"contains" filter for collections should disregard reference version if not provided

[paynejd]

Last year we added the contains parameter to filter the list of collections returned by those that contain a specified reference. For example:

https://api.staging.openconceptlab.org/orgs/PEPFAR-MOH-UG/collections/?contains=/orgs/PEPFAR-MOH-UG/sources/PEPFAR-Alignment-Indicators/concepts/mCVvMl1sIua/5ab1b25f61ce75004c1456e8/

However, it apparently only works if you include the specific version of the concept or mapping. For example, this does not work currently:

https://api.staging.openconceptlab.org/orgs/PEPFAR-MOH-UG/collections/?contains=/orgs/PEPFAR-MOH-UG/sources/PEPFAR-Alignment-Indicators/concepts/mCVvMl1sIua/

The correct behavior is that it should match the concept/mapping version if it is provided (the current behavior), but that it should match just the concept/mapping ID if no version information is provided.

[paynejd]

FYI this applies to mappings as well as concepts. This query works as expected:

https://api.staging.openconceptlab.org/orgs/PEPFAR-MOH-UG/collections/?contains=/orgs/PEPFAR-MOH-UG/sources/PEPFAR-Alignment-Indicators/mappings/5ab1b6d561ce75004c1457c9/1/

But this one (when removing the mapping version /1/) does not:

https://api.staging.openconceptlab.org/orgs/PEPFAR-MOH-UG/collections/?contains=/orgs/PEPFAR-MOH-UG/sources/PEPFAR-Alignment-Indicators/mappings/5ab1b6d561ce75004c1457c9/

[paynejd]

Potentially implement a strict=true parameter which would only match exactly what was passed in the contains parameter

[rkorytkowski]

An expression is currently stored in a field in an embedded document within a collection. Our mongodb-djangoe-engine version does not support partial queries in such a structure. We would have to resort to a raw mongodb query, which then cannot be easily extended with additional filters (e.g. access restrictions). #86 needs to be implemented first, which will simplify the model and allow for such queries.