jinja templating not working (1.2.0-rc2) requires undocumented config

Expected results

Following documentation, running for instance this query should work (from sql lab)

SELECT  *
FROM mytable
WHERE username = '{{ current_username() }}'

should work and return results.

Actual results

{{ current_username() }} is not interpreted at all, is considered as a String. Hence the result does not work.

Note that '{{ url_param('myparam') }}' does not work either

looks like no templating interpretation is done.

Used to work fine in 0.38

Does not work in 1.2.0-RC2

I don’t know where to look for detailed executions logs. I had a look un query table of superset schema, query was not traced interpreted there but maybe it’s the expected result.

Screenshots

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How to reproduce the bug

1. Go to ‘SQL Lab’
2. Enter a query using Jinja templating
3. See issue

Environment

(please complete the following information):

• superset version: Superset 1.2.0 (1.2.0-RC2 actually)
• python version: Python 3.7.9
• node.js version: not present in container

Checklist

Make sure to follow these steps before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven’t found one similar.

Additional context

Add any other context about the problem here.

[maltoze]

Hope this can help. #15246

[squalou]

for the records, this works in superset_config.py

It should really be added here : https://superset.apache.org/docs/installation/sql-templating

FEATURE_FLAGS = {
    "ENABLE_TEMPLATE_PROCESSING": True
}

BUT it still doesn’t work in SQL LAB. It works when used elsewhere