Added JsonSchemaController for generating JSON schema for managed entities.

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/RepositoryRestHandlerAdapter.java

@@ -3,6 +3,7 @@ package org.springframework.data.rest.webmvc;
 import java.util.Arrays;
 
 import org.springframework.core.Ordered;
+import org.springframework.data.rest.webmvc.json.JsonSchemaController;
 import org.springframework.web.method.HandlerMethod;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter;
 
@@ -29,7 +30,8 @@ public class RepositoryRestHandlerAdapter extends ResourceProcessorInvokingHandl
 
   @Override protected boolean supportsInternal(HandlerMethod handlerMethod) {
     return super.supportsInternal(handlerMethod)
-        && RepositoryRestController.class.isAssignableFrom(handlerMethod.getBeanType());
+        && (RepositoryRestController.class.isAssignableFrom(handlerMethod.getBeanType())
+        || JsonSchemaController.class.isAssignableFrom(handlerMethod.getBeanType()));
   }
 
 }

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/RepositoryRestHandlerMapping.java

@@ -10,6 +10,7 @@ import javax.servlet.http.HttpServletRequest;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.core.Ordered;
 import org.springframework.data.rest.repository.RepositoryExporter;
+import org.springframework.data.rest.webmvc.json.JsonSchemaController;
 import org.springframework.orm.jpa.support.OpenEntityManagerInViewInterceptor;
 import org.springframework.web.method.HandlerMethod;
 import org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping;
@@ -57,7 +58,8 @@ public class RepositoryRestHandlerMapping extends RequestMappingHandlerMapping {
   }
 
   @Override protected boolean isHandler(Class<?> beanType) {
-    return RepositoryRestController.class.isAssignableFrom(beanType);
+    return (RepositoryRestController.class.isAssignableFrom(beanType)
+        || JsonSchemaController.class.isAssignableFrom(beanType));
   }
 
   @Override protected void extendInterceptors(List<Object> interceptors) {

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/RepositoryRestMvcConfiguration.java

@@ -9,6 +9,7 @@ import org.springframework.context.annotation.ImportResource;
 import org.springframework.data.rest.repository.UriToDomainObjectUriResolver;
 import org.springframework.data.rest.repository.context.ValidatingRepositoryEventListener;
 import org.springframework.data.rest.repository.jpa.JpaRepositoryExporter;
+import org.springframework.data.rest.webmvc.json.JsonSchemaController;
 import org.springframework.data.rest.webmvc.json.RepositoryAwareJacksonModule;
 import org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor;
 import org.springframework.web.method.support.HandlerMethodArgumentResolver;
@@ -120,6 +121,10 @@ public class RepositoryRestMvcConfiguration {
     return new RepositoryRestController();
   }
 
+  @Bean public JsonSchemaController jsonSchemaController() {
+    return new JsonSchemaController();
+  }
+
   /**
    * Special {@link org.springframework.web.servlet.HandlerAdapter} that only recognizes handler methods defined in the
    * {@link RepositoryRestController} class.

spring-data-rest-webmvc/src/main/java/org/springframework/data/rest/webmvc/json/JsonSchemaController.java

@@ -0,0 +1,65 @@
+package org.springframework.data.rest.webmvc.json;
+
+import java.io.IOException;
+import java.net.URI;
+
+import org.codehaus.jackson.map.ObjectMapper;
+import org.codehaus.jackson.map.SerializationConfig;
+import org.codehaus.jackson.schema.JsonSchema;
+import org.springframework.data.rest.repository.RepositoryExporterSupport;
+import org.springframework.data.rest.repository.RepositoryMetadata;
+import org.springframework.data.rest.webmvc.RepositoryRestController;
+import org.springframework.hateoas.Link;
+import org.springframework.hateoas.Resource;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.server.ServletServerHttpRequest;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RequestMethod;
+import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.util.UriComponentsBuilder;
+
+/**
+ * A controller to output JSON schema based on Jackson's schema generator.
+ *
+ * @author Jon Brisbin
+ */
+public class JsonSchemaController extends RepositoryExporterSupport<JsonSchemaController> {
+
+  private ObjectMapper mapper = new ObjectMapper();
+
+  {
+    mapper.configure(SerializationConfig.Feature.INDENT_OUTPUT, true);
+  }
+
+  @RequestMapping(
+      value = "/{repository}/schema",
+      method = RequestMethod.GET,
+      produces = "application/json"
+  )
+  @ResponseBody
+  public ResponseEntity<?> schemaForRepository(ServletServerHttpRequest request,
+                                               UriComponentsBuilder uriBuilder,
+                                               @PathVariable String repository) throws IOException {
+    URI baseUri = uriBuilder.build().toUri();
+    RepositoryRestController.BASE_URI.set(baseUri);
+
+    RepositoryMetadata repoMeta = repositoryMetadataFor(repository);
+    if(null == repoMeta) {
+      throw new IllegalArgumentException("Resource /" + repository + "/schema not found.");
+    }
+
+    JsonSchema schema = mapper.generateJsonSchema(repoMeta.domainType());
+
+    URI requestUri = UriComponentsBuilder.fromUri(baseUri).path(repository).build().toUri();
+    Resource<JsonSchema> resource = new Resource<JsonSchema>(schema,
+                                                             new Link(request.getURI().toString(), "self"),
+                                                             new Link(requestUri.toString(), repoMeta.rel()));
+
+    String output = mapper.writeValueAsString(resource);
+
+    return new ResponseEntity<String>(output, HttpStatus.OK);
+  }
+
+}