Populate mongoose array of objects

Question

Populate mongoose array of objects

I have a mongoose model that looks like this:

var ModuleSchema = new Schema({
systems: [{
    system: {
            type: Schema.ObjectId,
            ref: 'System'
        },
            quantity: {
            type: Number
        }
    }]
});

mongoose.model('Module', ModuleSchema);

Basically the ModuleSchema.systems.$.system property will not get populated. The property belongs to an object in the array of objects. I have tried everything to get it to populate but it just won't happen.

I tried the following syntax for populating but not sure what might be wrong because I still don't get back the populated System property.

Module.findOne({project: pId}).sort('-created')
    .populate('systems.system')

node.js
express
mongoose

Answer 1

It wont work as system is not a property of systems. You need to populate it like

Module.findOne({project: pId}).sort('-created')
    .populate('systems.0.system').exec(function (err, doc){})

Module.findOne({project: pId}).sort('-created')
        .populate('systems.1.system').exec(function (err, doc){})

So you should have a for loop and iterate over it to populate all the documents. Else you should modify your model to make it work better.

var ModuleSchema = new Schema({
systems: [{
    system: {
            type: Schema.ObjectId,
            ref: 'System'
        },
            quantity: {
            type: Number
        }
    }]
});

Change your model to this and it will make easy for you.

 var ModuleSchema = new Schema({
        systems: {
           system: [{
                type: Schema.ObjectId,
                ref: 'System'
           }],
           quantity: {
           type: Number
        }

        }
    });