Allow user search with multiple attributes

[tkharju]

Currently query /api/1/user?dreamschool=123&foo=bar filters UserAttributes by only picking either of the parameters (randomly).

DoD: User queryset is filtered using all GET parameters

Ref:

eca-auth-data/authdata/views.py

Line 144 in c37e991

break # only handle one GET variable for now

This is the reason why following test failed: https://travis-ci.org/educloudalliance/eca-auth-data/jobs/102996338

[derega]

The documentation for that endpoint says:

Query is made by GET parameters. Only one parameter is allowed. The parameter
consists of an attribute name and an attribute value.

Where and why this endpoint should support more than one query parameter?

[derega]

The failing test:

eca-auth-data/authdata/tests/test_views.py

Line 289 in c37e991

def test_get_object_with_attributes(self, requests_mock):

[tkharju]

We discussed about this with @derega and came to the conclusion that it would be better to do the tests at this point only with one attribute. In other words mpass-data works so that /api/1/user?dreamschool=123 is valid but /api/1/user?dreamschool=123&foo=bar is not.
Current implementation is not deterministic. If user makes query against the spec by giving two or more attributes, it is possible that at times the results differ, as only the first attribute is used for filtering but the order of get-attributes may change even between similar requests.