graphql-schema-design

# GraphQL Schema Design Skill

> Architect scalable, maintainable GraphQL APIs

## Overview

Learn industry-standard patterns for designing GraphQL schemas that scale. Covers naming conventions, pagination, error handling, and schema evolution.

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## Quick Reference

| Pattern | When to Use | Example |
|---------|-------------|---------|
| Connection | Paginated lists | `users: UserConnection!` |
| Payload | Mutation results | `CreateUserPayload` |
| Input | Mutation args | `CreateUserInput` |
| Interface | Shared fields | `interface Node { id: ID! }` |
| Union | Multiple types | `SearchResult = User \| Post` |

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## Core Patterns

### 1. Naming Conventions

```graphql
# Types: PascalCase
type User { }
type UserProfile { }

# Fields: camelCase
type User {
  firstName: String!
  lastName: String!
  createdAt: DateTime!
  isActive: Boolean!      # Boolean prefix: is, has, can
}

# Queries: noun (singular/plural)
type Query {
  user(id: ID!): User           # Singular
  users: UserConnection!         # Plural
}

# Mutations: verb + noun
type Mutation {
  createUser(input: CreateUserInput!): CreateUserPayload!
  updateUser(id: ID!, input: UpdateUserInput!): UpdateUserPayload!
  deleteUser(id: ID!): DeleteUserPayload!

  # Actions
  sendEmail(input: SendEmailInput!): SendEmailPayload!
  publishPost(id: ID!): PublishPostPayload!
}

# Inputs: [Action][Type]Input
input CreateUserInput { }
input UpdateUserInput { }
input UserFilterInput { }

# Payloads: [Action][Type]Payload
type CreateUserPayload { }
type UpdateUserPayload { }
```

### 2. Relay-Style Pagination

```graphql
# Connection pattern
type Query {
  users(
    first: Int
    after: String
    last: Int
    before: String
    filter: UserFilter
  ): UserConnection!
}

type UserConnection {
  edges: [UserEdge!]!
  pageInfo: PageInfo!
  totalCount: Int!
}

type UserEdge {
  node: User!
  cursor: String!
}

type PageInfo {
  hasNextPage: Boolean!
  hasPreviousPage: Boolean!
  startCursor: String
  endCursor: Stri