Enable setting non-selected default value for DateField (#9745)

Requested feature: allow setting DateField to a certain starting point without selecting a value.

3 files changed, 61 insertions, 0 deletions

diff --git a/client/src/main/java/com/vaadin/client/ui/VAbstractPopupCalendar.java b/client/src/main/java/com/vaadin/client/ui/VAbstractPopupCalendar.java
index a8c356a07c..9d9862ceae 100644
--- a/client/src/main/java/com/vaadin/client/ui/VAbstractPopupCalendar.java
+++ b/client/src/main/java/com/vaadin/client/ui/VAbstractPopupCalendar.java
@@ -391,6 +391,8 @@ public abstract class VAbstractPopupCalendar<PANEL extends VAbstractCalendarPane
 
             if (getCurrentDate() != null) {
                 calendar.setDate((Date) getCurrentDate().clone());
+            } else if (getDefaultDate() != null) {
+                calendar.setDate(getDefaultDate());
             } else {
                 calendar.setDate(new Date());
             }
diff --git a/client/src/main/java/com/vaadin/client/ui/VDateField.java b/client/src/main/java/com/vaadin/client/ui/VDateField.java
index 40fc9a8f8c..772f72c897 100644
--- a/client/src/main/java/com/vaadin/client/ui/VDateField.java
+++ b/client/src/main/java/com/vaadin/client/ui/VDateField.java
@@ -54,6 +54,12 @@ public abstract class VDateField<R extends Enum<R>> extends FlowPanel
     protected boolean enabled;
 
     /**
+     * The date that is displayed the date field before a value is selected. If
+     * null, display the current date.
+     */
+    private Date defaultDate = null;
+
+    /**
      * The date that is selected in the date field. Null if an invalid date is
      * specified.
      */
@@ -95,6 +101,18 @@ public abstract class VDateField<R extends Enum<R>> extends FlowPanel
     }
 
     /**
+     * Set the default date to open popup when no date is selected.
+     *
+     * @param date
+     *            default date to show as the initial (non-selected) value when
+     *            opening a popup with no value selected
+     * @since 8.1.2
+     */
+    public void setDefaultDate(Date date) {
+        this.defaultDate = date;
+    }
+
+    /**
      * Set the current date using a map with date values.
      * <p>
      * The map contains integer representation of values per resolution. The
@@ -108,6 +126,27 @@ public abstract class VDateField<R extends Enum<R>> extends FlowPanel
         setCurrentDate(getDate(dateValues));
     }
 
+    /**
+     * Set the default date using a map with date values.
+     *
+     * @see #setCurrentDate(Map)
+     * @param defaultValues
+     * @since 8.1.2
+     */
+    public void setDefaultDate(Map<R, Integer> defaultValues) {
+        setDefaultDate(getDate(defaultValues));
+    }
+
+    /**
+     * Sets the default date when no date is selected.
+     *
+     * @return the default date
+     * @since 8.1.2
+     */
+    public Date getDefaultDate() {
+        return defaultDate;
+    }
+
     public boolean isReadonly() {
         return readonly;
     }
diff --git a/client/src/main/java/com/vaadin/client/ui/datefield/AbstractDateFieldConnector.java b/client/src/main/java/com/vaadin/client/ui/datefield/AbstractDateFieldConnector.java
index c851c13679..21e85773de 100644
--- a/client/src/main/java/com/vaadin/client/ui/datefield/AbstractDateFieldConnector.java
+++ b/client/src/main/java/com/vaadin/client/ui/datefield/AbstractDateFieldConnector.java
@@ -77,6 +77,7 @@ public abstract class AbstractDateFieldConnector<R extends Enum<R>>
                 + getWidget().resolutionAsString(), true);
 
         getWidget().setCurrentDate(getTimeValues(uidl));
+        getWidget().setDefaultDate(getDefaultValues(uidl));
     }
 
     private void updateResolution(UIDL uidl) {
@@ -98,6 +99,25 @@ public abstract class AbstractDateFieldConnector<R extends Enum<R>>
                                 : -1));
     }
 
+    /**
+     * Returns the default date (when no date is selected) components as a map
+     * from Resolution to the corresponding value.
+     * 
+     * @param uidl
+     *            UIDL with corresponding variables
+     * @return default date component map
+     * @since 8.1.2
+     */
+    protected Map<R, Integer> getDefaultValues(UIDL uidl) {
+        Stream<R> resolutions = getWidget().getResolutions();
+        R resolution = getWidget().getCurrentResolution();
+        return resolutions.collect(Collectors.toMap(Function.identity(),
+                res -> (resolution.compareTo(res) <= 0)
+                        ? uidl.getIntVariable("default-"
+                                + getWidget().getResolutionVariable(res))
+                        : -1));
+    }
+
     @SuppressWarnings("unchecked")
     @Override
     public VDateField<R> getWidget() {