err handler on specific exception/code fix #382

Author: jknack

coverage-report/src/test/java/org/jooby/issues/Issue382.java

@@ -0,0 +1,63 @@
+package org.jooby.issues;
+
+import org.jooby.Err;
+import org.jooby.test.ServerFeature;
+import org.junit.Test;
+
+public class Issue382 extends ServerFeature {
+
+  {
+
+    get("/err1", () -> {
+      throw new IllegalArgumentException("err1");
+    });
+
+    get("/err2", () -> {
+      throw new IllegalStateException("err2");
+    });
+
+    get("/400", () -> {
+      throw new Err(404);
+    });
+
+    get("/500", () -> {
+      throw new Err(500);
+    });
+
+    err(IllegalArgumentException.class, (req, rsp, err) -> {
+      rsp.send(err.getCause().getClass().getSimpleName());
+    });
+
+    err(IllegalStateException.class, (req, rsp, err) -> {
+      rsp.send(err.getCause().getClass().getSimpleName());
+    });
+
+    err(404, (req, rsp, err) -> {
+      rsp.send("Not found");
+    });
+
+    err((req, rsp, err) -> {
+      rsp.send("Fallback");
+    });
+  }
+
+  @Test
+  public void shouldHandleSpecificErrTypes() throws Exception {
+    request()
+        .get("/err1")
+        .expect("IllegalArgumentException");
+
+    request()
+        .get("/err2")
+        .expect("IllegalStateException");
+
+    request()
+        .get("/400")
+        .expect("Not found");
+
+    request()
+        .get("/500")
+        .expect("Fallback");
+  }
+
+}

jooby/src/main/java/org/jooby/Routes.java

@@ -2492,5 +2492,40 @@ Route.Collection complete(String method, String pattern, Route.Complete handler,
    * @param err A route error handler.
    * @return This jooby instance.
    */
-  Routes err(final Err.Handler err);
+  Routes err(Err.Handler err);
+
+  /**
+   * Setup a route error handler.The error handler will be executed if the current exception is an
+   * instance of this type.
+   *
+   * @param type Exception type. The error handler will be executed if the current exception is an
+   *        instance of this type.
+   * @param handler A route error handler.
+   * @return This jooby instance.
+   */
+  default Routes err(final Class<? extends Throwable> type, final Err.Handler handler) {
+    return err((req, rsp, err) -> {
+      Throwable cause = err.getCause();
+      if (type.isInstance(cause)) {
+        handler.handle(req, rsp, err);
+      }
+    });
+  }
+
+  /**
+   * Setup a route error handler. The error handler will be executed if current status code matches
+   * the one provided.
+   *
+   * @param statusCode The status code to match.
+   * @param handler A route error handler.
+   * @return This jooby instance.
+   */
+  default Routes err(final int statusCode, final Err.Handler handler) {
+    return err((req, rsp, err) -> {
+      if (statusCode == err.statusCode()) {
+        handler.handle(req, rsp, err);
+      }
+    });
+  }
+
 }

md/err.md

@@ -63,7 +63,7 @@ HTTP status code will be set too.
 
 ## custom err handler
 
-If the default view resolution and/or err model isn't enough, you can create your own err handler.
+If the default view resolution and/or err model isn't enough, you can create your own err handler:
 
 ```java
 {
@@ -75,9 +75,48 @@ If the default view resolution and/or err model isn't enough, you can create you
 }
 ```
 
-Err handler are executed in the order they were provided (like routes, parser and renderers).
+Err handler are executed in the order they were provided (like routes, parsers and renderers).
 The first err handler that send an output wins!
 
+### catch specific exception or status code
+
+
+```java
+{
+  err(MyException1.class, (req, rsp, err) -> {
+    MyException1 cause = (MyException1) err.getCause();
+    // handle MyException1
+  });
+
+  err(MyException2.class, (req, rsp, err) -> {
+    MyException2 cause = (MyException2) err.getCause();
+    // handle MyException2
+  });
+
+  err((req, rsp, err) -> {
+    // handle any other exception
+  });
+}
+```
+
+Or you can catch exception base on their response status code (see next section):
+
+```java
+{
+  err(404, (req, rsp, err) -> {
+    // handle 404
+  });
+
+  err(503, (req, rsp, err) -> {
+    // handle 503
+  });
+
+  err((req, rsp, err) -> {
+    // handle any other exception
+  });
+}
+```
+
 ## status code
 
 Default status code is ```500```, except for:
@@ -106,6 +145,4 @@ or add a new entry in the ```application.conf``` file:
 err.com.security.Forbidden = 403
 ```
 
-```java
-throw new Forbidden();
-```
+So, now if you throw a ```com.security.Forbidden``` exception the status code will be ```403```.