why efq_views does not support relationships

If you want to use MongoDB you know that it doesn't support JOINs. Nonetheless, both entityreference and taxonomy term reference is supported as much as possible: as a field, as filter on the referenced ID, as an argument on the referenced ID. It's not possible to do more. If you want to list nodes created by users who registered today, you need to add the users created data into mongodb and write your own query. Sorry.

I realize that this is an ancient thread, but my company created a workaround for this issue, effectively creating relationships out of two EFQ views piped together. I'm not sure it's ultimately the best solution, but it does cover the use case of a user who is comfortable with Views, needs EFQ Views with relationships, but doesn't know how to write their own queries.

We're working on getting a sandbox up for the module, but also wanted to gauge EFQ Views users' and maintainers' interest. Would this be of use to anyone?

Will post the link back here once there's a sandbox.