How to populate an ObjectId object within an array in Mongoose?

Question

First of all, I found a lot of answers about that problem in StackOverflow However, none of them worked on my problem.

I have an userSchema like that:

const UserSchema = new Schema({
  userName: {
    type: String,
    required: true,
  },
  userSurname: {
    type: String,
    required: true,
  },
  userEmail: {
    type: String,
    unique: true,
    required: true,
  },
  userPassword: {
    type: String,
    required: true,
  },
  userRole: {
    type: String,
    enum: ['müşteri', 'admin'],
    default: 'müşteri',
  },
  userCart: [
    {
      productId: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Product',
      },
     quantity: Number,
     price:Number,
      
    },
  ],
});

I wanted to populate the productId in array of userCart so I can reach:

const ProductSchema = new Schema({
  productName: {
    type: String,
    unique: true,
    required: true,
  },
  productBrand: {
    type: String,
    required: true,
  },
  productPrice: {
    type: String,
    required: true,
  },
  productPhoto: {
    type: String,
    required: true,
  },
  productQuantity: {
    type: Number,
    required: true,
  },
  slug: {
    type: String,
    unique: true,
  },
  category: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Category',
  },
});

those fields.

I tried

const products = await User.findById(req.session.userID).populate('userCart');

and

const products = await User.findById(req.session.userID).populate('userCart.productId');

and I thought it might be because of findById so instead of findById I tried findOne and that one also didn't work.

And after doing that I tried to reach in ejs file like that but it shows nothing.

<% for(let i =0; i< products.userCart.length; i++) { %>
        <div>
            <%= products.userCart[i].productName %>
        </div>
        
        <% } %>

Any help is appreciated, thanks in advance.

score 0 · Answer 1 · answered Dec 30 '22 at 15:00

0

if you want to populate the schema, you have to execute a preQuery on that schema when you execute "find" query.

First of all I think you have to update your UserSchema. Update this for your userCart in the userSchema definition: (try to avoid nesting.)

userCart: {
     type: mongoose.Schema.Types.ObjectId,
     ref: 'Product',
    },

Then, Add this Middleware query to your userSchema:

//QUERY MIDDLEWARE
UserSchema.pre(/^find/, (next) => {
    this.populate({
        path:"userCart",
    });

    next();
});

This code will be executed and would populate your data for that productId on every "find" query for your userSchema.

Let me know if you have any issues or questions.

answered Dec 30 '22 at 15:00

Dimitar Stojanovski

141
1
6

But I need that "quantity: Number" field. This field came in an input that the user filled. Also, userCart must be an array because it might have more than one Product. @Dimitar Stojanovski – Alim Gölcük Dec 30 '22 at 15:07
Now, ı can't log in when ı change the code to that :) @DimitarStojanovski – Alim Gölcük Dec 30 '22 at 15:30
That price field should be in your Product Schema for sure. – Dimitar Stojanovski Dec 30 '22 at 15:34
1

Maybe it's better to have another Schema for every Cart. Please check this example. It's written in NestJs but it is the same issue. https://blog.logrocket.com/how-build-ecommerce-app-nestjs/ @AlimGölcük – Dimitar Stojanovski Dec 30 '22 at 15:41
I will, thank you for your efforts @DimitarStojanovski – Alim Gölcük Dec 30 '22 at 15:44

How to populate an ObjectId object within an array in Mongoose?

1 Answers1