json and activerecord attribute

[dizews]

Hello.

I have an attribute which contain a json string. I want to get an element of a json as a property of object.

example: $model->position->lng where $model->position is a json string.

It is a good idea to describe this example (or similar) in docs.

[Ragazzo]

can be resolved by afterFind i think and creating needed object, or not asking and just pointing to add this to docs?

[dizews]

@Ragazzo it is good for find but I want to get an object after load too.

[qiangxue]

Using afterFind is not a good idea because you would have to worry about what if you modify this attribute.

It's better to add a getter: getPositionObject() which returns the object representation of position. You can develop the getter and/or setter in a way such that it will allow you to modify part of the object.

[dizews]

@qiangxue by your logic I will get bidirectional changes. I can't imagine how to get away from rewrite attribute value (save, asArray...)

[Ragazzo]

@qiangxue why one should be worry if it is called after find? is not it the case like for before / after methods?

@dizews in your case it should not be AR, it can be simple object, saving will require saving primary model and in beforeSave setting needed attribute according to the created object value.

[lynicidn]

return [
            'load' => [
                'class' => \yii\behaviors\AttributeBehavior::className(),
                'attributes' => [
                    self::EVENT_AFTER_FIND => 'jsonstring',
                    self::EVENT_AFTER_UPDATE => 'jsonstring',
                    self::EVENT_AFTER_INSERT => 'jsonstring',
                    self::EVENT_INIT => 'jsonstring',
                    ...
                    ]
                'value' => function ($event) {
                        if (is_string($this->jsonstring)) {
                            $this->jsonstring = new SubModel(['attributes' => json_decode($this->jsonstring)]);
                        }
                    }
            ],
            'unload' => [
                'class' => \yii\behaviors\AttributeBehavior::className(),
                'attributes' =>[
                    ...
                ],
                'value' => function ($event) {
                        if ($this->jsonstring instanceof Model) {
                            $this->jsonstring = json_encode($this->jsonstring->attributes);
                        }
                    }
            ],
        ];
    }

[lynicidn]

also can validate submodel on before validate and set error on owner as array

[qiangxue]

@Ragazzo The problem with afterFind() is that it only works if your AR object is populated from DB query. If your AR object is newly created or if the attribute needs to be modified, you may not get the expected object representation of the attribute.

@dizews If you don't want bidirectional changes, just don't implement the setter.

[Ragazzo]

@qiangxue yes, you right ) also as for bidirectional changes, why one should handle them, is not it the case when you should avoid hitting attribute directly, just use provided object as need?

[mdmunir]

How about this approach
You can do like this

class JsonBehavior extends ConverterBehavior
{
    protected function convertToStoredFormat($value)
    {
        return json_encode($value);
    }

    protected function convertFromStoredFormat($value)
    {
        $array = json_decode($value);
        return $this->arrayToObjectRecrusive($array);
    }

    private function arrayToObjectRecrusive($array)
    {
        foreach($array as $key=>$value){
            if(is_array($value)){
                $array[$key] = $this->arrayToObjectRecrusive($value);
            }
        }
        return (object)$array;
    }
}

usage

function behaviors()
{
    return [
          [
                'class'=>JsonBehavior::className(),
                'attributes'=>[
                    'jsonObject' => 'jsonstring' 
                ]
          ],
    ]
}

// in application

echo $model->jsonObject->property;

Is a another reason to put this behavior as official? :D

[dizews]

@mdmunir thanks!

[spiritdead]

@cebe exist a option for add this behavior for yii2 ?

[cebe]

@spiritdead add what exactly? there are a lot of different proposals that cover specific cases