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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.
With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.
Try a 14-Day Free Trial of Orkes Conductor today.
Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.
With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.
Try a 14-Day Free Trial of Orkes Conductor today.
Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.
Get started with mocking and improve your application tests using our Mockito guide:
Spring 5 added support for reactive programming with the Spring WebFlux module, which has been improved upon ever since. Get started with the Reactor project basics and reactive programming in Spring Boot:
Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.
But these can also be overused and fall into some common pitfalls.
To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:
Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:
Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.
I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.
You can explore the course here:
Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.
With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.
Try a 14-Day Free Trial of Orkes Conductor today.
Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.
Get started with Spring Data JPA through the guided reference course:
Refactor Java code safely — and automatically — with OpenRewrite.
Refactoring big codebases by hand is slow, risky, and easy to put off. That’s where OpenRewrite comes in. The open-source framework for large-scale, automated code transformations helps teams modernize safely and consistently.
Each month, the creators and maintainers of OpenRewrite at Moderne run live, hands-on training sessions — one for newcomers and one for experienced users. You’ll see how recipes work, how to apply them across projects, and how to modernize code with confidence.
Join the next session, bring your questions, and learn how to automate the kind of work that usually eats your sprint time.
Regression testing is an important step in the release process, to ensure that new code doesn't break the existing functionality. As the codebase evolves, we want to run these tests frequently to help catch any issues early on.
The best way to ensure these tests run frequently on an automated basis is, of course, to include them in the CI/CD pipeline. This way, the regression tests will execute automatically whenever we commit code to the repository.
In this tutorial, we'll see how to create regression tests using Selenium, and then include them in our pipeline using GitHub Actions:, to be run on the LambdaTest cloud grid:
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1. Introduction
In this tutorial, we’ll see how we can create a new API inside a JHipster application. We’ll then integrate that API into the front-end display.
2. Sample Application
For this tutorial, we’ll be using a simple book store application.
The book store is built as a monolith. It uses Angular for the front-end and has a single entity named book with the following fields:
- Title
- Author
- Published Data
- Price
- Quantity
JHipster automatically generates APIs and front-end views that provide simple operations for a book: view, create, edit, and delete.
For this tutorial, we’ll add an API that lets a user purchase a book, along with a button on the front-end that calls the new API.
We’ll focus just on the API and front-end aspects of purchasing. We won’t perform any payment processing and only minimal validation.
3. Spring Boot Changes
JHipster provides a generator for creating new controllers. However, for this tutorial, we’ll manually create the API and associated code.
3.1. Resource Class
The first step is to update the generated BookResource class. We add the new endpoint that the front-end code will call:
@GetMapping("/books/purchase/{id}")
public ResponseEntity<BookDTO> purchase(@PathVariable Long id) {
Optional<BookDTO> bookDTO = bookService.purchase(id);
return ResponseUtil.wrapOrNotFound(bookDTO);
}This creates a new API endpoint located at /books/purchase/{id}. The only input is the book’s id, and we return a BookDTO that will reflect the new stock level after purchasing.
3.2. Service Interface and Class
Now, we need to update the BookService interface to include a new purchase method:
Optional<BookDTO> purchase(Long id);Then, we need to implement the new method in the BookServiceImpl class:
@Override
public Optional<BookDTO> purchase(Long id) {
Optional<BookDTO> bookDTO = findOne(id);
if (bookDTO.isPresent()) {
int quantity = bookDTO.get().getQuantity();
if (quantity > 0) {
bookDTO.get().setQuantity(quantity - 1);
Book book = bookMapper.toEntity(bookDTO.get());
book = bookRepository.save(book);
return bookDTO;
}
else {
throw new BadRequestAlertException("Book is not in stock", "book", "notinstock");
}
}
return Optional.empty();
}Let’s look at what is happening in this code. First, we look up the book by its id to confirm it exists. If it doesn’t, we return an empty Optional.
If it does exist, then we ensure it has a stock level greater than zero. Otherwise, we throw a BadRequestAlertException. While this exception is normally only used in the REST layer of JHipster, we’re using it here to demonstrate how to return useful error messages to the front-end.
Otherwise, if the stock is greater than zero, then we reduce it by one, save it to the repository, and return the updated DTO.
3.3. Security Configuration
The final change required is in the SecurityConfiguration class:
.antMatchers("/api/books/purchase/**").authenticated()This ensures calls to our new API are only allowed by authenticated users.
4. Front-End Changes
Now let’s focus on the front-end changes. JHipster creates a view for displaying a single book, and that’s where we’ll add our new purchase button.
4.1. Service Class
First, we need to add a new method to the existing book.service.ts file. This file already contains the methods for manipulating book objects, so it’s a good place to add the logic for our new API:
purchase(id: number): Observable<EntityResponseType> {
return this.http
.get<IBook>(`${this.resourceUrl}/purchase/${id}`, { observe: 'response' })
.pipe(map((res: EntityResponseType) => this.convertDateFromServer(res)));
}4.2. Component
Then, we need to update the component code in book.component.ts. We’ll create a function that calls the new method in the Angular book service and then listens for the response back from the server:
purchase(id: number) {
this.bookService.purchase(id).subscribe(
(res: HttpResponse<IBook>) => {
this.book = res.body;
},
(res: HttpErrorResponse) => console.log(res.message)
);
}4.3. View
Finally, we can add a button to the book view that calls the new purchase method in the component:
<button type="button"
class="btn btn-primary"
(click)="purchase(book.id)">
<span>Purchase</span>
</button>The image below shows the updated view on the front-end:
Clicking the new Purchase button will result in a call to our new API, and the front-end will automatically update with the new stock status (or display an error if something went wrong).
5. Conclusion
In this tutorial, we have seen how to create custom APIs in JHipster, and integrate them into the front-end.
We started by adding the API and business logic into Spring Boot. Then, we modified the front-end code to utilize the new API and display the results. With just a little effort we were able to add new functionality on top of the existing CRUD operations that JHipster automatically generates.
The code backing this article is available on GitHub. Once you're logged in as a Baeldung Pro Member, start learning and coding on the project.
