Yii2: 2.0.16 broke JSON responses

[lourdas]

What steps will reproduce the problem?

Request content by json. For example, I use yii\jui\AutoComplete for a autocomplete box, but when I type, nothing happens, because I get a incorrent JSON response. I get the JSON object plus a null string at the end of it.

What is the expected result?

I should get the autocomplete popup appear.

What do you get instead?

Nothing. The popup does not appear, since the response cannot be parsed correctly.

Additional info

| Q | A
| ---------------- | ---
| Yii version | 2.0.16
| PHP version | 7.2.14
| Operating system |Linux

This is related to issue #17094 with response http status 204. This issue is for http response 200 (it has content). Downgrading to 2.0.15.1 fixes the issue.

[rob006]

How do you generate this JSON response?

[lourdas]

With something like this:

$result = Yii::$app->db->createCommand($query)
    ->bindValue(':afm', $term . '%', \PDO::PARAM_STR)
    ->queryAll();
Yii::$app->response->format = Response::FORMAT_JSON;
echo Json::encode($result);
Yii::$app->end();

in the controller action.

[rob006]

You should not echo response in controller, you should return it like:

$result = Yii::$app->db->createCommand($query)
    ->bindValue(':afm', $term . '%', \PDO::PARAM_STR)
    ->queryAll();
return $this->asJson($result);

[lourdas]

Ok, I didn't know that one. Yes, it works fine. Thanks! Sorry for the noise.

[j0hnh]

If you still want to __end__ the app,you can change the code
from

...
Yii::$app->response->format = Response::FORMAT_JSON;
echo Json::encode($result);
Yii::$app->end();

to

...
$this->asJson($result);
Yii::$app->end();

[cebe]

@j0hnh that will not send the Response. The correct way is to return the Response object and let yii finish the request response-workflow.