How to decrease value inside object nested in an array using Node.js and MongoDB/Mongoose

Question

Using moongoose for Node.js, I'm trying to go through each object in the "STEPS" array and decrease the stepid by 1. Using this schema below:

"appid": 1,
"steps": [
            {
                "name": "step4",
                "stepid": 4,
            },
            {
                "name": "step5",
                "stepid": 5,
            }               
         ],
"appname": "myapp"

Here's how I tried is using .update:

app.db.models.myApps.update(
        {'appid': 1, 'steps.stepid': { $gt: 3 }},
        { $inc: { 'steps.$.stepid': -1 } },
    { multi: true }
);

But I can't seem to get it to work correctly. I was able to play around with the code and get it to update but it would only update 1 of the objects in the array, whereas I would like it to go through each object in the array and decrease by 1.

Should I break it out and first use find and then update? The old dev in me says to do a for loop but I know that's not the right way to do it with node.

Any help or suggestions are greatly appreciated! Thanks!

You are correct, it is, and that sucks because it's not supported :\ — sMyles, Sep 10 '13 at 02:23

score 0 · Accepted Answer · edited May 23 '17 at 12:11

Unfortunately this appears to be an issue with mongodb which does not support it.

Per: How to Update Multiple Array Elements in mongodb

And here: https://jira.mongodb.org/browse/SERVER-1243

For now a workaround would be this:

function convertDirectMessages(id, cb) {
    Conversation.collection.update(
        {'messages.context': 'direct'}, 
        {$set:{'messages.$.context': {type:'direct'}}}, 
        {safe:true, multi:true},
        function(err, updated) {
            if (err) return cb(err);
            if (updated) return convertDirectMessages(id, cb);
            cb();
        }
    );
}
convertDirectMessages(posted._id, this);

How to decrease value inside object nested in an array using Node.js and MongoDB/Mongoose

1 Answers1