[5.5] Cast to object before json_encoding

[alepeino]

Both Support\MessageBag and Eloquent\Model hold their data as an associative array, and their JSON representation is the simple the "json_encode-ing" of that array. It's an implicit contract that a key-value structure is returned.

However, when that array is empty, the resulting JSON is [] instead of the expected {}. Thus, that contract is broken, from the point of view of the consumer of the json string.

Consider (related and following up to #21605 ) a Vue component to which I'm passing a model and the validation errors.

<user-form :model="{{ $user }}"
           :errors="{{ $errors }}"
></user-form>

While the component expects an object, if the error bag (or, less likely, the model) is empty, an empty array is effectively passed. This change ensures the resulting JSON represents an object.

[Dylan-DPC-zz]

This is a breaking change.

[sisve]

I'll ignore the fact that you decided to send a PR that may break existing 5.5 installations because you're unhappy with the data format in your specific use case, and instead ask you if forgot to write tests, or just forgot to add those test files to the commit?

[alepeino]

@sisve Well, I tried to provide reasons as to why this could be considered the breaking of a contract (it's a different data type from the perspective of a JS client for instance), so it's not about "my specific use case", is it.

Speaking of breaking, I do realize this may be potentially breaking, so I will re submit it to a different branch.

[Dylan-DPC-zz]

@alepeino when you say it fails for a use case, it is better to provide a test that shows the use case.

[deleugpn]

Send it to Master

[alepeino]

@Dylan-DPC @deleugpn will do, thanks!