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

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

Mutation Structure

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

Subscription Structure

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

# 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

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

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

Directives

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

# 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

# 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

# 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

// 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

graphql-operations