codegen-over-complex-types

Install openapi-typescript as a dev dependency and run npx openapi-typescript schema.yaml -o src/api-types.ts. The generated file contains typed paths, request bodies, and response schemas that stay in sync with your API definition.

Choose code generation when types mirror an external source of truth like an API or database, when type-level logic exceeds comfortable complexity, or when synchronization matters. Use type-level code for simple transformations of your own internal types.

Install @graphql-codegen/cli with the typescript and typescript-operations plugins, then configure a codegen.yml pointing at your schema file. Running npx graphql-codegen produces typed queries, mutations, and schema types.

Add generation commands to your package.json build and predev scripts, then add a CI step that regenerates types and runs git diff --exit-code on the output file. The build fails whenever committed types drift from the schema.

Yes, use a hybrid approach: import generated base types from the schema, extend them with application-specific fields via interfaces, and derive variants with utility types like Omit and Partial for inputs and updates.