Category and Subcategory in mongodb using mongoose

Question

I'm creating an ecommerce website using nodejs. Ideally, the product will have a category and subcategory. But what I'm creating should be used with any type of ecommerce website, and therefore, the subcategory field might not be needed.

In the product schema I added the subcategory field, which is related to the subcategory document. And the subcategory document is related to the category document.

My question is, how can a product be added in the database without a subcategory?

Category schema:

const categorySchema = mongoose.Schema({
    name: {
        type: String,
        required: true,
    }
})

module.exports = mongoose.model('Category', categorySchema);

Subcategory schema:

const subCategorySchema = mongoose.Schema({
    name: {
        type: String,
        required: true,
    },
    Category: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'Category',
        required:true
    },
})

module.exports = mongoose.model('SubCategory', subCategorySchema);

Product schema:

const productSchema = mongoose.Schema({
    name: {
        type: String,
        required: true,
    },
    description: {
        type: String,
        required: true
    },
    price : {
        type: Number,
        default:0
    },
    SubCategory: {
        type: mongoose.Schema.Types.ObjectId,
        ref: 'SubCategory',
        required:true
    },
    countInStock: {
        type: Number,
        required: true,
        min: 0,
        max: 255
    },
})


module.exports = mongoose.model('Product', productSchema);

Thanks in advance...

Answer 1

I'm afraid you're going to have to have a required Category field in your ProductSchema and a non-required SubCategory field. This way, you'll make sure that all your products have, at least, a Category, and allow for a SubCategory to be added:

const productSchema = mongoose.Schema({
  name: {
      type: String,
      required: true,
  },
  description: {
      type: String,
      required: true
  },
  price : {
      type: Number,
      default:0
  },
  Category: {
    type: mongoose.Schema.Types.ObjectId,
    ref: 'Category',
    required: true
  },
  SubCategory: {
      type: mongoose.Schema.Types.ObjectId,
      ref: 'SubCategory',
      required: false
  },
  countInStock: {
      type: Number,
      required: true,
      min: 0,
      max: 255
  },
})

If you want to make sure that the hierarchy of the category and subcategory, you can always add some middleware validation on your pre-save:

productSchema.pre('save', async function (next) {
  if (this.SubCategory) {
    try {
      const check = await SubCategory.findById(this.SubCategory);
      if (!check || JSON.stringify(check.Category) !== JSON.stringify(this.Category)) {
        throw new Error('Check your Category and/or SubCategory');
      }
    } catch (error) {
      throw error;
    }
  }
  next();
});