feat(query): custom populate query

[muniperez]

Do you want to request a feature or report a bug?
feature

What is the current behavior?
In order to populate a query you need to provide a child and a root.

What is the expected behavior?
Let's say you have a list of items AND you have to apply pagination on them.

{
 "userFeed" : {
  "{user_id}" : {
   "posts" :  {
     "{post_id}": true,
     "{post_id}": true,
     "{post_id}": true,
     "{post_id}": true
    }
  }
 }
}

Currently, in order to populate a request, you need to provide both "child" and "root".

But in this case, if I want to apply a pagination, although the root is known, there's no child because the path has to be:

/userFeed/{user_id}/posts&limitToLast={number}

My request is to add a populate query for items in a list where the child is the key of each item.

Thank you.

[prescottprue]

A few others (including some over gitter) have mentioned that this "populate list of child keys " would be a nice feature of populate. Thanks for posting.

[prescottprue]

I believe this may be the same or similar to the feature requested in #140

[prescottprue]

#461 asked for similar functionality. As mentioned there: a work around could be to query for that path directly with query params you want (i.e. limitTo: 10). Note that you may want to use storeAs if you are querying data within your profile (in order to not collide with any profileParamsToPopulate).