PL-7324 Add an ability to disable null option for components with lookup action

modules/desktop/src/com/haulmont/cuba/desktop/gui/components/DesktopLookupField.java

@@ -76,6 +76,8 @@ public class DesktopLookupField extends DesktopAbstractOptionsField<JComponent>
     protected String inputPrompt;
     protected boolean textInputAllowed = true;
 
+    protected boolean nullOptionVisible = true;
+
     protected List<UserSelectionListener> userSelectionListeners = null; // lazy initialized list
 
     public DesktopLookupField() {
@@ -300,7 +302,7 @@ public class DesktopLookupField extends DesktopAbstractOptionsField<JComponent>
 
         items.clear();
 
-        if (!isRequired() && nullOption == null) {
+        if (!isRequired() && nullOption == null && nullOptionVisible) {
             items.add(new ObjectWrapper(null));
         }
 
@@ -414,6 +416,16 @@ public class DesktopLookupField extends DesktopAbstractOptionsField<JComponent>
         // do nothing
     }
 
+    @Override
+    public void setNullOptionVisible(boolean nullOptionVisible) {
+        this.nullOptionVisible = nullOptionVisible;
+    }
+
+    @Override
+    public boolean isNullOptionVisible() {
+        return nullOptionVisible;
+    }
+
     @Override
     public String getInputPrompt() {
         return inputPrompt;

modules/desktop/src/com/haulmont/cuba/desktop/gui/components/DesktopSearchField.java

@@ -75,6 +75,8 @@ public class DesktopSearchField extends DesktopAbstractOptionsField<JComponent>
 
     protected int minSearchStringLength = 0;
 
+    protected boolean nullOptionVisible = true;
+
     protected Frame.NotificationType defaultNotificationType = Frame.NotificationType.TRAY;
 
     protected Color searchEditBgColor = (Color) UIManager.get("cubaSearchEditBackground");
@@ -450,6 +452,16 @@ public class DesktopSearchField extends DesktopAbstractOptionsField<JComponent>
         // do nothing
     }
 
+    @Override
+    public void setNullOptionVisible(boolean nullOptionVisible) {
+        this.nullOptionVisible = nullOptionVisible;
+    }
+
+    @Override
+    public boolean isNullOptionVisible() {
+        return nullOptionVisible;
+    }
+
     @Override
     public String getInputPrompt() {
         return inputPrompt;

modules/desktop/src/com/haulmont/cuba/desktop/gui/components/DesktopSuggestionField.java

@@ -90,6 +90,7 @@ public class DesktopSuggestionField extends DesktopAbstractOptionsField<JCompone
 
     protected String inputPrompt;
     protected String currentSearchComponentText;
+    protected boolean nullOptionVisible = true;
     private ArrowDownActionHandler arrowDownActionHandler;
 
     public DesktopSuggestionField() {
@@ -532,6 +533,16 @@ public class DesktopSuggestionField extends DesktopAbstractOptionsField<JCompone
         // do nothing
     }
 
+    @Override
+    public void setNullOptionVisible(boolean nullOptionVisible) {
+        this.nullOptionVisible = nullOptionVisible;
+    }
+
+    @Override
+    public boolean isNullOptionVisible() {
+        return nullOptionVisible;
+    }
+
     @Override
     public String getInputPrompt() {
         return inputPrompt;

modules/gui/src/com/haulmont/cuba/gui/components/LookupField.java

@@ -70,6 +70,15 @@ public interface LookupField extends OptionsField, Component.HasInputPrompt {
      */
     void setPageLength(int pageLength);
 
+    /**
+     * Sets visibility for first null element in suggestion popup.
+     */
+    void setNullOptionVisible(boolean nullOptionVisible);
+    /**
+     * @return true if first null element is visible.
+     */
+    boolean isNullOptionVisible();
+
     enum FilterMode {
         NO,
         STARTS_WITH,

modules/gui/src/com/haulmont/cuba/gui/window.xsd

@@ -777,6 +777,7 @@
 
                 <xs:attribute name="newOptionAllowed" type="xs:boolean"/>
                 <xs:attribute name="textInputAllowed" type="xs:boolean"/>
+                <xs:attribute name="nullOptionVisible" type="xs:boolean"/>
                 <xs:attribute name="newOptionHandler" type="xs:string"/>
                 <xs:attribute name="inputPrompt" type="resourceString"/>
             </xs:extension>
@@ -832,6 +833,7 @@
                 <xs:attributeGroup ref="hasOptions"/>
                 <xs:attributeGroup ref="hasCaptionSource"/>
 
+                <xs:attribute name="nullOptionVisible" type="xs:boolean"/>
                 <xs:attribute name="filterMode" type="filterMode"/>
                 <xs:attribute name="nullName" type="resourceString"/>
                 <xs:attribute name="metaClass" type="xs:string"/>

modules/gui/src/com/haulmont/cuba/gui/xml/layout/loaders/LookupFieldLoader.java

@@ -64,6 +64,15 @@ public class LookupFieldLoader extends AbstractFieldLoader<LookupField> {
 
         loadFilterMode(resultComponent, element);
         loadNewOptionHandler(resultComponent, element);
+
+        loadNullOptionVisible(resultComponent, element);
+    }
+
+    protected void loadNullOptionVisible(LookupField resultComponent, Element element) {
+        String nullOptionVisible = element.attributeValue("nullOptionVisible");
+        if (StringUtils.isNotEmpty(nullOptionVisible)) {
+            resultComponent.setNullOptionVisible(Boolean.parseBoolean(nullOptionVisible));
+        }
     }
 
     protected void loadTextInputAllowed() {

modules/web/src/com/haulmont/cuba/web/gui/components/WebLookupField.java

@@ -60,6 +60,8 @@ public class WebLookupField extends WebAbstractOptionsField<CubaComboBox> implem
 
     protected Messages messages = AppBeans.get(Messages.NAME);
 
+    protected boolean nullOptionVisible = true;
+
     public WebLookupField() {
         createComponent();
 
@@ -175,7 +177,8 @@ public class WebLookupField extends WebAbstractOptionsField<CubaComboBox> implem
     @Override
     public void setRequired(boolean required) {
         super.setRequired(required);
-        component.setNullSelectionAllowed(!required);
+
+        component.setNullSelectionAllowed(!required && nullOptionVisible);
     }
 
     @Override
@@ -342,6 +345,17 @@ public class WebLookupField extends WebAbstractOptionsField<CubaComboBox> implem
         component.setPageLength(pageLength);
     }
 
+    @Override
+    public void setNullOptionVisible(boolean nullOptionVisible) {
+        this.nullOptionVisible = nullOptionVisible;
+        component.setNullSelectionAllowed(!isRequired() && nullOptionVisible);
+    }
+
+    @Override
+    public boolean isNullOptionVisible() {
+        return nullOptionVisible;
+    }
+
     @Override
     public String getInputPrompt() {
         return component.getInputPrompt();