GraphQL Schema Design Guide
Design effective GraphQL schemas with best practices for naming conventions, type relationships, nullability decisions, and common patterns. Use the schema generator above to prototype your types from real data.
JSON to GraphQL Schema Generator
Generate GraphQL schema definitions from JSON data. Automatically infers types, detects IDs, dates, and nested objects. Optionally generates Query and Mutation types.
About JSON to GraphQL Schema
- Infers GraphQL scalar types (String, Int, Float, Boolean, ID) from JSON values automatically.
- Detects UUIDs and ID-like fields →
ID, dates →DateTime/Datecustom scalars. - Nested objects become separate GraphQL types. Arrays of objects are merged for complete field coverage.
- Optionally generates Query type (get by ID, list all) and Mutation type (create, update, delete) with input types.
- Download the schema as a
.graphqlfile ready for your server. - Everything runs in your browser — no data is sent over the network.
Naming conventions
GraphQL types use PascalCase (User, BlogPost). Fields use camelCase (firstName, createdAt). Enum values use SCREAMING_SNAKE_CASE (PUBLISHED, DRAFT). Input types are conventionally suffixed with 'Input' (CreateUserInput). These conventions are not enforced by the spec but are widely adopted across the ecosystem.
Designing for relationships
Unlike REST, GraphQL schemas explicitly model relationships between types. A User type might have a posts: [Post!]! field, and a Post type might have an author: User! field. This bidirectional relationship lets clients query in either direction. Use connection types (edges/nodes pattern) for paginated lists following the Relay specification.
Nullability decisions
Making fields non-null (!) is a contract with your clients — you guarantee the field will always have a value. Be conservative: start with nullable fields and only add ! when you are certain the field will never be null. Non-null fields that return null cause the entire parent object to be nullified, which can cascade up the query tree.
Frequently Asked Questions
Should I use interfaces or unions in GraphQL?
Use interfaces when types share common fields (e.g., Node interface with an id field). Use unions when types are completely different but can appear in the same list (e.g., SearchResult = User | Post | Comment). Interfaces require implementing types to include all interface fields.
How should I handle errors in GraphQL schemas?
Two common patterns: (1) Use the top-level errors array for unexpected failures. (2) Model expected errors as union types in your schema (e.g., CreateUserResult = User | ValidationError | DuplicateEmailError). The union approach gives clients type-safe error handling.
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