HOW TO DESIGN GRAPHQL SCHEMAS, TYPES & RESOLVERS VISUALLY

GraphQL provides a strongly-typed query language for client-server communication. Unlike REST APIs with rigid endpoints, GraphQL allows client apps to request only the exact fields they need in a single round-trip.

1. ANATOMY OF GRAPHQL SDL TYPES

A standard GraphQL schema is built with object types, scalar types (ID, String, Int, Float, Boolean), and input objects:

type Product {
  id: ID!
  title: String!
  price: Float!
  inventory: Int!
  inStock: Boolean!
}

type Query {
  getProduct(id: ID!): Product
  listProducts(limit: Int = 20): [Product!]!
}

input CreateProductInput {
  title: String!
  price: Float!
  inventory: Int!
}

type Mutation {
  createProduct(input: CreateProductInput!): Product!
  deleteProduct(id: ID!): Boolean!
}

2. SCALABILITY BEST PRACTICES

• Always use non-null flags (!) deliberately: Distinguish between mandatory primary keys and optional metadata fields.
• Dedicated Input Types for Mutations: Never reuse output object types as mutation arguments.
• Pagination by Default: Always provide limit and offset (or cursor) arguments on list queries.