe a if ( !function_exists('filter_where')) {} wrapper would do the trick. – Eric Holmes Jan 21 '14 at 21:14
  • @EricHolmes I have updated the question, please check. – enam Jan 21 '14 at 21:27
  • It's looking like a namespace issue. Try changing it to enam_filter_where in both your add/remove filter statements, and the function definition - still get the error? A plugin you have may have the same function name. – Eric Holmes Jan 21 '14 at 21:29
1

Your code should look something like this:

class my_Widget extends WP_Widget {

...

function filter_where( $where = '' ) {
    ...
}

function widget( $options ) {
    ...
    add_filter( 'posts_where', array( $this, 'filter_where' ) );
    $query = new WP_Query( $args );
    remove_filter( 'posts_where', array( $this, 'filter_where' ) );
}
}

This will keep the function within your class, access it at a class level, and avoid any namespace issues.

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You must be defining your callback function inside a function that is reused by the widget system-- my guess is inside the widget method.

Define the callback outside the widget itself, and only apply (apply_filter) inside the widget.

In other words, add your callback as class method, and add it something like this:

add_filter('posts_where', array($this,'filter_where'));

You should be able to remove it with a similar syntax.

Without seeing your code in context that is the best I've got.

  • Thanks for the answer. Yes, I'm using it in the widget method, as you can see above that I added it just before the WP_Query and removed it after that. Could you please give an example of adding and removing it outside the widget method. – enam Jan 21 '14 at 21:28
  • @enam : see the edit. – s_ha_dum Jan 21 '14 at 21:45

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