Setters for reference_time and timezone in Context.

[hfinck]

People should be able to set the reference_time and timezone to their liking so I added the appropriate setters for that.

As we only accept a date time interface we can make sure that it is properly formatted as required by wit.ai.

public function setReferenceTime(\DateTimeInterface $dateTime)
{
    $dt = $dateTime->format(DATE_ISO8601);
    $this->add('reference_time', $dt);
}

Same thing for the time zone. It will error out if a non-valid timezone string is applied.

We also make sure that an empty context is serialised to an empty JSON object. Otherwise we would get an empty array, which will be rejected by wit.ai with an error.

    public function jsonSerialize()
    {
        return $this->data ?: new \stdClass;
    }

[tgallice]

I not a big fan of this. Why not just check if the context is not empty before send it like in my PR here?

[hfinck]

Ok, the thing I wanted to make sure is that the Context does not get serialized into an array, since that would be serialized the wrong way.
In your PR you have a check in place where we do not send an empty Context. So for that matter it would be fine to just return the data array with no check at all. Alright with that? I then would restore that line to the previous state.

[tgallice]

@hfinck yes you right it can be usefull, but it's should not return a stdClass, return null will be better ? What do you think ?

[hfinck]

I'm just returning data now. It would't be good to just return null. I can live with the empty array and taking care of it in the ConversationApi.

[tgallice]

👍
@hfinck Just fix the tests and I will merge it. Thank for this !

[hfinck]

@tgallice All good. Go ahead.