Mongoose .populate() is not working with node.js app

Working with Data Node.js Frameworks
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1

First post here, so hello to everyone!

I’m having trouble with mongoose populate because it’s apparently doing nothing. I’m going straight to the code.

Here are my models:

Space

const spaceSchema = Schema(
	{
		user: {
			type: Schema.Types.ObjectId,
			required: true,
			ref: "User",
		},
		name: {
			type: String,
			required: true,
		},
		days: [{ type: Schema.Types.ObjectId, refPath: "Day" }],
	},
	{
		versionKey: false,
	        timestamps: true 
        },
);

const Space = mongoose.model("Space", spaceSchema);

module.exports = Space;

Day

const daySchema = Schema(
	{
		space: { type: Schema.Types.ObjectId, refPath: "Space" },
		date: {
			type: String,
			required: true,
		},
		water: {
			type: Boolean,
		},
		fertilizer: {
			type: Boolean,
		},
		transplant: {
			type: Boolean,
		},
		comment: {
			type: String,
		},
	},
	{
		versionKey: false,
	        timestamps: true 
        },
);

const Day = mongoose.model("Day", daySchema);

module.exports = Day;

And the part of the controller where I have the getSpace route (/api/spaces/:id):

const getSpace = asyncHandler(async (req, res) => {
	const space = await Space.findById(req.params.id).populate("days");
	res.status(200).json(space);
});

And this is the result I get:

{
    "_id": "63580115978dbf8f2f5a7a50",
    "user": "63501ab84613855834daa4ef",
    "name": "spaceName",
    "days": []
}

I tried many things, but all the results were the same.

Let me know if you need any other part of the code.

Thank you all :smiley:

I expect the result to look something like this

    "space": {
        "_id": "63580115978dbf8f2f5a7a50",
        "user": "63501ab84613855834daa4ef",
        "name": "spaceName",
        "days": [
            {
                "_id": "63581af565aed8cad3210046",
                "space": "63580115978dbf8f2f5a7a50",
                "date": "29/10/2022",
                "water": true,
                "fertilizer": true,
                "transplant": false,
                "comment": "This is a comment.",
                "createdAt": ...,
                "updatedAt": ...
            },
            {
                "_id": "63581af565aed8cad3210046",
                "space": "63580115978dbf8f2f5a7a50",
                "date": "29/10/2022",
                "water": false,
                "fertilizer": false,
                "transplant": true,
                "comment": "This is a comment.",
                "createdAt": ...,
                "updatedAt": ...
            }
        ]
    }
2

refPath doesn’t mean, what you might think it does. What you need here is a simple ref.
So, just change refPath to ref in your schemas and your example should be working as you expect.

But, there is a second thing. You have redundant references: days refer to spaces and spaces to days. Generally you don’t need to refer to each other in both ways (unless in your specific use case you do). For many-to-one or many-to-many relations there are Populate Virtuals. You can read up on it in the Mongoose documentation.

So I would get rid of the days field in the Space schema, and replace it with a populate virtual:

const spaceSchema = Schema(
	{
		user: {
			type: Schema.Types.ObjectId,
			required: true,
			ref: "User",
		},
		name: {
			type: String,
			required: true,
		},
	},
	{
		versionKey: false,
		timestamps: true,
	},
);

spaceSchema.virtual('days', {
	ref: 'Day',
	localField: '_id',
	foreignField: 'space',
});

const Space = mongoose.model("Space", spaceSchema);

module.exports = Space;
1 Like
3

Hi pepkin88,

Thanks for your answer :smiley:

I tried this populate virtual, but it’s returning me this now:

{
    "_id": "63580b9f6d2b99c33923c876",
    "user": "63501ab84613855834daa4ef",
    "name": "balco",
    "createdAt": "2022-10-25T16:15:27.304Z",
    "updatedAt": "2022-10-25T16:15:27.304Z"
}

There are no days in my answer :sweat_smile:

I also changed refPath to ref but no luck.

I also tried another way (I’m not so wure if it’s better or worse than using populate) but I got the answer I wanted.
I used this:

const getSpace = asyncHandler(async (req, res) => {
	const space = await Space.findById(req.params.spaceId);
	space.days = await Day.find({ space: req.params.spaceId });
	res.status(200).json(space);
});

And answer is what I wanted :partying_face:

Thanks for your answer anyway :mechanical_arm:

1 Like
4

I’m using the latest version of mongodb and mongoose and populate() is working fine…

mongodb: 6.3.0
mongoose:8.0.1

This is from my app.js file

Screenshot 2023-11-22 103752
Screenshot 2023-11-22 1037521128×438 48.7 KB

This is from my task model file

const task_schema = new mongoose.Schema({
    name:{
        type:String,
        trim:true,
        required:true
    },
    desc:{
        type:String,
        trim:true,
        required:true
    },
    completed:{
        type:Boolean,
        trim:true,
        default:false
    },
    owner:{
        type: mongoose.Schema.Types.ObjectId,
        required:true,
        ref:'user_collection'
    }
});

This is from my task router file

//creating a task...
router.post('/tasks',auth, async (req, res) => {
    const task  = task_model({
        ...req.body,
        owner: req.user._id
    })
    
    console.log(`Url tasks is hit with request....`);
    try {
        const savedTask = await task.save();
        res.send(savedTask);
    } catch (err) {
        res.send(500).send(err);
    }

})

This from auth middleware file

const auth = async (req, res, next) => {
    try {
        const token = req.header('Authorization').replace('Bearer ','');
        const decoded = jwt.verify(token,'secret123');
        const user = await user_model.findOne({_id: decoded._id,'tokens.token':token});

        if(!user){
            throw new Error();
        }
        
        req.token = token;
        req.user = user;
        next();
    } catch (err) {
        res.status(401).send(`You are not authorized ${err}`);
    }
}

Hope it helps…