Add annotation support for HX-Retarget

README.md

@@ -114,6 +114,7 @@ The following annotations are currently supported:
 * [@HxRefresh](https://javadoc.io/doc/io.github.wimdeblauwe/htmx-spring-boot/latest/io/github/wimdeblauwe/htmx/spring/boot/mvc/HxRefresh.html)
 * [@HxReplaceUrl](https://javadoc.io/doc/io.github.wimdeblauwe/htmx-spring-boot/latest/io/github/wimdeblauwe/htmx/spring/boot/mvc/HxReplaceUrl.html)
 * [@HxReswap](https://javadoc.io/doc/io.github.wimdeblauwe/htmx-spring-boot/latest/io/github/wimdeblauwe/htmx/spring/boot/mvc/HxReswap.html)
+* [@HxRetarget](https://javadoc.io/doc/io.github.wimdeblauwe/htmx-spring-boot/latest/io/github/wimdeblauwe/htmx/spring/boot/mvc/HxRetarget.html)
 * [@HxTrigger](https://javadoc.io/doc/io.github.wimdeblauwe/htmx-spring-boot/latest/io/github/wimdeblauwe/htmx/spring/boot/mvc/HxTrigger.html)
 
 >**Note** Please refer to the related Javadoc to learn more about the available options.

htmx-spring-boot/src/main/java/io/github/wimdeblauwe/htmx/spring/boot/mvc/HtmxHandlerInterceptor.java

@@ -35,6 +35,7 @@ public boolean preHandle(HttpServletRequest request,
             setHxRedirect(response, method);
             setHxReplaceUrl(response, method);
             setHxReswap(response, method);
+            setHxRetarget(response, method);
             setHxTrigger(response, method);
             setHxRefresh(response, method);
             setVary(request, response);
@@ -89,6 +90,13 @@ private void setHxReswap(HttpServletResponse response, Method method) {
         }
     }
 
+    private void setHxRetarget(HttpServletResponse response, Method method) {
+        HxRetarget methodAnnotation = AnnotatedElementUtils.findMergedAnnotation(method, HxRetarget.class);
+        if (methodAnnotation != null) {
+            response.setHeader(HX_RETARGET.getValue(), methodAnnotation.value());
+        }
+    }
+
     private void setHxTrigger(HttpServletResponse response, Method method) {
         HxTrigger methodAnnotation = AnnotatedElementUtils.findMergedAnnotation(method, HxTrigger.class);
         if (methodAnnotation != null) {

htmx-spring-boot/src/main/java/io/github/wimdeblauwe/htmx/spring/boot/mvc/HxRetarget.java

@@ -0,0 +1,23 @@
+package io.github.wimdeblauwe.htmx.spring.boot.mvc;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation to specify a CSS selector that updates the target of
+ * the content update to a different element on the page.
+ *
+ * @see <a href="https://htmx.org/reference/#response_headers">HX-Retarget</a>
+ */
+@Target({ElementType.TYPE, ElementType.METHOD})
+@Retention(RetentionPolicy.RUNTIME)
+public @interface HxRetarget {
+
+    /**
+     * A CSS selector that updates the target of the content update to a different element on the page.
+     */
+    String value();
+
+}

htmx-spring-boot/src/test/java/io/github/wimdeblauwe/htmx/spring/boot/mvc/HtmxHandlerInterceptorTest.java

@@ -124,4 +124,11 @@ public void testHxReswap() throws Exception {
                .andExpect(header().string("HX-Reswap", "innerHTML swap:300ms"));
     }
 
+    @Test
+    public void testHxRetarget() throws Exception {
+        mockMvc.perform(get("/hx-retarget"))
+               .andExpect(status().isOk())
+               .andExpect(header().string("HX-Retarget", "#target"));
+    }
+
 }

htmx-spring-boot/src/test/java/io/github/wimdeblauwe/htmx/spring/boot/mvc/TestController.java

@@ -105,4 +105,11 @@ public String hxReswap() {
         return "";
     }
 
+    @GetMapping("/hx-retarget")
+    @HxRetarget("#target")
+    @ResponseBody
+    public String hxRetarget() {
+        return "";
+    }
+
 }