Add error message when assert is false

[vonglasow]

Take an example

// The User object.
class User {

    const DISCONNECTED = 0;
    const CONNECTED    = 1;

    public $group      = 'customer';
    public $points     = 42;
    protected $_status = 0;

    public function getStatus ( ) {

        return $this->_status;
    }
}

$ruler = new Hoa\Ruler\Ruler();

// New rule.
$rule  = 'logged(user) and group in ["customer", "guest"] and points > 30';

// New context.
$context         = new Hoa\Ruler\Context();
$context['user'] = function ( ) use ( $context ) {

    $user              = new User();
    $context['group']  = $user->group;
    $context['points'] = $user->points;

    return $user;
};

// We add the logged() operator.
$ruler->getDefaultAsserter()->setOperator('logged', function ( User $user ) {

    return $user::CONNECTED === $user->getStatus();
});

// Finally, we assert the rule.
var_dump(
    $ruler->assert($rule, $context)
);

/**
 * Will output:
 *     bool(false)
 */

Ok so we have here a rule not respected, but why this rule doesn't passed is it because we have the user logout or because them points is <= 30
It could be useful to identify the reason of breaking rules. But all rules depends on operator so I think the operator could provide a property with error message when the result of validation is false and aggregate in ruler to got it.

To continue the example above

var_dump(
    $ruler->getErrorMessages();
);
/**
 * Will output:
 *     array(
 *         'User is not logged'
 *     )
 */

What do you think ?

[Hywan]

Huge 👍 on this one!

[simkimsia]

👍

[gael-wogenstahl]

+1

[1e1]

It seems compex to explain what is wrong if the function has more parameter.
What's happens with:
$rule = 'logged(user, channel) and group in ["customer", "guest"] and points > 30';

var_dump(
    $ruler->getErrorMessages();
);
/**
 * Will output:
 *     array(
 *         'User "Object" is not logged on channel 2'
 *     )
 */

?

Perhaps, something like SQL explain should be more generic, even the message wil be more technical.

I see a response like:

var_dump(
    $ruler->explain();
);
/**
 * Will output:
 * logged(user, channel) and group in ["customer", "guest"] and points > 30' = false
 * |  logged(user, channel) = false
 * |    user = { ..json_encode.. }
 * |    channel = 2 // is json_encoded
 * |  BREAK
 */

[1e1]

And a complete explaination:

var_dump(
    $ruler->explain();
);
/**
 * Will output:
 * logged(user, channel) and group in ["customer", "guest"] and points > 30' = true
 * | logged(user, channel) and group in ["customer", "guest"] = true
 * |  |  logged(user, channel) = true
 * |  |  |  user = { ..json_encode.. }
 * |  |  |  channel = 2
 * |  |  group in ["customer", "guest"] = true
 * |  |  |  group = "customer"
 * | points > 30'  = true
 * |  |  points = 42
 */

[1e1]

@vonglasow
I wonder how var_dump($context) and closure_dump() could solve this issue.
As you use a closure to define User context if you change:
$rule = 'logged(user) and group in ["customer", "guest"] and points > 30';
to
$rule = 'group in ["customer", "guest"] and points > 30 and logged(user)';
I will catch an exception because group and points are setted when you get user.

Perhaps using a Closure to define the context is not a good practice?

[Hywan]

@1e1 I like your proposal in #41 (comment), having the tree/AST view of the rule with associated error is a good __toString, if we go in this direction.

[vonglasow]

@1e1
For now we have this kind of output

array(1) {
  ["f"]=>
  array(1) {
    [0]=>
    object(Hoa\Ruler\Model\Bag\Scalar)#251 (1) {
      ["_value":protected]=>
      bool(false)
    }
  }
}

But we can improve it. I will try to make a test with your exemple to show you what is done yet. And if you have any idea to make this AST let me know we can work on it together.
@Hywan I am OK also for an AST, we talk together about an API to manage errors. What do you see for there next step ?

[Hywan]

@vonglasow Not sure. I don't know what the user needs exactly here. It is not defined. In what case are we likely to use the errors API? What do we expect? What information do we need?