Fix the filter for hasManyThrough relation

[jannyHou]

Description/Steps to reproduce

A follow up issue for strongloop/loopback#4006

Cloudant connector has the problem, haven't checked other connectors:

When many-to-many relation has a through model, for example

• Team hasMany Resource through TeamResource
• Resource hasMany Team through TeamResource

Query a team with its resources included using Team.findById(teamId, {include: {relation: 'resources', scope: {limit: 100}}})

The connector first finds all the through model instances using teamId, then do a recursive find for each of the teamResources using its resourceId, and the limit filter is applied on it, which causes the problem.

As a workaround fix, PR #196 allows user to define a globalLimit to retrieve all the related model instances.

The real fix should:

• compare with the other connectors see how they deal with include filter
• investigate the possibility to find related model from through model in one query not a bunch of recursive queries, at least in the cloudant connector
• if it's feasible to apply limit/skip/offset on the related model, create a PR for such a fix. If it's restricted by design, then document it and this workaround.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

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