Fix ActiveRelationTrait.php for compatibility 7.4

[indrig]

Fix for PHP 7.4

Trying to access array offset on value of type null
When $model is null on Php 7.4:
if (($value = $model[$attribute]) !== null)

/var/www/builds/cms/3.6.0/vendor/yiisoft/yii2/db/ActiveRelationTrait.php line 526

#0 /var/www/builds/cms/3.6.0/vendor/yiisoft/yii2/db/ActiveRelationTrait.php(526): yii\base\ErrorHandler->handleError()
#1 /var/www/builds/cms/3.6.0/vendor/yiisoft/yii2/db/ActiveRelationTrait.php(246): yii\db\ActiveQuery->filterByModels()
#2 /var/www/builds/cms/3.6.0/vendor/yiisoft/yii2/db/ActiveQueryTrait.php(151): yii\db\ActiveQuery->populateRelation()
#3 /var/www/builds/cms/3.6.0/vendor/yiisoft/yii2/db/ActiveQuery.php(224): yii\db\ActiveQuery->findWith()

Q	A
Is bugfix?	✔️
New feature?	❌
Breaks BC?	❌
Tests pass?	❌
Fixed issues	comma-separated list of tickets # fixed by the PR, if any

[yii-bot]

Thank you for putting effort in the improvement of the Yii framework.
We have reviewed your pull request.

In order for the framework and your solution to remain stable in the future, we have a unit test requirement in place. Therefore we can only accept your pull request if it is covered by unit tests.

Could you add these please?

Thanks!

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This is an automated comment, triggered by adding the label pr:request for unit tests.

[samdark]

Looking at the code I don't see anything that would fail on PHP 7 but won't fail on PHP 5. Are you sure it's PHP 7 specific?

[Ximich]

@samdark, yes, I can confirm it's php 7.4 incompatible change: https://www.php.net/manual/en/migration74.incompatible.php

Array-style access of non-arrays
Trying to use values of type null, bool, int, float or resource as an array (such as $null["key"]) will now generate a notice.

• see also: PHP 7.4 ActiveRelationTrait bug. Trying to access array offset on value of type null  #17914

Please, merge this PR.

[Ximich]

Do I need create another PR or you can merge this one?

[rob006]

@Ximich How can you get null in $models?

[Ximich]

@rob006, in relation with via, where relation attribute has null value.

    public function getSomething()
    {
        return $this->hasOne(Something::class, ['id' => 'something_id'])->via('viaAnotherModel');
    }

Example:

class Thing extends ActiveRecord
{
    public function getSomething()
    {
        return $this->hasOne(Something::class, ['id' => 'something_id'])->via('viaAnotherModel');
    }
}

$thing = new Thing;
$thing->id = 1;
$thing->something_id = null;
$thing->save();

Thing::find()->where(['id' => 1])->one(); // throw this exception

This code works fine in php 7.3.

[Ximich]

populateRelation() method in ActiveRelationTrait return $viaModels with null value in this case here: https://github.com/yiisoft/yii2/blob/master/framework/db/ActiveRelationTrait.php#L245

[rob006]

Shouldn't we remove these nulls from $models before calling filterByModels()? IMO it looks weird that this method needs to handle nulls, while it obviously expecting models.

[Ximich]

I don't know where's right place to filter null models. @samdark, what do you think: should we filter null $models in populateRelation() method or check it in filterByModels()?

[samdark]

Filtering sounds like a right thing to do.

[yii-bot]

It has been 2 or more weeks with no response on our request for more information.
In order for our issue tracker to be effective, we are closing this issue.

If you want it to be reopened again, feel free to supply us with the requested information.

Thanks!

This is an automated comment, triggered by adding the label expired.