#452 The generator does not work when using @produces to customize the JSON MIME type (#454)

* #452 - The generator does not work when using `@Produces` to customize the JSON MIME type

e.g.
```
@produces(MediaType.APPLICATION_JSON + ";charset=UTF-8")
```

* #452 - The generator does not work when using `@Produces` to customize the JSON MIME type

e.g.
```
@produces(MediaType.APPLICATION_JSON + ";charset=UTF-8")
```

Author: rbygrave

http-generator-core/src/main/java/io/avaje/http/generator/core/JsonBUtil.java

@@ -5,9 +5,14 @@
 import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
-public class JsonBUtil {
+public final class JsonBUtil {
+
   private JsonBUtil() {}
 
+  public static boolean isJsonMimeType(String producesMimeType) {
+    return producesMimeType == null || producesMimeType.toLowerCase().contains("application/json");
+  }
+
   public static Map<String, UType> jsonTypes(ControllerReader reader) {
 
     final Map<String, UType> jsonTypes = new LinkedHashMap<>();

http-generator-javalin/src/main/java/io/avaje/http/generator/javalin/ControllerMethodWriter.java

@@ -4,14 +4,7 @@
 
 import java.util.List;
 
-import io.avaje.http.generator.core.Append;
-import io.avaje.http.generator.core.CoreWebMethod;
-import io.avaje.http.generator.core.MethodParam;
-import io.avaje.http.generator.core.MethodReader;
-import io.avaje.http.generator.core.PathSegments;
-import io.avaje.http.generator.core.UType;
-import io.avaje.http.generator.core.Util;
-import io.avaje.http.generator.core.WebMethod;
+import io.avaje.http.generator.core.*;
 import io.avaje.http.generator.core.openapi.MediaType;
 
 /** Write code to register Web route for a given controller method. */
@@ -158,8 +151,9 @@ private void writeContextReturn() {
   }
 
   private void writeContextReturn(final String resultVariableName) {
-    final var produces = method.produces();
-    if (produces == null || MediaType.APPLICATION_JSON.getValue().equalsIgnoreCase(produces)) {
+    var produces = method.produces();
+    boolean applicationJson = produces == null || MediaType.APPLICATION_JSON.getValue().equalsIgnoreCase(produces);
+    if (applicationJson || JsonBUtil.isJsonMimeType(produces)) {
       if (useJsonB) {
         var uType = UType.parse(method.returnType());
         final boolean isfuture = "java.util.concurrent.CompletableFuture".equals(uType.mainType());
@@ -169,12 +163,19 @@ private void writeContextReturn(final String resultVariableName) {
           }
           writer.append("      try {");
         }
-        writer.append("      %sJsonType.toJson(%s, ctx.contentType(\"application/json\").res().getOutputStream());", uType.shortName(), resultVariableName);
+        if (produces == null) {
+          produces = MediaType.APPLICATION_JSON.getValue();
+        }
+        writer.append("      %sJsonType.toJson(%s, ctx.contentType(\"%s\").res().getOutputStream());", uType.shortName(), resultVariableName, produces);
         if (isfuture || method.isErrorMethod()) {
           writer.append("      } catch (java.io.IOException e) { throw new java.io.UncheckedIOException(e); }");
         }
       } else {
-        writer.append("      ctx.json(%s);", resultVariableName);
+        if (applicationJson) {
+          writer.append("      ctx.json(%s);", resultVariableName);
+        } else {
+          writer.append("      ctx.contentType(\"%s\").json(%s);", produces, resultVariableName);
+        }
       }
     } else if (MediaType.TEXT_HTML.getValue().equalsIgnoreCase(produces)) {
       writer.append("      ctx.html(%s);", resultVariableName);

http-generator-jex/src/main/java/io/avaje/http/generator/jex/ControllerMethodWriter.java

@@ -3,12 +3,7 @@
 import static io.avaje.http.generator.core.ProcessingContext.platform;
 import java.util.List;
 
-import io.avaje.http.generator.core.Append;
-import io.avaje.http.generator.core.MethodParam;
-import io.avaje.http.generator.core.MethodReader;
-import io.avaje.http.generator.core.PathSegments;
-import io.avaje.http.generator.core.Util;
-import io.avaje.http.generator.core.WebMethod;
+import io.avaje.http.generator.core.*;
 import io.avaje.http.generator.core.openapi.MediaType;
 
 /**
@@ -102,6 +97,8 @@ private void writeContextReturn() {
       writer.append("ctx.html(");
     } else if (produces.equalsIgnoreCase(MediaType.TEXT_PLAIN.getValue())) {
       writer.append("ctx.text(");
+    } else if (JsonBUtil.isJsonMimeType(produces)) {
+      writer.append("ctx.contentType(\"%s\").json(", produces);
     } else {
       writer.append("ctx.contentType(\"%s\").write(", produces);
     }

tests/test-javalin-jsonb/src/main/java/org/example/myapp/web/HelloController.java

@@ -82,6 +82,7 @@ List<HelloDto> findByName(String name, @QueryParam("my-param") @Default("one") S
   /**
    * Simple example post with JSON body response.
    */
+  @Produces(MediaType.APPLICATION_JSON_PATCH_JSON)
   @Post
   HelloDto post(HelloDto dto) {
     dto.name = "posted";

tests/test-javalin-jsonb/src/main/resources/public/openapi.json

@@ -1,7 +1,7 @@
 {
 	"openapi" : "3.0.1",
 	"info" : {
-		"title" : "Example service showing off the Path extension method of controller",
+		"title" : "Example service",
 		"description" : "Example Javalin controllers with Java and Maven",
 		"version" : ""
 	},
@@ -14,11 +14,11 @@
 	"tags" : [
 		{
 			"name" : "tag1",
-			"description" : "this is added to openapi tags"
+			"description" : "it's somethin"
 		},
 		{
 			"name" : "tag1",
-			"description" : "it's somethin"
+			"description" : "this is added to openapi tags"
 		}
 	],
 	"paths" : {
@@ -320,7 +320,7 @@
 					"201" : {
 						"description" : "",
 						"content" : {
-							"application/json" : {
+							"application/json-patch+json" : {
 								"schema" : {
 									"$ref" : "#/components/schemas/HelloDto"
 								}

tests/test-javalin/src/main/java/org/example/myapp/web/HelloController.java

@@ -82,6 +82,7 @@ List<HelloDto> findByName(String name, @QueryParam("my-param") @Default("one") S
   /**
    * Simple example post with JSON body response.
    */
+  @Produces(MediaType.APPLICATION_JSON + ";charset=UTF-8")
   @Post
   HelloDto post(HelloDto dto) {
     dto.name = "posted";

tests/test-javalin/src/main/resources/public/openapi.json

@@ -310,7 +310,7 @@
 					"201" : {
 						"description" : "",
 						"content" : {
-							"application/json" : {
+							"application/json;charset=UTF-8" : {
 								"schema" : {
 									"$ref" : "#/components/schemas/HelloDto"
 								}