mongoose findOne() call not saving and no error in output

Question

I'm doing a simple findOne() and saving the doc within it, but for some reason it's not working. I've outputted the object and the output in console is correct, but after the save(), I take a look at my mongodb and it didn't save. I'm not sure if there is some sort of option I'm supposed to set. Here is my code:

var1 = "data1";
var2 = "data1field1";
Model.findOne({'_id':some_id}).exec(function(err, doc) {
    if (err) return console.error(err);
    (doc.data[var1][var2][0] += 1;
    console.log(doc.data.data1);
    doc.save(function (err) {
        if(err){console.log(err);}
        console.log('success');
    });
});

Here is my schema:

var modelSchema = new mongoose.Schema({
    'data':{
        'data1':{
            'data1field1':[{type: Number}],
            'data1field2':[{type: Number}]
        },
        'data2':{
            'data2field1':[{type: Number}],
            'data2field2':[{type: Number}]
        }
    }
});
var Model = mongoose.model('model', modelSchema);
module.exports.Model = Model;

Say I create an instance of this schema where data.data1.data1field1 is an array of two numbers [0,0], the output for "console.log(doc.data.data1);" would be:

{
    data1field1:[1,0],
    data1field2:[0,0] }
success

But the save does not happen. I'm new to mongoose/mongodb so there is probably a simple fundamental thing I'm missing.

NOTE: I cannot use Model.update({},{$inc {}}) because I'm using variables to select which data object to change, and because of the literals in .update(), it is impossible.

Thanks.

Answer 1

So mongoose has some smarts to automatically detect changes when you do simple property sets like myModel.name = 'Steve'. However, when you access deeply nested schemas and change properties deep in the graph, the top level document cannot auto-detect this. So you need to tell mongoose what you changed.

doc.markModified('data.' + var1 + '.' + var2);

If you get the correct incantation of that, mongoose will be able to save your change.