Comment 3 for bug 1867899

Reviewed: https://review.opendev.org/713886
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=241ea888c6993ac045cf12d6b61d4e1a1ff29ad3
Submitter: Zuul
Branch: stable/train

commit 241ea888c6993ac045cf12d6b61d4e1a1ff29ad3
Author: Renat Akhmerov <email address hidden>
Date: Fri Mar 13 16:55:25 2020 +0700

    Fix ContextView JSON serialization

    * With disabled YAQL data output conversion, YAQL may return
      instances of ContextView which can't be properly saved into
      DB. This happens because Mistral serialization code doesn't
      turn on JSON conversion of custom objects, and they are just
      ignored by the "json" lib when it encounters them.
    * Fixed how Mistral serializes context for Javascript evaluation
      to address the same problem.
    * Implemented __repr__ method of ContextView.
    * Removed logging of "data_context" from YAQL evaluation because
      previously it was always empty (because the string represetation
      of ContextView was always "{}") and now it may be very big, like
      megabytes, and the log gets populated too fast. It makes sense to
      log YAQL data context only when an error happened. In this case
      it helps to investigate an issue.
    * Added all required unit tests.
    * Fixed the tests for disabled YAQL conversion. In fact, they
      didn't test it properly because data conversion wasn't disabled.

    Closes-Bug: #1867899
    Change-Id: I12b4d0c5f1f49990d8ae09b72f73c0da96254a86