tools-only GraphQL Schema Design
Object Types
"""
User account with authentication and profile information.
All users must have a unique email address.
"""
type User {
"Unique user identifier"
id: ID!
"User's email address (unique)"
email: String!
"Display name (optional)"
username: String
"Account creation timestamp"
createdAt: DateTime!
"User's posts (paginated)"
posts(first: Int = 10, after: String): PostConnection!
"User's profile (nullable if not completed)"
profile: Profile
}
type Profile {
id: ID!
bio: String
avatarUrl: URL
website: URL
location: String
}
type Post {
id: ID!
title: String!
content: String!
author: User!
publishedAt: DateTime
status: PostStatus!
tags: [Tag!]!
comments(first: Int, after: String): CommentConnection!
}
Interfaces
"""
Common interface for all content that can be timestamped
"""
interface Timestamped {
id: ID!
createdAt: DateTime!
updatedAt: DateTime!
}
"""
Interface for searchable content
"""
interface Searchable {
id: ID!
title: String!
description: String
}
type Article implements Timestamped & Searchable {
id: ID!
title: String!
description: String
content: String!
createdAt: DateTime!
updatedAt: DateTime!
author: User!
}
type Video implements Timestamped & Searchable {
id: ID!
title: String!
description: String
url: URL!
duration: Int!
createdAt: DateTime!
updatedAt: DateTime!
uploader: User!
}
# Query returning interface
type Query {
search(query: String!): [Searchable!]!
}
Union Types
"""
Result of a content search - can be Article, Video, or Podcast
"""
union SearchResult = Article | Video | Podcast
"""
Notification types that users can receive
"""
union Notification = CommentNotification | LikeNotification | FollowNotification
type CommentNotification {
id: ID!
comment: Comment!
post: Post!
createdAt: DateTime!
}
type LikeNotification {
id: ID!
liker: User!
post: Post!
createdAt: DateTime!
}
type Query {
searchContent(query: String!): [SearchResult!]!
notifications(first: Int): [Notification!]!
}
Enums
"""
Post publication status
"""
enum PostStatus {
DRAFT
PUBLISHED
ARCHIVED
DELETED
}
"""
User role for authorization
"""
enum UserRole {
ADMIN
MODERATOR
USER
GUEST
}
"""
Sort direction for queries
"""
enum SortOrder {
ASC
DESC
}
type Query {
posts(
status: PostStatus
orderBy: SortOrder = DESC
): [Post!]!
}
Input Types
"""
Input for creating a new user
"""
input CreateUserInput {
email: String!
password: String!
username: String
profile: ProfileInput
}
input ProfileInput {
bio: String
avatarUrl: URL
website: URL
location: String
}
"""
Input for updating a post
"""
input UpdatePostInput {
title: String
content: String
status: PostStatus
tags: [ID!]
}
"""
Pagination and filtering input
"""
input PostFilterInput {
status: PostStatus
authorId: ID
tags: [String!]
search: String
createdAfter: DateTime
createdBefore: DateTime
}
type Mutation {
createUser(input: CreateUserInput!): User!
updatePost(id: ID!, input: UpdatePostInput!): Post!
}
type Query {
posts(filter: PostFilterInput, first: Int, after: String): PostConnection!
}
Custom Scalars
"""
ISO 8601 date-time string
"""
scalar DateTime
"""
Valid URL string
"""
scalar URL
"""
Valid email address
"""
scalar Email
"""
JSON object
"""
scalar JSON
"""
Positive integer
"""
scalar PositiveInt
type User {
id: ID!
email: Email!
createdAt: DateTime!
website: URL
metadata: JSON
age: PositiveInt
}
Pagination Patterns
"""
Cursor-based pagination (Relay specification)
"""
type PostConnection {
edges: [PostEdge!]!
pageInfo: PageInfo!
totalCount: Int!
}
type PostEdge {
node: Post!
cursor: String!
}
type PageInfo {
hasNextPage: Boolean!
hasPreviousPage: Boolean!
startCursor: String
endCursor: String
}
type Query {
posts(
first: Int
after: String
last: Int
before: String
): PostConnection!
}
Nullable vs Non-Nullable Best Practices
type User {
# Non-nullable: guaranteed to exist
id: ID!
email: String!
createdAt: DateTime!
# Nullable: optional or may not exist yet
username: String
bio: String
avatarUrl: URL
# Non-null list of nullable items
# List always exists but can be empty, items can be null
tags: [String]!
# Non-null list of non-null items
# List always exists, all items guaranteed non-null
roles: [UserRole!]!
# Nullable list of non-null items
# List may be null, but if exists, all items non-null
posts: [Post!]
}
type Query {
# Non-null: query always returns result (empty list if none)
users: [User!]!
# Nullable: may return null if not found
user(id: ID!): User
# Non-null: guaranteed to return result or error
currentUser: User!
}
Field Deprecation
type User {
id: ID!
email: String!
# Deprecated field with migration path
name: String @deprecated(reason: "Use 'username' instead")
username: String
# Deprecated with specific date
legacyId: String @deprecated(
reason: "Migrating to UUID. Will be removed 2025-06-01"
)
}
Schema Documentation
"""
User represents an authenticated account in the system.
Users can create posts, comments, and interact with content.
Example query:
query GetUser { user(id: "123") { email username posts(first: 10) { edges { node { title } } } } }
"""
type User {
"Unique identifier for the user"
id: ID!
"Email address (must be unique across all users)"
email: String!
"Optional display name (defaults to email if not set)"
username: String
}
Design Principles
- Nullable Fields: Make fields nullable by default unless guaranteed to exist
- List Fields: Use
[Type!]!for lists that always exist with non-null items - Documentation: Document all types and fields with descriptions
- Naming: Use camelCase for fields, PascalCase for types
- Interfaces: Use interfaces for shared fields across types
- Unions: Use unions for polymorphic return types
- Input Types: Create separate input types for mutations
- Scalars: Use custom scalars for domain-specific types
- Deprecation: Mark deprecated fields, provide migration path
- Examples: Include example queries in documentation