common handler to display server side validation errors (from rails)

rails-gwt/src/main/java/de/mkristian/gwt/rails/DisplayErrors.java

@@ -0,0 +1,55 @@
+package de.mkristian.gwt.rails;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import org.fusesource.restygwt.client.FailedStatusCodeException;
+import org.fusesource.restygwt.client.Method;
+
+import com.google.gwt.json.client.JSONObject;
+import com.google.gwt.json.client.JSONParser;
+
+
+@Singleton
+public class DisplayErrors {
+
+    public enum Type {
+        PRECONDITIONS, CONFLICT, GENERAL
+    }
+
+    private final Notice notice;
+
+    @Inject
+    public DisplayErrors(Notice notice){
+        this.notice = notice;
+    }
+
+    public Type showMessages(Method method, Throwable exp) {
+        if( exp instanceof FailedStatusCodeException){
+            switch(((FailedStatusCodeException)exp).getStatusCode()){
+                case 422:
+                    JSONObject obj = JSONParser.parseStrict(method.getResponse().getText()).isObject();
+                    if (obj != null){
+                        StringBuffer buf = new StringBuffer();
+                        for(String key : obj.keySet()) {
+                            buf.append(key)
+                                .append(": ")
+                                .append(obj.get(key).toString().replaceAll("\\[\\]", ""))
+                                .append("\n");
+                        }
+                        notice.error(buf.toString());
+                    }
+                    else {
+                        // TODO
+                    }
+                    return Type.PRECONDITIONS;
+                case 409:
+                    // TODO
+                    return Type.CONFLICT;
+                default:
+                    // TODO
+            }
+        }
+        return Type.GENERAL;
+    }
+}