Mongoose populate specific array instance

Question

I tried lot of combination didnt work out so need your help.

Consider your have a document schema and versions

var VersionSchema = mongoose.createSchema("version", {
    version:  { type: Number},
    metadata: { type: Schema.Types.ObjectId, ref: 'Metadata' }
});

var documentSchema = mongoose.createSchema("document", {
    projectId: { type: Schema.Types.ObjectId},
    versions:  [VersionSchema],
    deleted:   { type: Boolean, default: false}
});

data will look like this

{
    _id: a58107da0dc3da020998787c,
    projectId: 09434766ab47c29609972596,
    deleted: false,
    versions: [
        { _id: 9ac67dc1b84df1ff09988ea1, version: 1, Metadata: [Object] },
        { _id: 9ac67dc1b84df1ff09988ea2, version: 2, Metadata: [Object] }
    ]
}

I want to populate only latest version document..say version 2..not all sub versions..

I tried this but need help..

Document.findOne({ projectId: projectId }, function(error, document) {
    var options = [{
        path: 'versions.Metadata,
        model: Metadata
            //,
            //match: { version: 2 }
    }];
    Version.populate(document, options, function(err, doc) {
        deferred.resolve(doc);
    });
});

Might just be a typo, but shouldn't it be `path: 'versions.metadata',` ? — JohnnyHK, Feb 08 '15 at 01:53
@JohnnyHK the populate works already..but i want to only populate version:2 Metadata not first record.. — procoder, Feb 08 '15 at 07:53
`match` is applied against the `Metadata` fields, not the fields of the `versions` elements. — JohnnyHK, Feb 08 '15 at 15:15
@johnnyHK is there a possibility to populate only one element in versions?? — procoder, Feb 09 '15 at 03:41
It sounds a bit inelegant, but just find that `version: 2` element in JavaScript and then call `Version.populate`, passing that element with the appropriate options to populate its `metadata` field. — JohnnyHK, Feb 09 '15 at 04:05

score 0 · Answer 1 · answered Feb 09 '15 at 17:47

Document.findOne({ projectId: projectId }, function(error, document) {
    var options = [{
                    path: 'versions.Metadata,
                    model: Metadata
                   }];
    var version = document.versions[document.versions.length - 1];
    Version.populate(version, options, function(err, updatedVer) {
         deferred.resolve(updatedVer);
        });
  });

Mongoose populate specific array instance

1 Answers1