Groovy Support in the CLI

The Micronaut Command Line Interface includes special support for Groovy. To create a Groovy application, use the groovy lang option. For example:

Create a Micronaut Groovy application

$ mn create-app hello-world --lang groovy

The above generates a Groovy project, built with Gradle. Use the -build maven flag to generate a project built with Maven instead.

Once you have created an application with the groovy feature, commands like create-controller, create-client etc. generate Groovy files instead of Java. The following example demonstrates this when using interactive mode of the CLI:

Create a bean

$ mn
| Starting interactive mode...
| Enter a command name to run. Use TAB for completion:
mn>
create-bean          create-client        create-controller
create-job           help
mn> create-bean helloBean
| Rendered template Bean.groovy to destination src/main/groovy/hello/world/HelloBean.groovy

The above example demonstrates creating a Groovy bean that looks like the following:

Micronaut Bean

package hello.world
import javax.inject.Singleton
@Singleton
class HelloBean {
}

We can also create a client - don’t forget Micronaut can act as a client or a server!

Create a client

mn> create-client helloClient
| Rendered template Client.groovy to destination src/main/groovy/hello/world/HelloClient.groovy

Micronaut Client

package hello.world
import io.micronaut.http.client.annotation.Client
import io.micronaut.http.annotation.Get
import io.micronaut.http.HttpStatus
@Client("hello")
interface HelloClient {
    @Get
    HttpStatus index()
}

Now let’s create a controller:

Create a controller

mn> create-controller helloController
| Rendered template Controller.groovy to destination src/main/groovy/hello/world/HelloController.groovy
| Rendered template ControllerSpec.groovy to destination src/test/groovy/hello/world/HelloControllerSpec.groovy
mn>

Micronaut Controller

package hello.world
import io.micronaut.http.annotation.Controller
import io.micronaut.http.annotation.Get
import io.micronaut.http.HttpStatus
@Controller("/hello")
class HelloController {
    @Get
    HttpStatus index() {
        return HttpStatus.OK
    }
}

As you can see from the output from the CLI, a Spock test was also generated for you which demonstrates how to test the controller:

HelloControllerSpec.groovy

...
    void "test index"() {
        given:
        HttpResponse response = client.toBlocking().exchange("/hello")
        expect:
        response.status == HttpStatus.OK
    }
...

Notice how you use Micronaut both as client and as a server to test itself.