How to use query filter in WordPress

query filter

Some queries are made before the plugins have been loaded, and thus cannot be filtered with this method.

To use query filter, first, you have to register it using add_filter. You can write this code into functions.php of your activated theme or in a custom WordPress Plugin.

At WePlugins, we always prefer to create a custom WordPress Plugin while using hooks so nothing breaks when you update your WordPress Theme in the future.

In the below live example, we have defined a function weplugins_modify_query_defaults which takes 1 parameter, and we registered it using add_filter. The first parameter query is the name of the hook. The second parameter weplugins_modify_query_defaults is the name of the function that needs to be called. The third parameter is the priority of calling the hook if the same hook is used multiple times, and the last parameter is the number of arguments (if any) to be passed in the registered function.

Sometimes, you have to remove a registered hook, so you can use remove_filter to remove query filter.

Example 1: Basic Query Filter

Below is an example of how you can use this hook.

    function weplugins_modify_query_defaults($query) { 
        // Update the $query variable according to your website requirements and return this variable. 
        // You can modify the $query variable conditionally too if you want.
        return $query; 
    }
    // add the filter
    add_filter( "query", "weplugins_modify_query_defaults", 10, 1 );
    

Example 2: Removing a Hook Callback

To remove a hook callback, use the example below.

    remove_filter( "query", "weplugins_modify_query_defaults", 10, 1 );
    

Please make sure to provide the same callback function name, priority, and number of arguments while removing the hook callback.

Example 3: Conditional Query Modification

Here’s how you might modify the query conditionally.

    function weplugins_modify_query_conditionally($query) { 
        if ( some_condition() ) {
            // Modify $query based on condition
        }
        return $query; 
    }
    add_filter( "query", "weplugins_modify_query_conditionally", 10, 1 );