Yashua Yashua - 4 months ago 67
Node.js Question

Version error on saving Mongoose docs

I have an issue - not sure if I am doing something wrong or it's a bug. I have some products - each of these has an array of variations. I want to go through some data and load it in these variations but I experience a number of 'VersionError: No matching document found' errors.

Thinking I was having a race condition (I am sequenctially saving the same document for each of its variations that I modify) I used asyc.eachSeries() but that did not help. Loading the error causing documents one at the time does not yield the error so it seems related to some race condition but I cannot track it down.

Schema:

var Product = new Schema({
title: {
type: String,
},
variations: {
type: Array
}
});


Sample code:

// Some data to load - the 'variant' is the index of the variations array above
var records = [{
code: 'foo',
id: '50ba9c647abe1789f7000073',
variant: 0
}, {
code: 'bar',
id: '50ba9c647abe1789f7000073',
variant: 1
}, {
code: 'foobar',
id: '50ba9c647abe1789f7000073',
variant: 2
}];

var iterator = function(item, cb) {
Product.findById(item.id).exec(function(err, product) {
if(err) {
return cb(err);
}
if (product) {
product.variations[item.variant].code = item.code.trim();
product.markModified('variations');
product.save(function(err, p) {
return cb(err);
});
} else {
return cb('Missing product');
}
});
};

async.eachSeries(records, iterator, function(err) {
process.exit(1);
});

Answer

I think the problem is how you've defined your schema. It's much to better to have variant be it's own schema and have the product schema use that as a sub doc instead. I would change it to look something like this:

var Variant = new Schema({
    code: String,
})

var Product = new Schema({
    title: String,
    variants: [Variant]
})

Then you could go through the records like so:

var variants = product.variants
for (i in variants) {
    var variant = variants[i]
    variant.code = records[i].code
    variant.save(function(err) {
        ...
    })
}