Add helper for updating the diffstate of a component

Change-Id: I7a7068bd6fcc86a8bbbc8693d8be4a388ce55a25

5 files changed, 43 insertions, 9 deletions

diff --git a/server/src/main/java/com/vaadin/server/AbstractClientConnector.java b/server/src/main/java/com/vaadin/server/AbstractClientConnector.java
index 9f5416968c..32f62edb8e 100644
--- a/server/src/main/java/com/vaadin/server/AbstractClientConnector.java
+++ b/server/src/main/java/com/vaadin/server/AbstractClientConnector.java
@@ -47,6 +47,7 @@ import com.vaadin.ui.LegacyComponent;
 import com.vaadin.ui.UI;
 
 import elemental.json.JsonObject;
+import elemental.json.JsonValue;
 
 /**
  * An abstract base class for ClientConnector implementations. This class
@@ -1083,4 +1084,32 @@ public abstract class AbstractClientConnector
     public int hashCode() {
         return super.hashCode();
     }
+
+    /**
+     * Sets the expected value of a state property so that changes can be
+     * properly sent to the client. This needs to be done in cases where a state
+     * change originates from the client, since otherwise the server-side would
+     * fail to recognize if the value is changed back to its previous value.
+     *
+     * @param propertyName
+     *            the name of the shared state property to update
+     * @param newValue
+     *            the new diffstate reference value
+     */
+    protected void updateDiffstate(String propertyName, JsonValue newValue) {
+        if (!isAttached()) {
+            return;
+        }
+
+        JsonObject diffState = getUI().getConnectorTracker().getDiffState(this);
+        if (diffState == null) {
+            return;
+        }
+
+        assert diffState.hasKey(propertyName) : "Diffstate for "
+                + getClass().getName() + " has no property named "
+                + propertyName;
+
+        diffState.put(propertyName, newValue);
+    }
 }
diff --git a/server/src/main/java/com/vaadin/ui/AbstractTextField.java b/server/src/main/java/com/vaadin/ui/AbstractTextField.java
index 831b0ba6c6..07044bf472 100644
--- a/server/src/main/java/com/vaadin/ui/AbstractTextField.java
+++ b/server/src/main/java/com/vaadin/ui/AbstractTextField.java
@@ -35,6 +35,8 @@ import com.vaadin.shared.ui.textfield.AbstractTextFieldState;
 import com.vaadin.ui.declarative.DesignAttributeHandler;
 import com.vaadin.ui.declarative.DesignContext;
 
+import elemental.json.Json;
+
 /**
  * Abstract base class for text input components.
  *
@@ -49,8 +51,8 @@ public abstract class AbstractTextField extends AbstractField<String>
 
         @Override
         public void setText(String text, int cursorPosition) {
-            getUI().getConnectorTracker().getDiffState(AbstractTextField.this)
-                    .put("text", text);
+            updateDiffstate("text", Json.create(text));
+
             lastKnownCursorPosition = cursorPosition;
             setValue(text, true);
         }
diff --git a/server/src/main/java/com/vaadin/ui/Button.java b/server/src/main/java/com/vaadin/ui/Button.java
index f18ad276d9..4a8e9b4b92 100644
--- a/server/src/main/java/com/vaadin/ui/Button.java
+++ b/server/src/main/java/com/vaadin/ui/Button.java
@@ -38,6 +38,8 @@ import com.vaadin.ui.declarative.DesignContext;
 import com.vaadin.ui.declarative.DesignFormatter;
 import com.vaadin.util.ReflectTools;
 
+import elemental.json.Json;
+
 /**
  * A generic button component.
  *
@@ -61,8 +63,7 @@ public class Button extends AbstractFocusable
             // Makes sure the enabled=false state is noticed at once - otherwise
             // a following setEnabled(true) call might have no effect. see
             // ticket #10030
-            getUI().getConnectorTracker().getDiffState(Button.this)
-                    .put("enabled", false);
+            updateDiffstate("enabled", Json.create(false));
         }
     };
 
diff --git a/server/src/main/java/com/vaadin/ui/RichTextArea.java b/server/src/main/java/com/vaadin/ui/RichTextArea.java
index 96a639e285..44ecb7aae0 100644
--- a/server/src/main/java/com/vaadin/ui/RichTextArea.java
+++ b/server/src/main/java/com/vaadin/ui/RichTextArea.java
@@ -26,6 +26,8 @@ import com.vaadin.shared.ui.richtextarea.RichTextAreaServerRpc;
 import com.vaadin.shared.ui.richtextarea.RichTextAreaState;
 import com.vaadin.ui.declarative.DesignContext;
 
+import elemental.json.Json;
+
 /**
  * A simple RichTextArea to edit HTML format text.
  */
@@ -35,8 +37,7 @@ public class RichTextArea extends AbstractField<String>
     private class RichTextAreaServerRpcImpl implements RichTextAreaServerRpc {
         @Override
         public void setText(String text) {
-            getUI().getConnectorTracker().getDiffState(RichTextArea.this)
-                    .put("value", text);
+            updateDiffstate("value", Json.create(text));
             if (!setValue(text, true)) {
                 // The value was not updated, this could happen if the field has
                 // been set to readonly on the server and the client does not
@@ -106,7 +107,7 @@ public class RichTextArea extends AbstractField<String>
      * Sets the value of this object. If the new value is not equal to
      * {@code getValue()}, fires a {@link ValueChangeEvent}. Throws
      * {@code NullPointerException} if the value is null.
-     * 
+     *
      * @param value
      *            the new value, not {@code null}
      * @throws NullPointerException
diff --git a/server/src/main/java/com/vaadin/ui/Slider.java b/server/src/main/java/com/vaadin/ui/Slider.java
index f6cc37f61a..16c287d92c 100644
--- a/server/src/main/java/com/vaadin/ui/Slider.java
+++ b/server/src/main/java/com/vaadin/ui/Slider.java
@@ -28,6 +28,8 @@ import com.vaadin.shared.ui.slider.SliderState;
 import com.vaadin.ui.declarative.DesignAttributeHandler;
 import com.vaadin.ui.declarative.DesignContext;
 
+import elemental.json.Json;
+
 /**
  * A component for selecting a numerical value within a range.
  *
@@ -45,8 +47,7 @@ public class Slider extends AbstractField<Double> {
          *
          * See #12133.
          */
-        getUI().getConnectorTracker().getDiffState(Slider.this).put("value",
-                value);
+        updateDiffstate("value", Json.create(value));
 
         try {
             setValue(value, true);