javascript - using populate to display username instead of id -

i'm running expressjs mongoosejs made connection between collections customerid below:

. . /** * customer schema */ var customerschema = new schema({     id : number,     name: string,     joined: { type: date, default: date.now },     city: string });  mongoose.model('customer', customerschema); . . /** * order schema */ var orderschema = new schema({     id : number,     products: [schema.types.mixed],     total: number,     comments: string,     customerid: {type: number, ref: 'customer'} });  mongoose.model('order', orderschema); . . exports.customerorders = function (req, res) {    return order.find({customerid: req.params.customerid}, function (err, orders) {        order.populate(orders, {path: 'customerid', model: 'order'}, function (err, orders) {         if (!err) {             return res.json(orders);         } else {             return res.send(err);         }     }); }); }; 

the above code generate following error:

{   message: "cast objectid failed value "1" @ path "_id"",   name: "casterror",   type: "objectid",   value: 1,   path: "_id" } 

the relation between objects id no _id

please me use populate method in right way.

thanx,

mongoose's populate functionality supports using _id field find related doc in referenced collection.

so can't use field id , you'd need change customerid be:

customerid: {type: objectid, ref: 'customer'} 

in orderschema , populate _id value of customer instead.