Question

This is my first look in anger an node.js and mongodb so its possible I’ve done something silly or missed something obvious but given the document and the query below, why might a an empty object be returned?

1 Document example

{  
    __v: 0, 
    _id: ObjectId("50bf7f12fc71b74f3b000001"),
    amount: 452.23, 
    categoryId: 13, 
    created: ISODate("2012-12-05T17:06:26Z"), 
    description: "Test", 
    typeId: 1, 
    updated: ISODate("2012-12-05T17:06:26Z")
}

2 Problem code

var Schema = mongoose.Schema;  

var Expense = new Schema({  
    description: { type: String, required: true },  
    amount: { type: Number, required: true },  
    created: { type: Date, default: Date.now },
    updated: { type: Date, default: Date.now },
    categoryId: { type: Number, required: true },
    typeId: { type: Number, required: true }
});

var ExpenseModel = mongoose.model('Expense', Expense);

ExpenseModel.aggregate(  
    { $group: { _id: '$typeId', total: { $sum: '$amount' }}}, 
    function (err, summary) {
        if(err){
            return res.send(500, { error: err }); 
        }

        if(summary) {
            return res.send(summary);
        } else {
            res.send(500, { error: 'couldnt find expenses' }); 
        }
    }
);

Answer 1

Changing the name of the collection to Expenses from expenses solved the problem.