如何在micronaut中用生成的客户端发布

Question

I'm getting an error when posting to a simple hello controller in micronaut. The client seems to be posting as application/json but the controller expects text/plain. How do I fix the client to post as text/plain?

HelloController.java

@Post(value = "/helloBody/{name}", consumes = MediaType.TEXT_PLAIN)
public Single<String> helloBody(@NotBlank String name, @NotBlank @Body String text) {
    return Single.just(name + "sent: " + text);
}

HelloClient.java

@Post(value = "/helloBody/{name}")
Single<String> helloBody(@NotBlank String name, @NotBlank String body);

HelloControllerTest.java

@Test
void testPost() {
    String body = client.helloBody("John", "message").blockingGet();
    assertThat(body).isEqualTo("John sent: message");
}

Error

io.micronaut.http.client.exceptions.HttpClientResponseException: Content Type [application/json] not allowed. Allowed types: [text/plain]
    at io.micronaut.http.client.DefaultHttpClient$10.channelRead0(DefaultHttpClient.java:1799)
    at io.micronaut.http.client.DefaultHttpClient$10.channelRead0(DefaultHttpClient.java:1739)
    at io.netty.channel.SimpleChannelInboundHandler.channelRead(SimpleChannelInboundHandler.java:105)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:374)
    at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:360)
...

Answer 1

You can change this by tell the client to send text/plain as the backend expects.

@Post(value = "/helloBody/{name}", consumes = MediaType.TEXT_PLAIN, produces = MediaType.TEXT_PLAIN)
Single<String> helloBody(@NotBlank String name, @NotBlank String body);

The idea in Micronaut is to make web operations shareable between a controller and a client.

Let's think of a interface called HelloOperations . This is your web interface that can be shared between the client and server.

@Validated
public interface HelloOperations {

  @Post(value = "/helloBody/{name}", consumes = MediaType.TEXT_PLAIN)
  Single<String> helloBody(@NotBlank String name, @NotBlank @Body String text);
}

Now you start implementing the contract in the backend with a controller implementation such as

@Controller
public class HelloController implements HelloOperations {

   @Override
   public Single<String> helloBody(String name, String text)  {

     // do something in here...
   }
}

after that you continue on the client side.

@Client
public interface HelloWorldClient extends HelloOperations {

   @Override
   Single<String> helloBody(String name, String text);
}

Et voilà. You successfully connected them.

Further explanations can be found in the Micronaut documentation at https://docs.micronaut.io/latest/guide/index.html#clientAnnotation