Is it possible to serialise peewee.Expression?
No, not really or not officially. You can see how the [dynamic filters work in flask-peewee](http://docs.peewee-orm.com/projects/flask-peewee/en/latest/admin.html#filters): https://github.com/coleifer/flask-peewee/blob/master/flask_peewee/filters.py

Probably the easiest thing to do though is to use the django-style query apis, eg `field__eq=value`. These can be passed to `model.filter()` like Django.

Lastly, we have irc on libera #peewee, or you can ask general questions on stack overflow. I regularly check SO and try to provide help there just fyi. @coleifer Thanks for you answer. I am trying to implement my own json decoder, looks like it is that hard to represent pewee.Expression tree in json. 
it is not an issue, but I didn't find other communication channel to get some ideas in how to serialise peewee.Expression to pass it to the API and later use there as filter in the query. Thanks