Can buttons send back slot values in Rasa 2?

For early version of rasa, I’ve the code as below, which works fine and we can set slot value with clicking of buttions.

  utter_ask_feedback_button:
  - buttons:
    - payload: /feedback_button{"feedback_value":"positive"}
      title: πŸ‘
    - payload: /feedback_button{"feedback_value":"negative"}
      title: πŸ‘Ž
    text: Do you like it?

However, in Rasa 2, I got the warnings:

2020-11-12 21:44:02 ERROR    rasa.core.nlg.interpolator  - Failed to fill utterance template '/feedback_button{"feedback_value":"positive"}'. Tried to replace '"feedback_value":"positive"' but could not find a value for it. There is no slot with this name nor did you pass the value explicitly when calling the template. Return template without filling the template.
Traceback (most recent call last):
  File "/home/sz/py36-bert110-grakn181-rasa203/lib/python3.7/site-packages/rasa/core/nlg/interpolator.py", line 28, in interpolate_text
    text = text.format(values)
KeyError: '"feedback_value":"positive"'
2020-11-12 21:44:02 ERROR    rasa.core.nlg.interpolator  - Failed to fill utterance template '/feedback_button{"feedback_value":"negative"}'. Tried to replace '"feedback_value":"negative"' but could not find a value for it. There is no slot with this name nor did you pass the value explicitly when calling the template. Return template without filling the template.
Traceback (most recent call last):
  File "/home/sz/py36-bert110-grakn181-rasa203/lib/python3.7/site-packages/rasa/core/nlg/interpolator.py", line 28, in interpolate_text
    text = text.format(values)
KeyError: '"feedback_value":"negative"'

When reading the docs of Rasa 2, it says

It seems, the message sent from the user to the assistant is only the intent. My question is that, it’s possible to send back slot value like before?

Thanks

By the way, when runing the code, the slot value seems passed, but the warning is always there. Need some help to correct the warnings.

@yiouyou

Can you please try:

  utter_ask_feedback_button:
  - buttons:
    - payload: /feedback_button{{"feedback_value":"positive"}}
      title: πŸ‘
    - payload: /feedback_button{{"feedback_value":"negative"}}
      title: πŸ‘Ž
    text: Do you like it?

@Tobias_Wochinger It’s working, thanks! Double β€œ{}” is the cure.