How to resolve 'The 'cursor' option is required in MongoDB 3.6?

Question

I am implementing single page application and using Angular JS, MongoDB Database. So I am calling aggregation two ways:

With Arguments.
Without Arguments.

When I was using 3.4 version of mongoDb. Then both way was working. But I upgraded mongoDb version from 3.4 to 3.6 then without arguments it is not working. Only with argument aggregation is calling.

when I implemented aggregation without arguments.
Then It is giving me Below error message.

The full response is { 'ok' : 0.0, 'errmsg' : 'The 'cursor' option is required, except for aggregate with the explain argument', 'code' : 9, 'codeName' : 'FailedToParse'

I checked some link in stackoverflow;
Spring data mongodb - The 'cursor' option is required
The 'cursor' option is required error coming from every aggregate

GIT URL
https://github.com/metabase/metabase/issues/6599
https://github.com/Automattic/mongoose/issues/4101

But I am not getting solution. Is it defect with updated version? Or we have to change some code? Thanks In Advance

Wow lots of formatting here. **Upgrade Mongoose**. This is not a MongoDB issue it's a "mongoose" issue. Mongoose versions prior to 5.x call a "legacy" mode of aggregate to return as a single BSON document, which is not compatible with the "default" action in MongoDB 3.6, which now expects a cursor. The code is fixed in recent mongoose releases. — Neil Lunn, May 07 '18 at 08:49
Huh? MongDB is 3.6 [**Mongoose is version 5.x**.](http://mongoosejs.com/) It's the **Mongoose** library that is the issue here. Even the [npm link](https://www.npmjs.com/package/mongoose) just to make it sink in. version 5.0.17 at time of writing. This is the only version of "mongoose" you should be using to talk to a MongoDB 3.6 server. — Neil Lunn, May 07 '18 at 11:13

score 1 · Accepted Answer · answered Jun 20 '19 at 14:01

I ran into this issue because I'm using keystone cms, and hence am forced to use their somewhat outdated dependencies, which in this case includes an older version of mongoose.

I was able to avoid this error you're getting and gain aggregate functionality with the following syntax (just replace the keystone.list code with your mongoose model):

keystone.list('Blurt').model.aggregate([
    {
        $lookup:{
            from: "users",       
            localField: "author.id",   
            foreignField: "_id", 
            as: "userImg"         
        }
    }
    ,
    {
        $unwind: '$userImg'
    },
    {
        $match: { 'author.id': {$ne: req.user._id}}
    },
    {
        $sample: {'size': 3}
    },
    {
        $project: {
            _id: '$userImg._id',
            name: '$userImg.name',
            smImg: '$userImg.smImg',
            text: 1,
            vote: 1,
            blurtDate: 1,
            blurtImg: 1
        }
    }
    ]).sort({ blurtDate: -1 })
    .cursor().exec()
    .toArray(function(err, data) {
        console.log(data);
        res.json(data);
    });

.toArray() was necessary for some reason; using a callback within the .exec() method returns an empty array no matter what never could figure out why. Using mongodb 4.0.4 and mongoose 4.7.8

How to resolve 'The 'cursor' option is required in MongoDB 3.6?

1 Answers1