GraphQL Operations Guide

This guide covers best practices for writing GraphQL operations (queries, mutations, subscriptions) as a client developer. Well-written operations are efficient, type-safe, and maintainable.

Operation Basics

Query Structure

graphql

query GetUser($id: ID!) {
  user(id: $id) {
    id
    name
    email
  }
}

Mutation Structure

graphql

mutation CreatePost($input: CreatePostInput!) {
  createPost(input: $input) {
    id
    title
    createdAt
  }
}

Subscription Structure

graphql

subscription OnMessageReceived($channelId: ID!) {
  messageReceived(channelId: $channelId) {
    id
    content
    sender {
      id
      name
    }
  }
}

Quick Reference

Operation Naming

Pattern	Example
Query	`GetUser`, `ListPosts`, `SearchProducts`
Mutation	`CreateUser`, `UpdatePost`, `DeleteComment`
Subscription	`OnMessageReceived`, `OnUserStatusChanged`

Variable Syntax

graphql

# Required variable
query GetUser($id: ID!) { ... }

# Optional variable with default
query ListPosts($first: Int = 20) { ... }

# Multiple variables
query SearchPosts($query: String!, $status: PostStatus, $first: Int = 10) { ... }

Fragment Syntax

graphql

# Define fragment
fragment UserBasicInfo on User {
  id
  name
  avatarUrl
}

# Use fragment
query GetUser($id: ID!) {
  user(id: $id) {
    ...UserBasicInfo
    email
  }
}

Directives

graphql

query GetUser($id: ID!, $includeEmail: Boolean!) {
  user(id: $id) {
    id
    name
    email @include(if: $includeEmail)
  }
}

query GetPosts($skipDrafts: Boolean!) {
  posts {
    id
    title
    draft @skip(if: $skipDrafts)
  }
}

Key Principles

1. Request Only What You Need

graphql

# Good: Specific fields
query GetUserName($id: ID!) {
  user(id: $id) {
    id
    name
  }
}

# Avoid: Over-fetching
query GetUser($id: ID!) {
  user(id: $id) {
    id
    name
    email
    bio
    posts { id title content comments { id } }
    followers { id name }
    # ... many unused fields
  }
}

2. Name All Operations

graphql

# Good: Named operation
query GetUserPosts($userId: ID!) {
  user(id: $userId) {
    posts { id title }
  }
}

# Avoid: Anonymous operation
query {
  user(id: "123") {
    posts { id title }
  }
}

3. Use Variables, Not Inline Values

graphql

# Good: Variables
query GetUser($id: ID!) {
  user(id: $id) {
    id
    name
  }
}

# Avoid: Hardcoded values
query {
  user(id: "123") {
    id
    name
  }
}

4. Colocate Fragments with Components

tsx

// UserAvatar.tsx
export const USER_AVATAR_FRAGMENT = gql`
  fragment UserAvatar on User {
    id
    name
    avatarUrl
  }
`;

function UserAvatar({ user }) {
  return <img src={user.avatarUrl} alt={user.name} />;
}

Reference Files

Detailed documentation for specific topics:

•Queries - Query patterns and optimization
•Mutations - Mutation patterns and error handling
•Fragments - Fragment organization and reuse
•Variables - Variable usage and types
•Tooling - Code generation and linting

Ground Rules

•ALWAYS name your operations (no anonymous queries/mutations)
•ALWAYS use variables for dynamic values
•ALWAYS request only the fields you need
•ALWAYS include id field for cacheable types
•NEVER hardcode values in operations
•NEVER duplicate field selections across files
•PREFER fragments for reusable field selections
•PREFER colocating fragments with components
•USE descriptive operation names that reflect purpose
•USE @include/@skip for conditional fields