I have a User collection and a Task Collection. Many Users can have many Tasks, and Many Tasks can have many Users. The proper way I believe in doing this is the following models:

var UserSchema = new Schema({
    id: ObjectId,
    username: { type: String, required: true },
    assignments: [ {type : mongoose.Schema.ObjectId, ref : 'Assignment'} ]
});

var TaskSchema = new Schema({
    id: ObjectId,
    title: { type: String, default: '' },
    information: { type: String, default: '' },
    assignments: [ {type : mongoose.Schema.ObjectId, ref : 'Assignment'} ]
});

var AssignmentSchema = new Schema({
    id: ObjectId,
    isCompleted: { type: Boolean, default: false },
    completionDate: { type: Date, default: null },
    tasks: [ {type : mongoose.Schema.ObjectId, ref : 'Task'} ],
    users: [ {type : mongoose.Schema.ObjectId, ref : 'User'} ]
});

If the above models are correct, how do you insert a Task with multiple user assignments? I understand that you would create the Task document first to get its ObjectId, but after that would you just insert all of the assignments into the Assignment collection (with their proper Task and User objectId's) and thats it? Or would I have to insert all of the assignments then edit each individual User and Task to insert the AssignmentId into their assignments property.

I am sure there is a stack over flow question like this already, but I have not been able to find one. Any help is appreciated!