Disable export action when no valueContext is available (no item sele…

…cted)

src/main/java/com/namics/oss/magnolia/appbuilder/action/importexport/ExportAppActionDefinition.java

@@ -8,6 +8,7 @@
 import com.namics.oss.magnolia.appbuilder.MgnlIcon;
 import com.namics.oss.magnolia.appbuilder.action.AppActionDefinition;
 import com.namics.oss.magnolia.appbuilder.action.AvailabilityDefinitionBuilder;
+import com.namics.oss.magnolia.appbuilder.action.rule.HasValueContextRule;
 import com.namics.oss.magnolia.appbuilder.action.rule.JcrIsNotDeletedRuleDefinition;
 import com.namics.oss.magnolia.appbuilder.action.rule.PermissionRequiredRuleDefinition;
 
@@ -21,6 +22,7 @@ public ConfiguredActionDefinition action() {
 		definition.setIcon(MgnlIcon.EXPORT);
 		definition.setLabel("actions.export");
 		definition.setAvailability(new AvailabilityDefinitionBuilder()
+				.rule(new HasValueContextRule.Definition())
 				.rule(new JcrIsNotDeletedRuleDefinition())
 				.rule(new PermissionRequiredRuleDefinition(Permission.READ))
 				.build()

src/main/java/com/namics/oss/magnolia/appbuilder/action/rule/HasValueContextRule.java

@@ -0,0 +1,31 @@
+package com.namics.oss.magnolia.appbuilder.action.rule;
+
+import info.magnolia.ui.ValueContext;
+import info.magnolia.ui.api.availability.AvailabilityRule;
+import info.magnolia.ui.api.availability.AvailabilityRuleType;
+import info.magnolia.ui.api.availability.ConfiguredAvailabilityRuleDefinition;
+
+import java.util.Collection;
+
+import javax.inject.Inject;
+
+public class HasValueContextRule implements AvailabilityRule {
+    private final ValueContext<?> valueContext;
+
+    @Inject
+    public HasValueContextRule(final ValueContext<?> valueContext) {
+        this.valueContext = valueContext;
+    }
+
+    @Override
+    public boolean isAvailable(final Collection<?> itemIds) {
+        return valueContext.getSingle().isPresent();
+    }
+
+    @AvailabilityRuleType("hasValueContextRule")
+    public static class Definition extends ConfiguredAvailabilityRuleDefinition {
+        public Definition() {
+            setImplementationClass(HasValueContextRule.class);
+        }
+    }
+}