actions - How to do_action and get a return value?

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So there is the following scenario.

I add an action to clean logs from the database:

add_action( 'myplugin_clean_logs', array( 'MyPlugin_Logs', 'clean_logs' ) );

Now I want to run this action periodically:

wp_schedule_event( current_time( 'timestamp' ), 'daily', 'myplugin_clean_logs' );

and execute it manually:

do_action( 'myplugin_clean_logs' );

The method MyPlugin_Logs::clean_logs returns the count of affected rows or false if something went the other direction.

Now I want to display the number of rows that have been deleted. I would imagine something like this:

$affected_rows = do_action( 'myplugin_clean_logs' );
echo $affected_rows . ' entries have been deleted.';

But as do_action will not return any value, I have no idea how to get the return value.

Should I execute the method directly on a manual run, but use the action on schedule events?

So there is the following scenario.

I add an action to clean logs from the database:

add_action( 'myplugin_clean_logs', array( 'MyPlugin_Logs', 'clean_logs' ) );

Now I want to run this action periodically:

wp_schedule_event( current_time( 'timestamp' ), 'daily', 'myplugin_clean_logs' );

and execute it manually:

do_action( 'myplugin_clean_logs' );

The method MyPlugin_Logs::clean_logs returns the count of affected rows or false if something went the other direction.

Now I want to display the number of rows that have been deleted. I would imagine something like this:

$affected_rows = do_action( 'myplugin_clean_logs' );
echo $affected_rows . ' entries have been deleted.';

But as do_action will not return any value, I have no idea how to get the return value.

Should I execute the method directly on a manual run, but use the action on schedule events?

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Share Improve this question edited Apr 22, 2016 at 7:06 Aley asked Apr 21, 2016 at 16:47 AleyAley 38111 gold badge33 silver badges88 bronze badges 1

• 1 You don't want to be echo'ing anything on a scheduled event, so yes, I would execute the method directly on a manual run (I'm assuming the administrator would trigger this, and you want to show them the output). – Tim Malone Commented Apr 21, 2016 at 22:55

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3 Answers 3

Sorted by: Reset to default 16

The cool thing is a filter is the same as an action, only it returns a value, so just set it up as a filter instead:

add_filter( 'myplugin_clean_logs', array( 'MyPlugin_Logs', 'clean_logs' ) );

Then something like:

$affected_rows = '';
$affected_rows = apply_filters( 'myplugin_clean_logs', $affected_rows );

should pass $affected_rows to clean_logs() (and whatever other functions you may have hooked to myplugin_clean_logs) and assign the return value back to $affected_rows.

This is a very old question but to answer the original question "How to do_action and get a return value?" for anyone looking you can do this using output buffering.

ob_start();
    do_action( 'myplugin_clean_logs' );
$action_data = ob_get_clean();

This way you can store the do_action content in a variable.

Never used this function and haven't tested this, but might it work? do_action_ref_array().

function myplugin_clean_logs_fn() {
    $args = array(
        'param1'        => 'val1',
        'param2'        => 'val2',
        'affected_rows' => 0,
    );
    do_action_ref_array( 'myplugin_clean_logs', &$args );
    return $args['affected_rows'];
}

// CALL IT
$affected_rows = my_plugin_clean_logs();
echo $affected_rows .' entr'. ($args['affected_rows']*1===1?'y':'ies') .' deleted.';

// SCHEDULE IT
add_action('myplugin_clean_logs_call_fn', 'myplugin_clean_logs_fn');
wp_schedule_event( current_time( 'timestamp' ), 'daily', 'myplugin_clean_logs_call_fn' );

// A SAMPLE FILTER
add_action('myplugin_clean_logs', function($args) {
    // Cleaning process
    // For each log affected, increment $args['affected_rows'] accordingly
}, 10, 3);

If that doesn't work, why not just filter the thing like Caspar suggested? I mean, that is the purpose of a filter, and in this case the number of affected rows is the thing being filtered. (I miss the old MortCore. Anyone remember how it handled return values, pass-by-reference, and arguments with just a single three parameter function?)

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