Where a given String conversion is supported, register Feign Param.Expanders

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/FeignClientsConfiguration.java

 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2013-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,6 +33,9 @@ import org.springframework.cloud.netflix.feign.support.SpringMvcContract;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Scope;
+import org.springframework.core.convert.ConversionService;
+import org.springframework.format.support.DefaultFormattingConversionService;
+import org.springframework.format.support.FormattingConversionService;
 
 import com.netflix.hystrix.HystrixCommand;
 
@@ -56,6 +59,9 @@ public class FeignClientsConfiguration {
 	@Autowired(required = false)
 	private List<AnnotatedParameterProcessor> parameterProcessors = new ArrayList<>();
 
+	@Autowired(required = false)
+	private List<FeignFormatterRegistrar> feignFormatterRegistrars = new ArrayList<>();
+
 	@Bean
 	@ConditionalOnMissingBean
 	public Decoder feignDecoder() {
@@ -70,8 +76,17 @@ public class FeignClientsConfiguration {
 
 	@Bean
 	@ConditionalOnMissingBean
-	public Contract feignContract() {
-		return new SpringMvcContract(this.parameterProcessors);
+	public Contract feignContract(ConversionService feignConversionService) {
+		return new SpringMvcContract(this.parameterProcessors, feignConversionService);
+	}
+
+	@Bean
+	public FormattingConversionService feignConversionService() {
+		FormattingConversionService conversionService = new DefaultFormattingConversionService();
+		for (FeignFormatterRegistrar feignFormatterRegistrar : feignFormatterRegistrars) {
+			feignFormatterRegistrar.registerFormatters(conversionService);
+		}
+		return conversionService;
 	}
 
 	@Configuration

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/FeignFormatterRegistrar.java

+/*
+ * Copyright 2013-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.cloud.netflix.feign;
+
+import org.springframework.format.FormatterRegistrar;
+import org.springframework.format.support.FormattingConversionService;
+
+/**
+ * Allows an application to customize the Feign {@link FormattingConversionService}.
+ *
+ * @author Matt Benson
+ */
+public interface FeignFormatterRegistrar extends FormatterRegistrar {
+
+}

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/feign/support/SpringMvcContract.java

 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2013-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -23,6 +23,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
@@ -33,16 +34,19 @@ import org.springframework.cloud.netflix.feign.annotation.RequestParamParameterP
 import org.springframework.core.DefaultParameterNameDiscoverer;
 import org.springframework.core.ParameterNameDiscoverer;
 import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.core.convert.ConversionService;
+import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.util.Assert;
 import org.springframework.web.bind.annotation.RequestMapping;
 
-import static feign.Util.checkState;
-import static feign.Util.emptyToNull;
-import static org.springframework.core.annotation.AnnotatedElementUtils.findMergedAnnotation;
-
 import feign.Contract;
 import feign.Feign;
 import feign.MethodMetadata;
+import feign.Param;
+
+import static feign.Util.checkState;
+import static feign.Util.emptyToNull;
+import static org.springframework.core.annotation.AnnotatedElementUtils.findMergedAnnotation;
 
 /**
  * @author Spencer Gibb
@@ -58,14 +62,25 @@ public class SpringMvcContract extends Contract.BaseContract {
 	private final Map<Class<? extends Annotation>, AnnotatedParameterProcessor> annotatedArgumentProcessors;
 	private final Map<String, Method> processedMethods = new HashMap<>();
 
+	private final ConversionService conversionService;
+	private final Param.Expander expander;
+
 	public SpringMvcContract() {
 		this(Collections.<AnnotatedParameterProcessor> emptyList());
 	}
 
 	public SpringMvcContract(
 			List<AnnotatedParameterProcessor> annotatedParameterProcessors) {
+		this(annotatedParameterProcessors, new DefaultConversionService());
+	}
+
+	public SpringMvcContract(
+			List<AnnotatedParameterProcessor> annotatedParameterProcessors,
+			ConversionService conversionService) {
 		Assert.notNull(annotatedParameterProcessors,
 				"Parameter processors can not be null.");
+		Assert.notNull(conversionService,
+				"ConversionService can not be null.");
 
 		List<AnnotatedParameterProcessor> processors;
 		if (!annotatedParameterProcessors.isEmpty()) {
@@ -75,6 +90,8 @@ public class SpringMvcContract extends Contract.BaseContract {
 			processors = getDefaultAnnotatedArgumentsProcessors();
 		}
 		this.annotatedArgumentProcessors = toAnnotatedArgumentProcessorMap(processors);
+		this.conversionService = conversionService;
+		this.expander = new ConvertingExpander(conversionService);
 	}
 
 	@Override
@@ -148,6 +165,8 @@ public class SpringMvcContract extends Contract.BaseContract {
 
 		// headers
 		parseHeaders(data, method, methodMapping);
+
+		data.indexToExpander(new LinkedHashMap<Integer, Param.Expander>());
 	}
 
 	private void checkAtMostOne(Method method, Object[] values, String fieldName) {
@@ -184,6 +203,11 @@ public class SpringMvcContract extends Contract.BaseContract {
 						processParameterAnnotation);
 			}
 		}
+		if (isHttpAnnotation && data.indexToExpander().get(paramIndex) == null
+				&& this.conversionService.canConvert(
+						method.getParameterTypes()[paramIndex], String.class)) {
+			data.indexToExpander().put(paramIndex, expander);
+		}
 		return isHttpAnnotation;
 	}
 
@@ -293,4 +317,18 @@ public class SpringMvcContract extends Contract.BaseContract {
 		}
 	}
 
+	public static class ConvertingExpander implements Param.Expander {
+
+		private final ConversionService conversionService;
+
+		public ConvertingExpander(ConversionService conversionService) {
+			this.conversionService = conversionService;
+		}
+
+		@Override
+		public String expand(Object value) {
+			return conversionService.convert(value, String.class);
+		}
+
+	}
 }

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/support/SpringMvcContractTests.java

+/*
+ * Copyright 2013-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.springframework.cloud.netflix.feign.support;
 
 import java.lang.reflect.InvocationTargetException;

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/feign/valid/FeignClientTests.java

 /*
- * Copyright 2013-2015 the original author or authors.
+ * Copyright 2013-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -18,9 +18,11 @@ package org.springframework.cloud.netflix.feign.valid;
 
 import java.lang.reflect.InvocationHandler;
 import java.lang.reflect.Proxy;
+import java.text.ParseException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Locale;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 
@@ -34,6 +36,7 @@ import org.springframework.boot.test.SpringApplicationConfiguration;
 import org.springframework.boot.test.WebIntegrationTest;
 import org.springframework.cloud.netflix.feign.EnableFeignClients;
 import org.springframework.cloud.netflix.feign.FeignClient;
+import org.springframework.cloud.netflix.feign.FeignFormatterRegistrar;
 import org.springframework.cloud.netflix.feign.ribbon.LoadBalancerFeignClient;
 import org.springframework.cloud.netflix.feign.support.FallbackCommand;
 import org.springframework.cloud.netflix.ribbon.RibbonClient;
@@ -41,6 +44,8 @@ import org.springframework.cloud.netflix.ribbon.RibbonClients;
 import org.springframework.cloud.netflix.ribbon.StaticServerList;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.format.Formatter;
+import org.springframework.format.FormatterRegistry;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
@@ -110,6 +115,23 @@ public class FeignClientTests {
 	@Autowired
 	HystrixClient hystrixClient;
 
+	protected enum Arg {
+		A, B;
+
+		@Override
+		public String toString() {
+			return name().toLowerCase(Locale.ENGLISH);
+		}
+	}
+
+	protected static class OtherArg {
+		public final String value;
+
+		public OtherArg(String value) {
+			this.value = value;
+		}
+	}
+
 	@FeignClient(value = "localapp", configuration = TestClientConfig.class)
 	protected interface TestClient {
 		@RequestMapping(method = RequestMethod.GET, value = "/hello")
@@ -147,6 +169,12 @@ public class FeignClientTests {
 				produces = "application/vnd.io.spring.cloud.test.v1+json",
 				value = "/complex")
 		String moreComplexContentType(String body);
+
+		@RequestMapping(method = RequestMethod.GET, value = "/tostring")
+		String getToString(@RequestParam("arg") Arg arg);
+
+		@RequestMapping(method = RequestMethod.GET, value = "/tostring2")
+		String getToString(@RequestParam("arg") OtherArg arg);
 	}
 
 	public static class TestClientConfig {
@@ -242,6 +270,28 @@ public class FeignClientTests {
 	})
 	protected static class Application {
 
+		@Bean
+		FeignFormatterRegistrar feignFormatterRegistrar() {
+			return new FeignFormatterRegistrar() {
+
+				@Override
+				public void registerFormatters(FormatterRegistry registry) {
+					registry.addFormatter(new Formatter<OtherArg>() {
+
+						@Override
+						public String print(OtherArg object, Locale locale) {
+							return object.value;
+						}
+
+						@Override
+						public OtherArg parse(String text, Locale locale)
+								throws ParseException {
+							return new OtherArg(text);
+						}
+					});
+				}
+			};
+		}
 
 		@RequestMapping(method = RequestMethod.GET, value = "/hello")
 		public Hello getHello() {
@@ -304,6 +354,16 @@ public class FeignClientTests {
 			return "{\"value\":\"OK\"}";
 		}
 
+		@RequestMapping(method = RequestMethod.GET, value = "/tostring")
+		String getToString(@RequestParam("arg") Arg arg) {
+			return arg.toString();
+		}
+
+		@RequestMapping(method = RequestMethod.GET, value = "/tostring2")
+		String getToString(@RequestParam("arg") OtherArg arg) {
+			return arg.value;
+		}
+
 		public static void main(String[] args) {
 			new SpringApplicationBuilder(Application.class).properties(
 					"spring.application.name=feignclienttest",
@@ -433,6 +493,14 @@ public class FeignClientTests {
 	}
 
 	@Test
+	public void testConvertingExpander() {
+		assertEquals(Arg.A.toString(), testClient.getToString(Arg.A));
+		assertEquals(Arg.B.toString(), testClient.getToString(Arg.B));
+
+		assertEquals("foo", testClient.getToString(new OtherArg("foo")));
+	}
+
+	@Test
 	public void testHystrixFallbackWorks() {
 		Hello hello = hystrixClient.fail();
 		assertNotNull("hello was null", hello);