Hi,
I have dashboard on which I would like to set value via slider and send it in JSON.
As I can see as for now its only possible to recive data from JSON not setting? Any plans to change that?

Color picker is best example how it could work.

Slider can set value in JSON. Just set your topic with JSON-value, set field which slider value from, then slider wrap your value in last JSON value and send to broker.

LeszekLeo it works like you need: if you specify paylad path as "value" and push the message e.g.
{"command":"setSomething","value":10}
then when you move the slide to value e.g. 35, then you'll receive pushed message
{"command":"setSomething","value":35}