mongoose populate field without ref option

Question

I have 3 schema:

var User1Schema = new Schema({
    name: {type:String , trim: true, required: true },
    status: {type:Number, required: true, default:1}
},{collection:"user_1"});

,

var User2Schema = new Schema({
    name: {type:String , trim: true, required: true },
    email: {type: String, required: true, index: {unique: true} },
    status: {type:Number, required: true, default:1}
},{collection:"user_2"});

and

var ConversationSchema = new Schema( {

    participants: [{user:{type: ObjectId, required: true}],
    creator: {type: ObjectId, required: true},

    status: { type:Number, required: true, default:1 }

}, { collection:"conversation" } );

In ConversationSchema I have creator field whic has now ref option, because it can be type of User1Schema or User2Schema.

How can I populate creator field using mongoose

See the `mongoose-dbref` plugin: https://github.com/goulash1971/mongoose-dbref — JohnnyHK, Jan 31 '13 at 15:15
Here's a more up-to-date branch of `mongoose-dbref` https://github.com/apiaryio/mongoose-dbref. However, if at all possible, you should try to just change your schema instead of branching it: http://stackoverflow.com/questions/7617002/dealing-with-schema-changes-in-mongoose — mjhm, Jan 31 '13 at 16:43

score 26 · Accepted Answer · answered Feb 15 '13 at 00:03

26

Conversation.find().populate('creator', null, 'User2').exec(callback)

The docs aren't clear. Will update soon.

Also, the syntax for this will be simpler in v3.6.

answered Feb 15 '13 at 00:03

aaronheckmann

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This allows for a multiple-reference field, I imagine? e.g., a `_author` of a document might be a `User` ObjectId _or_ it might be an `Organization` ObjectId? – Eric Martindale Jun 24 '13 at 21:03
2

yep, if you know which model is necessary you can specify this at query time. – aaronheckmann Jun 26 '13 at 19:34
Does this also work for a Mixed type field where the path refers to an ObjectId? – Kevin Wang Oct 13 '13 at 03:25
@KevinWang It appears to!. Just make sure the 3rd parameter of the populate call is a string with the same name as the mongoose Model you're trying to populate. – Raven Dreamer Jan 21 '14 at 20:03
1

What if I want to populate creator in multiple models e.g 'User1' and 'User2'? I see only the last specified model is populated and all the previous models return null. – dantheta Aug 11 '14 at 04:02
can we save the model name in the ConversationSchema as a field and then pass it to populate ? – Anoopsingh Bayes Oct 13 '14 at 06:49
@aaronheckmann do u have answer of anoopsingh/dantheta question? – Prashant Tapase Mar 17 '17 at 11:22

score 1 · Answer 2 · answered Mar 27 '19 at 10:09

As of 27th March 2019 the way to do so is:

1) Setting the field you want to populate as a ObjectId without providing a ref.

var eventSchema = new Schema({
  name: String,
  // The id of the corresponding conversation
  // Notice there's no ref here!
  conversation: ObjectId
});

2) While making the query pass the model for the schema along with the query:

Event.
  find().
  populate({ path: 'conversation', model: Conversation }).
  exec(function(error, docs) { /* ... */ });

REF: https://mongoosejs.com/docs/populate.html#cross-db-populate

mongoose populate field without ref option

2 Answers2

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