This is one followup of MDL-30480 (where we went back to allow custom objects to be passed). Also this should be consider a "sister" of MDL-29894 and both should be considered, decided and implemented at the same time, surely for 2.3 and without backporting.

Some comments from the original issue:

• It is a new feature, since 2.0 we have not supported custom objects there.
• I'm not sure if the way is to allow them or to debug about them and provide fallback conversion using get_object_vars(). This needs to be decided before implementation. And once decided:
  • It must cover all insert/update operations, xx_raw() ones included.
  • It requires specific unit-tests, both stdclass and object with privates/magics should be tested if we really want support to them.

Here it is the original commit, that could be a good base - from MDL-30480 - for continuing here):

https://github.com/stronk7/moodle/compare/master...wip_MDL-30508.objects_on_moodle_database