Populate a field in an array (and place data in that field)

[robertbart]

Steps to reproduce

This issue is very similar to #142.

I'm attempting to populate a field inside an array, with the data from the population replacing the field.

This is the data I'm working with:
Users

{ _id: '111', name: 'alice', age: '19' }
{ _id: '222', name: 'bob', age: '18' }

Team

{
  _id: '555',
  name: 'Alpha',
  members: [
    { user: '111', role: 'leader' },
    { user: '222', role: 'member' }
  ]
}

And the code I have in an attempt to do this.

{
    childField: "_id",
    nameAs: "members.user",
    parentField: "members",
    select: (_, parent) => parent.members ? ({ _id: { $in: parent.members.map(member => member.user) } }) : {},
    service: "users",
}

Expected behavior

{
  _id: '555',
  name: 'Alpha',
  members: [
    {
      user: { _id: '111', name: 'alice', age = '19' },
      role: 'leader' 
    },
    {
      user: { _id: '222', name: 'bob', age: '18' },
      role: 'member' 
    }
  ]
}

Actual behavior

Adds this to the response:

"_include": [
        "members.user"
]

Alternative 'half-working' solution.

The following code:

{
    childField: "_id",
    nameAs: "users",
    parentField: "members",
    select: (_, parent) => parent.members ? ({ _id: { $in: parent.members.map(member => member.user) } }) : {},
    service: "users",
}

produces:

{
  _id: '555',
  name: 'Alpha',
  members: [
    { user: '111', role: 'leader' },
    { user: '222', role: 'member' }
  ],
  users: [
    { user: '111', role: 'leader' },
    { user: '222', role: 'member' }
   ]
}

where I do have all the data I need but not formatted in a way that I want (the user models being placed into the user field in the members list).

[eddyystop]

The way to address your needs is to have a preliminary hook that extracts the foreign ids into a format acceptable to populate.

Iterating through an array of objects is difficult to implement. And where does it end? Those objects may themselves contain arrays of objects.

You can submit a PR that fully addresses this issue if you're interested in to doing so.

[robertbart]

As a quick workaround, I changed the nameAsField to user, which created a list of users in the root of the object, and then created a second hook which moved them to their correct place.

When I'm done with prototyping the current project I'm working on, I'll come back and create a more permanent and better solution.

[eddyystop]

The new fastJoin hook can handle this scenario, as well as others populate can't.

It also makes roughly 10% of the service calls that populate needs, i.e. 2 calls instead of 20.

https://feathers-plus.github.io/v1/feathers-hooks-common/index.html#fastjoin
https://feathers-plus.github.io/v1/feathers-hooks-common/guide.html#fastJoin