流星Mongo查询集合中数组的子集

Question

I've run into a problem when querying for some stuff.

I have a collection called Guestlists containing guestlists. Each element contains a date and some other stuff together with an array called "list". The "list" array contains elements of each guestlist entry. Every guestlist entry has an "entryOwner" meaning the person who added the entry to the list.

Here is the schema:

Schemas.Guestlist = new SimpleSchema({
  _id: { type: String, regEx: SimpleSchema.RegEx.Id },
  date: { type: Number },
  promoters: { type: [String], regEx: SimpleSchema.RegEx.Id, defaultValue: [] },
  list: { type: Array, defaultValue: [] },
  'list.$': { type: Object },
  'list.$.name': { type: String },
  'list.$.entryOwner': { type: String },
  'list.$.comment': { type: String, optional: true },
  'list.$.accepted': { type: Boolean, defaultValue: false },
  'list.$.rejected': { type: Boolean, defaultValue: false },
})

Now comes the problem. I want to query the database and get 1 guestlist and only the guestlist entries for a specific user-ID.

This is what I tried:

Guestlists.find({_id : guestlistID, list: {$elemMatch: {entryOwner: user._id}}}, {fields: { 'list.$': 1}})

However, that only returns the guestlist with one item in the 'list' array, which is the first one. How can I get ALL the items in 'list' that has the entryOwner I query for?

Also tried this, but gives same result:

Guestlists.find({_id: guestlistID}, {fields: {list: {$elemMatch: {entryOwner: user._id}}}})

It is also important ta keep it as a cursor since I want to return this in my publications

Answer 1

Is this what you're looking for?

 Guestlists.findOne({{_id : guestlistID, list: {$elemMatch: {entryOwner: user._id}}}};

This limits the returned amount of GuestLists to one. It is returned as an object and not as an array of length 1.

Answer 2

EDIT 2016-03-08

Found a solution of how to solve the whole problem!

Now I use a package ( https://atmospherejs.com/jcbernack/reactive-aggregate ) and do exactly as they describe.

In the publication I do my aggregate and then set a client-side collection which to push the data to. Then I subscribe and fetch the data from the client-side collection.

---

Okey, I got some help from the Meteor forums with this.

What I was looking for was to use Aggregate in MongoDB! It does exist a nice package for this: https://github.com/meteorhacks/meteor-aggregate

This is how my code looks now:

guestList = Guestlists.aggregate([
    { $match: {nightclubId: nightclubId, date: dateTime}},
    { $unwind: '$list'},
    { $match: {'list.entryOwner': user._id}},
    { $group: {_id: '$_id', list: {$push: '$list'}}}
  ])

Now my problem is how to return this from my publication to the client.