Mongoose Validation Error occurs on OpenShift but not local version - node.js

Question

I am migrating my Node.js server with Mongoose to OpenShift and an error occurs on the live server that I cannot reproduce on my local WebStorm built-in server.
I get the error message:
undefined: {
properties: {
message: "Cannot read property 'options' of undefined"
type: "cast"
}-
message: "Cannot read property 'options' of undefined"
name: "ValidatorError"
kind: "cast"
}
This occurs when I try to push an element into the items array and save, for the following schema:
var listSchema = new mongoose.Schema({
owner: {type: mongoose.Schema.Types.ObjectId, ref: 'User', required: true},
name: {type: String, required: true},
items: [
{
name:{
type: String,
required:true
},
quantity:Number,
check: Boolean
}
]
});
The local version that works, and the OpenShift version use the exact same code. The code that adds the new element is:
var listId = req.params["id"];
if (sessions.verifyToken(userId, token)) {
var data = req.body;
var query = List.findOne({
owner: userId,
"_id": listId
});
query.exec(function(err, list) {
...
//handle error and null (omitted for brevity)
...
list.items.push({ // error thrown here
name: req.body["name"],
quantity: req.body["quantity"],
check: false
});
list.save(function(err, list) {
if (err) {
var message = "Unable save appended list to persistent memory";
console.log(message, err);
res.setHeader("content-type", "application/json");
res.send(JSON.stringify({success: false, message: message, error: err}));
return;
}
res.setHeader("content-type", "application/json");
res.send(JSON.stringify(list));
});
});
I thought that maybe an earlier version of the schema had added a constraint, so I dropped the lists collection, but the problem did not go away.
What might be different on the OpenShift PaaS that could be causing the error?
[Edit]
Just for fun, I removed all required fields from items and now the error message is this:
"undefined": {
"properties": {
"message": "Cannot read property 'options' of undefined",
"type": "cast"
},
"message": "Cannot read property 'options' of undefined",
"name": "ValidatorError",
"kind": "cast"
},
"owner": {
"properties": {
"type": "required",
"message": "Path `{PATH}` is required.",
"path": "owner"
},
"message": "Path `owner` is required.",
"name": "ValidatorError",
"kind": "required",
"path": "owner"
}
This seems to suggest that the Model loses its owner field somewhere between finding the list and saving it again.
[/Edit]

Answer 1

On OpenShift, when you find or findOne a model that has a required reference to another entity, that field will not be automatically filled in. Thus, when save is called, the field will be missing. Change
var query = List.findOne({
owner: userId,
"_id": listId
});
to
var query = List.findOne({
owner: userId,
"_id": listId
}).populate("owner");
For some reason, this does not work the same in every environment. For some, either it does automatically populate the reference field, or it assumed it unchanged when saving. I'm not sure which.