Add rest_framework.filters.OrderingFilters to TemplateViewSet filter_…

[richardhadden]

#339 Sorting not implemented; added the rest_framework OrderingFilters, which allows filtering on fields using ordering param

[SteffRhes]

Tested. Works.

Just FYI: I also quickly tested the unlikely edge-case where an entity has an attribute ordering since the REST params can not distinguish between entity attributes and "meta parameters" such as ordering defining the order of results.

If an entity now has an attribute ordering, then drf will use that instead of interpreting it as the order of results.

E.g. I gave a place an ordering field and in one place instance I gave this field the value "name". Now when using ?ordering=name then it will only return that one place and not any others.

[richardhadden]

Nice edge-case testing! I guess this is the case whatever you call the meta-parameter for sorting — always a chance someone will use that as a field name (maybe ordering is chosen by DRF as default as it's less likely to be a field name: sort can be a synonym for type/genre etc.)