I use DRF extension to se json list for model, and there i can debug with debug-toolbar that GET request, but how can i debug POST and
If you need to intercept the request/response and apply your own processing then you can add your custom mixin as described in this answer.
But in the most trivial scenario, given that you do a test POST request (or PUT), for example, with python requests:
import requests
response = requests.post('http://localhost:8000/person', json={"name": "dinsdale"})
Then you can get the error message with
print(response.text)
In most cases the output will contain the failure reason that you were looking for, e.g. 'age' is required.
You can also do the same thing with curl from a terminal:
curl -vv --header "Content-Type: application/json" \
--request POST \
--data '{"name":"dinsdale"}' http://localhost:8000/person/