OpenApi Generated Code Example

Backend: A SpringBoot application configured to generate both Java code and TypeScript client code from an OpenApi specification.

Frontend: A Next.js using the generated client to call the backend API.

Generation

The openapi spec is defined in backend/src/main/resources/api/books.yaml.

Maven OpenAPI Generator is configured in pom.xml to generate the following:

Java

• Controller Interface, which is implemented in BooksController.
• DTOs including validation annotations.
• This generated code can be found in backend/target/generated-sources/openapi/java
• Postman collection backend/postman

Note: This can be configured to build and publish a separate jar rather than local files (e.g. if required by another Java client service).

TypeScript

• A default client that can be used to call the API. Currently configured to use fetch, but other generators are available for axios etc.
• DTOs
• This generated code can be found in frontend/lib/generated/openapi and is consumed in frontend/src/app/page.tsx

Note: This should be configured to publish an npm library ideally, but working with local files for the purposes of this demo.

Run

Pre-requisites

• Maven
• Java 17
• node >= 18.17.0

Backend

From the backend directory:

# Build and publish generated code
mvn clean install

# Run the app
mvn spring-boot:run

Testing

See BooksControllerIT.java for a demonstrative integration test.

Frontend

From the frontend directory:

# Install dependencies
npm install

# Run the app
npm run dev