Fix writing issues (#7749)

* A root component with @DesignRoot must always use its superclass for
default values. Otherwise the written design will be empty as the
design is read in the constructor.

* A component which is not the root must not write its component tree
if the component tree is generated in the constructor. This is a
simplification which should be good enough for most cases (can't add
children in constructor and also using addComponent - in this case
the component added with addComponent will not be written).

* Test cases for nested templates

Change-Id: I3a384d1d8654b9865a3a790ebeb055a300a62135

11 files changed, 73 insertions, 25 deletions

diff --git a/server/src/com/vaadin/ui/AbstractComponent.java b/server/src/com/vaadin/ui/AbstractComponent.java
index 0b9f8bd244..83833b75ce 100644
--- a/server/src/com/vaadin/ui/AbstractComponent.java
+++ b/server/src/com/vaadin/ui/AbstractComponent.java
@@ -1206,8 +1206,7 @@ public abstract class AbstractComponent extends AbstractClientConnector
     public void writeDesign(Element design, DesignContext designContext) {
         // clear element contents
         DesignAttributeHandler.clearElement(design);
-        AbstractComponent def = designContext.getDefaultInstance(this
-                .getClass());
+        AbstractComponent def = designContext.getDefaultInstance(this);
         Attributes attr = design.attributes();
         // handle default attributes
         for (String attribute : getDefaultAttributes()) {
diff --git a/server/src/com/vaadin/ui/AbstractField.java b/server/src/com/vaadin/ui/AbstractField.java
index c3e2036936..e40bdbde68 100644
--- a/server/src/com/vaadin/ui/AbstractField.java
+++ b/server/src/com/vaadin/ui/AbstractField.java
@@ -1803,7 +1803,7 @@ public abstract class AbstractField<T> extends AbstractComponent implements
     @Override
     public void writeDesign(Element design, DesignContext designContext) {
         super.writeDesign(design, designContext);
-        AbstractField def = designContext.getDefaultInstance(this.getClass());
+        AbstractField def = designContext.getDefaultInstance(this);
         Attributes attr = design.attributes();
         // handle readonly
         DesignAttributeHandler.writeAttribute("readonly", attr,
diff --git a/server/src/com/vaadin/ui/AbstractOrderedLayout.java b/server/src/com/vaadin/ui/AbstractOrderedLayout.java
index cd5609f091..b105d53fce 100644
--- a/server/src/com/vaadin/ui/AbstractOrderedLayout.java
+++ b/server/src/com/vaadin/ui/AbstractOrderedLayout.java
@@ -533,13 +533,17 @@ public abstract class AbstractOrderedLayout extends AbstractLayout implements
         // synchronize default attributes
         super.writeDesign(design, designContext);
         // handle margin
-        AbstractOrderedLayout def = designContext.getDefaultInstance(this
-                .getClass());
+        AbstractOrderedLayout def = (AbstractOrderedLayout) designContext
+                .getDefaultInstance(this);
         if (getMargin().getBitMask() != def.getMargin().getBitMask()) {
             design.attr("margin", "");
         }
         // handle children
         Element designElement = design;
+        if (!designContext.shouldWriteChildren(this, def)) {
+            return;
+        }
+
         for (Component child : this) {
             Element childNode = designContext.createNode(child);
             designElement.appendChild(childNode);
diff --git a/server/src/com/vaadin/ui/AbstractSplitPanel.java b/server/src/com/vaadin/ui/AbstractSplitPanel.java
index 9c33665c1c..4c85311075 100644
--- a/server/src/com/vaadin/ui/AbstractSplitPanel.java
+++ b/server/src/com/vaadin/ui/AbstractSplitPanel.java
@@ -627,8 +627,8 @@ public abstract class AbstractSplitPanel extends AbstractComponentContainer {
         super.writeDesign(design, designContext);
         // handle custom attributes (write only if a value is not the
         // default value)
-        AbstractSplitPanel def = designContext.getDefaultInstance(this
-                .getClass());
+        AbstractSplitPanel def = (AbstractSplitPanel) designContext
+                .getDefaultInstance(this);
         if (getSplitPosition() != def.getSplitPosition()
                 || !def.getSplitPositionUnit().equals(getSplitPositionUnit())) {
             String splitPositionString = asString(getSplitPosition())
diff --git a/server/src/com/vaadin/ui/AbstractTextField.java b/server/src/com/vaadin/ui/AbstractTextField.java
index 8bca74936a..adeb1cb69f 100644
--- a/server/src/com/vaadin/ui/AbstractTextField.java
+++ b/server/src/com/vaadin/ui/AbstractTextField.java
@@ -803,8 +803,8 @@ public abstract class AbstractTextField extends AbstractField<String> implements
     @Override
     public void writeDesign(Element design, DesignContext designContext) {
         super.writeDesign(design, designContext);
-        AbstractTextField def = designContext.getDefaultInstance(this
-                .getClass());
+        AbstractTextField def = (AbstractTextField) designContext
+                .getDefaultInstance(this);
         Attributes attr = design.attributes();
         DesignAttributeHandler.writeAttribute("maxlength", attr,
                 getMaxLength(), def.getMaxLength(), Integer.class);
diff --git a/server/src/com/vaadin/ui/Button.java b/server/src/com/vaadin/ui/Button.java
index 9b50b5eebc..7063568f26 100644
--- a/server/src/com/vaadin/ui/Button.java
+++ b/server/src/com/vaadin/ui/Button.java
@@ -727,7 +727,7 @@ public class Button extends AbstractComponent implements
     public void writeDesign(Element design, DesignContext designContext) {
         super.writeDesign(design, designContext);
         Attributes attr = design.attributes();
-        Button def = designContext.getDefaultInstance(this.getClass());
+        Button def = (Button) designContext.getDefaultInstance(this);
         String content = getCaption();
         if (content != null) {
             design.html(content);
diff --git a/server/src/com/vaadin/ui/Panel.java b/server/src/com/vaadin/ui/Panel.java
index b0242cc32d..0c2a3f580b 100644
--- a/server/src/com/vaadin/ui/Panel.java
+++ b/server/src/com/vaadin/ui/Panel.java
@@ -365,7 +365,7 @@ public class Panel extends AbstractSingleComponentContainer implements
     public void writeDesign(Element design, DesignContext designContext) {
         super.writeDesign(design, designContext);
         // handle tabindex
-        Panel def = designContext.getDefaultInstance(this.getClass());
+        Panel def = (Panel) designContext.getDefaultInstance(this);
         DesignAttributeHandler.writeAttribute("tabindex", design.attributes(),
                 getTabIndex(), def.getTabIndex(), Integer.class);
     }
diff --git a/server/src/com/vaadin/ui/PasswordField.java b/server/src/com/vaadin/ui/PasswordField.java
index 974a1c2c10..1894804775 100644
--- a/server/src/com/vaadin/ui/PasswordField.java
+++ b/server/src/com/vaadin/ui/PasswordField.java
@@ -107,8 +107,8 @@ public class PasswordField extends AbstractTextField {
     @Override
     public void writeDesign(Element design, DesignContext designContext) {
         super.writeDesign(design, designContext);
-        AbstractTextField def = designContext.getDefaultInstance(this
-                .getClass());
+        AbstractTextField def = (AbstractTextField) designContext
+                .getDefaultInstance(this);
         Attributes attr = design.attributes();
         DesignAttributeHandler.writeAttribute("value", attr, getValue(),
                 def.getValue(), String.class);
diff --git a/server/src/com/vaadin/ui/TabSheet.java b/server/src/com/vaadin/ui/TabSheet.java
index 330acacfd0..a264692acb 100644
--- a/server/src/com/vaadin/ui/TabSheet.java
+++ b/server/src/com/vaadin/ui/TabSheet.java
@@ -1623,7 +1623,7 @@ public class TabSheet extends AbstractComponentContainer implements Focusable,
     @Override
     public void writeDesign(Element design, DesignContext designContext) {
         super.writeDesign(design, designContext);
-        TabSheet def = designContext.getDefaultInstance(this.getClass());
+        TabSheet def = (TabSheet) designContext.getDefaultInstance(this);
         Attributes attr = design.attributes();
         // handle tab index
         DesignAttributeHandler.writeAttribute("tabindex", attr, getTabIndex(),
diff --git a/server/src/com/vaadin/ui/TextField.java b/server/src/com/vaadin/ui/TextField.java
index cd919ded9c..563810c76a 100644
--- a/server/src/com/vaadin/ui/TextField.java
+++ b/server/src/com/vaadin/ui/TextField.java
@@ -129,8 +129,8 @@ public class TextField extends AbstractTextField {
     @Override
     public void writeDesign(Element design, DesignContext designContext) {
         super.writeDesign(design, designContext);
-        AbstractTextField def = designContext.getDefaultInstance(this
-                .getClass());
+        AbstractTextField def = (AbstractTextField) designContext
+                .getDefaultInstance(this);
         Attributes attr = design.attributes();
         DesignAttributeHandler.writeAttribute("value", attr, getValue(),
                 def.getValue(), String.class);
diff --git a/server/src/com/vaadin/ui/declarative/DesignContext.java b/server/src/com/vaadin/ui/declarative/DesignContext.java
index b196c84b02..214040b54d 100644
--- a/server/src/com/vaadin/ui/declarative/DesignContext.java
+++ b/server/src/com/vaadin/ui/declarative/DesignContext.java
@@ -28,7 +28,10 @@ import org.jsoup.nodes.Document;
 import org.jsoup.nodes.Element;
 import org.jsoup.nodes.Node;
 
+import com.vaadin.annotations.DesignRoot;
+import com.vaadin.ui.AbstractComponent;
 import com.vaadin.ui.Component;
+import com.vaadin.ui.HasComponents;
 
 /**
  * This class contains contextual information that is collected when a component
@@ -42,8 +45,8 @@ import com.vaadin.ui.Component;
 public class DesignContext implements Serializable {
 
     // cache for object instances
-    private static Map<Class<?>, Object> instanceCache = Collections
-            .synchronizedMap(new HashMap<Class<?>, Object>());
+    private static Map<Class<?>, Component> instanceCache = Collections
+            .synchronizedMap(new HashMap<Class<?>, Component>());
 
     // The root component of the component hierarchy
     private Component rootComponent = null;
@@ -254,22 +257,38 @@ public class DesignContext implements Serializable {
      * Returns the default instance for the given class. The instance must not
      * be modified by the caller.
      * 
-     * @param instanceClass
+     * @param abstractComponent
      * @return the default instance for the given class. The return value must
      *         not be modified by the caller
      */
-    public <T> T getDefaultInstance(Class<T> instanceClass) {
-        T instance = (T) instanceCache.get(instanceClass);
+    public <T> T getDefaultInstance(AbstractComponent abstractComponent) {
+        // If the root is a @DesignRoot component, it can't use itself as a
+        // reference or the written design will be empty
+
+        // If the root component in some other way initializes itself in the
+        // constructor
+        if (getRootComponent() == abstractComponent
+                && abstractComponent.getClass().isAnnotationPresent(
+                        DesignRoot.class)) {
+            return (T) getDefaultInstance((Class<? extends Component>) abstractComponent
+                    .getClass().getSuperclass());
+        }
+        return (T) getDefaultInstance(abstractComponent.getClass());
+    }
+
+    private Component getDefaultInstance(
+            Class<? extends Component> componentClass) {
+        Component instance = instanceCache.get(componentClass);
         if (instance == null) {
             try {
-                instance = instanceClass.newInstance();
-                instanceCache.put(instanceClass, instance);
+                instance = componentClass.newInstance();
+                instanceCache.put(componentClass, instance);
             } catch (InstantiationException e) {
                 throw new RuntimeException("Could not instantiate "
-                        + instanceClass.getName());
+                        + componentClass.getName());
             } catch (IllegalAccessException e) {
                 throw new RuntimeException("Could not instantiate "
-                        + instanceClass.getName());
+                        + componentClass.getName());
             }
         }
         return instance;
@@ -663,4 +682,30 @@ public class DesignContext implements Serializable {
         }
     }
 
+    /**
+     * Helper method for component write implementors to determine whether their
+     * children should be written out or not
+     * 
+     * @param c
+     *            The component being written
+     * @param defaultC
+     *            The default instance for the component
+     * @return
+     */
+    public boolean shouldWriteChildren(Component c, Component defaultC) {
+        if (c == getRootComponent()) {
+            // The root component should always write its children - otherwise
+            // the result is empty
+            return true;
+        }
+
+        if (defaultC instanceof HasComponents
+                && ((HasComponents) defaultC).iterator().hasNext()) {
+            // Easy version which assumes that this is a custom component if the
+            // constructor adds children
+            return false;
+        }
+
+        return true;
+    }
 }