Exercise — Design an E-commerce Product Catalog Schema

What you'll walk away with

Explain the core ideas behind Exercise — Design an E-commerce Product Catalog Schema
Run the sample GraphQL query or code and verify its output
Apply the technique correctly to the Tutorial Platform and production scenarios

Build the mental model

This lesson is a design exercise, not runnable app code — it asks you to reapply schema and type-system ideas (lesson 3), relationships (lesson 8), enums/interfaces (lesson 9), input types (lesson 11), and pagination connections (lesson 13) to a fresh e-commerce domain. Deciding how to model relationships among products, categories, and reviews practices real, interview-style GraphQL schema-design skill.

Connect it to a real scenario

Mentally map the Tutorial Platform's course-catalog structure (tutorials/authors/categories) onto its e-commerce equivalent (products/sellers/categories) — model `Product↔Category` (many-to-many) the same way you modeled `Tutorial↔Category` earlier. Model reviews the way you modeled comments, adding a `rating: Int!` field.

This is a design exercise: write SDL, not runnable code
Product-Category is a many-to-many relationship
Model Review by extending the Comment pattern

Try the working example

graphql

type Product {
  id: ID!
  name: String!
  priceCents: Int!
  categories: [Category!]!
  reviews: [Review!]!
}

type Category {
  id: ID!
  name: String!
  products: [Product!]!
}

type Review {
  id: ID!
  rating: Int!
  body: String
  author: String!
}

# TODO: add Query fields for browsing products by category
# TODO: add a CreateReviewInput and a createReview mutation

You should see

You can design and write a schema modeling relationships among products, categories, and reviews.

5-minute try-it

Complete the starter schema above with a `Query` type (products list, product by id, category by id) and a `CreateReviewInput` plus `createReview` mutation. Also try applying the pagination connection pattern to the `products` list field.

One important caution

Designing `Product.category: Category!` as a single non-null field cannot express the real e-commerce requirement that a product belongs to many categories — use a list field when the relationship is many-to-many.

GraphQL — Schemas and Types — GraphQL

Easy traps

Designing `Product.category: Category!` as a single non-null field cannot express the real e-commerce requirement that a product belongs to many categories — use a list field when the relationship is many-to-many.
Validate sample queries and mutations on a local or test server with recoverable data before applying them to production.

Exercise

You'll know it worked when: You can design and write a schema modeling relationships among products, categories, and reviews.