Filter child collection based on count

[jgornick]

We've run into a scenario lately where we're trying to filter a collection based on the count of a child collection.

For example, we want to filter users who are assigned to groups. Based on the OData specification, the $count query option or length operator are available to get counts on collections.

For reference how to use these, refer to:

• Example 32 - 4.8 Addressing the Count of a Collection
• Example 43 - 4.12 Addressing a Subset of a Collection
  • GET /users?$filter=groups/$count gt 0
  • GET /users?$filter=groups/$count
• Example 73 - 5.1.1.5.5 length
  • GET /users?$filter=length(groups) gt 0

Does anyone have thoughts on how something like this might be implemented to a Sequelize query?

Thanks!