Question

I have a cakephp application, in one of my controllers, I have a function _filter_callback to be used as callback to the php function array_filter() like this:

class TestClassController extends AppController
{
     var $name = 'TestClass';

     ....

     function test_fn()
     {
         ...
         array_filter($my_array, '_filter_callback');
     }

     function _filter_callback($val)
     {
          // callback logic here...
     }
}

The problem I have is that my function _filter_callback cannot be found by array_filter in my controller because I get the following error:

Warning: array_filter() expects parameter 2 to be a valid callback, 
function '_filter_callback' not found or invalid function name

Does anybody know how I can make array_filter aware of my callback function in a cakephp application?

Answer 1

Is the function in the global scope? If not – it has to be.
If the body of the function is simple (in most cases) try to use anonymous functions as of PHP > 5.3 – http://php.net/manual/en/functions.anonymous.php

or use the create_function

http://php.net/manual/en/function.create-function.php

You can then inject this as a parameter without declaring one-use global function.

Example of filtering all elements smaller than 10:

array_filter($array, create_function('$a', 'return $a > 10;'));

EDIT:
I can see now that you are trying to call method of the object. You must specify the instance. Try this:

array_filter($my_array, array($this, '_filter_callback'));