The Quarkus Conundrum: Unraveling the Mystery of CDI Failing to Find ApplicationScoped Beans during quarkus-maven-plugin

Are you a Quarkus enthusiast who’s hit a roadblock while trying to inject an @ApplicationScoped bean? Do you find yourself scratching your head, wondering why CDI (Contexts and Dependency Injection) refuses to acknowledge the existence of your carefully crafted bean? Fear not, dear reader, for you’re about to embark on a thrilling adventure that will unravel the tangled threads of this enigmatic issue.

What’s the Big Deal About CDI and ApplicationScoped Beans?

Before we dive into the solution, let’s take a step back and appreciate the beauty of CDI and @ApplicationScoped beans. CDI, as you know, is a fundamental component of Java EE (Enterprise Edition) that enables dependency injection, making your code more modular, flexible, and testable. @ApplicationScoped beans, on the other hand, are a type of bean that’s created once during the application’s lifetime and is shared across all requests.

The synergy between CDI and @ApplicationScoped beans is what makes Quarkus so powerful. By injecting an @ApplicationScoped bean, you can share business logic, caching, or other application-wide concerns across your application, resulting in a more efficient and scalable architecture.

The quarkus-maven-plugin Conundrum

So, what’s the hitch? When using the quarkus-maven-plugin, CDI might fail to find your @ApplicationScoped bean, leaving you with a cryptic error message and a sense of frustration. This issue can manifest in various ways, such as:

• javax.enterprise.inject.UnsatisfiedResolutionException: Unable to find instance of [your.bean.Class]
• org.jboss.weld.exceptions.DeploymentException: WELD-001408: Unsatisfied dependencies for type [your.bean.Class]

Don’t worry; we’ll get to the bottom of this riddle together.

Step 1: Verify Your Bean’s Annotated Correctly

Before we proceed, ensure that your @ApplicationScoped bean is annotated correctly:

@ApplicationScoped
public class MyBean {
  // ...
}

If you’re using a bean that’s not annotated with @ApplicationScoped, CDI won’t recognize it as an application-scoped bean. Make sure to add the annotation to your bean class.

Step 2: Check Your Maven Configuration

In your Maven project, ensure that you’ve correctly configured the quarkus-maven-plugin to include the necessary dependencies:

<build>
  <plugins>
    <plugin>
      <groupId>io.quarkus</groupId>
      <artifactId>quarkus-maven-plugin</artifactId>
      <version>${quarkus.version}</version>
      <executions>
        <execution>
          <goals>
            <goal>build</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

This configuration tells Maven to include the Quarkus dependencies required for runtime.

Step 3: Update Your POM File

In your Maven project’s pom.xml file, ensure that you’ve added the following dependencies:

<dependencies>
  <dependency>
    <groupId>io.quarkus</groupId>
    <artifactId>quarkus-arc</artifactId>
  </dependency>
  <dependency>
    <groupId>io.quarkus</groupId>
    <artifactId>quarkus-weld</dependency>
</dependencies>

The quarkus-arc and quarkus-weld dependencies are essential for CDI to work correctly.

Step 4: Enable CDI in Your Quarkus Application

In your Quarkus application, ensure that you’ve enabled CDI by adding the following configuration to your application.properties file:

quarkus.arc.enabled=true

This configuration tells Quarkus to enable CDI, allowing your application to use CDI features.

Step 5: Verify Your Bean’s Package

Make sure that your @ApplicationScoped bean is located in a package that’s scanned by CDI. By default, Quarkus scans the package containing the main application class (e.g., com.example.MyApp). If your bean is located in a different package, you’ll need to add it to the CDI scan:

@QuarkusApplication
public class MyApp extends QuarkusApplication {

  @Inject
  private MyBean myBean;

  // ...
}

In this example, we’re using the @QuarkusApplication annotation to enable CDI scanning for the com.example package, which contains our MyBean class.

Step 6: Review Your Bean’s Construction

Finally, review how your @ApplicationScoped bean is constructed. Ensure that it has a no-argument constructor or a constructor annotated with @Inject:

@ApplicationScoped
public class MyBean {

  @Inject
  public MyBean(MyDependency dependency) {
    // ...
  }
}

In this example, we’re using constructor injection to inject a MyDependency instance into our MyBean class.

The Final Verdict

By following these steps, you should be able to resolve the issue of CDI failing to find your @ApplicationScoped bean during the quarkus-maven-plugin build process. Remember to carefully review your bean’s annotation, Maven configuration, and Quarkus application setup to ensure that CDI is properly enabled and configured.

Step	Description
1	Verify your bean’s annotation with @ApplicationScoped.
2	Check your Maven configuration for the quarkus-maven-plugin.
3	Update your POM file to include the quarkus-arc and quarkus-weld dependencies.
4	Enable CDI in your Quarkus application by adding quarkus.arc.enabled=true to your application.properties file.
5	Verify your bean’s package and ensure it’s scanned by CDI.
6	Review your bean’s construction and ensure it has a no-argument constructor or a constructor annotated with @Inject.

With these steps, you’ll be well on your way to resolving the mystery of CDI failing to find your @ApplicationScoped bean during the quarkus-maven-plugin build process. Happy coding!

Conclusion

In this article, we’ve embarked on a thrilling adventure to unravel the enigma of CDI failing to find @ApplicationScoped beans during the quarkus-maven-plugin build process. By carefully following the steps outlined above, you should be able to resolve this issue and unlock the full potential of Quarkus CDI. Remember to stay vigilant, and don’t hesitate to reach out for help if you encounter any further issues.

What’s your favorite Quarkus feature? Share your experiences and tips in the comments below!

References

[1] Quarkus CDI Guide: https://quarkus.io/guides/cdi

[2] Quarkus Maven Plugin: https://quarkus

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