Refactor/improve example schema generator (#552)

* feat: log allowed payloadTypes to console

* fix: handling of string schema

Co-authored-by: sam0r040 <93372330+sam0r040@users.noreply.github.com>

---------

Co-authored-by: sam0r040 <93372330+sam0r040@users.noreply.github.com>

Author: timonback

springwolf-core/src/main/java/io/github/stavshamir/springwolf/asyncapi/controller/PublishingPayloadCreator.java

@@ -8,8 +8,10 @@
 import io.swagger.v3.oas.models.media.Schema;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
+import org.apache.commons.lang3.StringUtils;
 
 import java.text.MessageFormat;
+import java.util.List;
 
 /**
  * Used in plugins with publishing enabled.
@@ -23,12 +25,14 @@ public class PublishingPayloadCreator {
     private final ObjectMapper objectMapper;
 
     public Result createPayloadObject(MessageDto message) {
-
         String messagePayloadType = message.getPayloadType();
-        for (Schema<?> value : schemasService.getDefinitions().values()) {
-            String schemaPayloadType = value.getName();
+
+        List<String> knownSchemaNames = schemasService.getDefinitions().values().stream()
+                .map(Schema::getName)
+                .toList();
+        for (String schemaPayloadType : knownSchemaNames) {
             // security: match against user input, but always use our controlled data from the DefaultSchemaService
-            if (schemaPayloadType.equals(messagePayloadType)) {
+            if (schemaPayloadType != null && schemaPayloadType.equals(messagePayloadType)) {
                 try {
                     Class<?> payloadClass = Class.forName(schemaPayloadType);
                     Object payload = objectMapper.readValue(message.getPayload(), payloadClass);
@@ -44,7 +48,9 @@ public Result createPayloadObject(MessageDto message) {
 
         String errorMessage = MessageFormat.format(
                 "Specified payloadType {0} is not a registered springwolf schema.", messagePayloadType);
-        log.info(errorMessage);
+        String knownPayloadsMessage =
+                MessageFormat.format(" Known payloadTypes: [{0}]", StringUtils.join(knownSchemaNames, ", "));
+        log.info(errorMessage + knownPayloadsMessage);
         return new Result(null, errorMessage);
     }
 

springwolf-core/src/main/java/io/github/stavshamir/springwolf/schemas/DefaultSchemasService.java

@@ -122,6 +122,7 @@ private void processAsyncApiPayloadAnnotation(Map<String, Schema> schemas, Strin
     private String registerString() {
         String schemaName = "String";
         StringSchema schema = new StringSchema();
+        schema.setName(String.class.getName());
 
         this.definitions.put(schemaName, schema);
         postProcessSchema(schema);

springwolf-core/src/main/java/io/github/stavshamir/springwolf/schemas/example/ExampleJsonGenerator.java

@@ -56,9 +56,8 @@ private static String DEFAULT_UNKNOWN_SCHEMA_STRING_EXAMPLE(String format) {
     @Override
     public Object fromSchema(Schema schema, Map<String, Schema> definitions) {
         try {
-            String exampleString = buildSchema(schema, definitions);
-            return objectMapper.readValue(exampleString, Object.class);
-        } catch (JsonProcessingException | ExampleGeneratingException ex) {
+            return buildSchemaInternal(schema, definitions, new HashSet<>());
+        } catch (ExampleGeneratingException ex) {
             log.info("Failed to build json example for schema {}", schema.getName(), ex);
         }
         return null;
@@ -104,6 +103,11 @@ private static JsonNode getExampleValueFromSchemaAnnotation(Schema schema) {
             return null;
         }
 
+        // Return directly, when we have processed this before
+        if (exampleValue instanceof JsonNode) {
+            return (JsonNode) exampleValue;
+        }
+
         // Create an ObjectNode to hold the example JSON
         JsonNode exampleNode = objectMapper.createObjectNode();
 

springwolf-core/src/test/java/io/github/stavshamir/springwolf/schemas/example/ExampleJsonGeneratorTest.java

@@ -36,7 +36,7 @@ void build() {
 
             Object actual = generator.fromSchema(schema, emptyMap());
 
-            assertThat(actual).isEqualTo("string");
+            assertThat(actual.toString()).isEqualTo("\"string\"");
         }
 
         @Test

springwolf-core/src/test/resources/schemas/api-payload.json

@@ -3,6 +3,6 @@
     "maxLength" : 10,
     "type" : "string",
     "description" : "The payload in the envelop",
-    "example" : "string"
+    "example" : "\"string\""
   }
 }

springwolf-examples/springwolf-kafka-example/src/test/resources/asyncapi.json

@@ -564,9 +564,10 @@
       },
       "String": {
         "type": "string",
-        "example": "string",
+        "example": "\"string\"",
         "x-json-schema": {
           "$schema": "https://json-schema.org/draft-04/schema#",
+          "name": "java.lang.String",
           "type": "string"
         }
       },
@@ -606,7 +607,7 @@
         "maxLength": 100,
         "type": "string",
         "description": "Payload description using @Schema annotation and @AsyncApiPayload within envelope class",
-        "example": "string",
+        "example": "\"string\"",
         "x-json-schema": {
           "$schema": "https://json-schema.org/draft-04/schema#",
           "description": "Payload description using @Schema annotation and @AsyncApiPayload within envelope class",