filter.md

Using a rule to filter a target

This guide will show you how to filter any kind of target using a simple language.

Here is a summary of what you will have to do:

• instantiate the RulerZ engine and be sure to include an instance of \RulerZ\Target\Native\Native to the compilation targets ;
• write a rule ;
• filter your target.

Context

In the following examples, we'll define rules to filter this collection:

$users = [
    ['pseudo' => 'Joe',   'gender' => 'M', 'points' => 40],
    ['pseudo' => 'Moe',   'gender' => 'M', 'points' => 20],
    ['pseudo' => 'Alice', 'gender' => 'F', 'points' => 60],
];

Note: RulerZ will work the same way, whether you want to filter a collection of arrays or a collection of objects.

Filter your target

Let's say that we want to retrieve the female players having at least 30 points. The rule describing these constraints would look like this:

$rule  = 'gender = :gender and points > :min_points';

Where :gender and :min_points are parameters that we'll need to define as an array:

$parameters = [
    'min_points' => 30,
    'gender'     => 'F',
];

Once the rule is written and the parameters are defined, only the easiest part remains: filtering the target.

var_dump(
    iterator_to_array(
        $rulerz->filter($players, $rule, $parameters) // the parameters can be omitted if empty
    )
);

// will return:
/*
array(1) {
  [0]=>
  array(3) {
    ["pseudo"]=>
    string(5) "Alice"
    ["gender"]=>
    string(1) "F"
    ["points"]=>
    int(60)
  }
}
*/

Yup, it's that easy.

That was it!

Return to the index to explore the other possibilities of the library