11642 refresh pagelength 0 combobox items after dataprovider update (#11653)

* Fixes #11642. ComboBox with pageLength 0 should be updated if DataProvider changes

* added comments, fixed imports

1 files changed, 26 insertions, 5 deletions

diff --git a/server/src/main/java/com/vaadin/ui/ComboBox.java b/server/src/main/java/com/vaadin/ui/ComboBox.java
index c9622e1fd8..b9511450a5 100644
--- a/server/src/main/java/com/vaadin/ui/ComboBox.java
+++ b/server/src/main/java/com/vaadin/ui/ComboBox.java
@@ -28,17 +28,19 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 import java.util.stream.Stream;
 
-import org.jsoup.nodes.Element;
-
-import com.vaadin.data.HasFilterableDataProvider;
-import com.vaadin.data.HasValue;
-import com.vaadin.data.ValueProvider;
 import com.vaadin.data.provider.CallbackDataProvider;
+import com.vaadin.data.provider.DataChangeEvent;
 import com.vaadin.data.provider.DataCommunicator;
 import com.vaadin.data.provider.DataGenerator;
 import com.vaadin.data.provider.DataKeyMapper;
 import com.vaadin.data.provider.DataProvider;
+import com.vaadin.data.provider.InMemoryDataProvider;
 import com.vaadin.data.provider.ListDataProvider;
+import org.jsoup.nodes.Element;
+
+import com.vaadin.data.HasFilterableDataProvider;
+import com.vaadin.data.HasValue;
+import com.vaadin.data.ValueProvider;
 import com.vaadin.event.FieldEvents;
 import com.vaadin.event.FieldEvents.BlurEvent;
 import com.vaadin.event.FieldEvents.BlurListener;
@@ -219,6 +221,11 @@ public class ComboBox<T> extends AbstractSingleSelect<T>
             getState().currentFilterText = filterText;
             filterSlot.accept(filterText);
         }
+
+        @Override
+        public void resetForceDataSourceUpdate() {
+            getState().forceDataSourceUpdate = false;
+        }
     };
 
     /**
@@ -962,6 +969,20 @@ public class ComboBox<T> extends AbstractSingleSelect<T>
 
         filterSlot = filter -> providerFilterSlot
                 .accept(convertOrNull.apply(filter));
+
+        // This workaround is done to fix issue #11642 for unpaged comboboxes.
+        // Data sources for on the client need to be updated after data provider
+        // refreshAll so that serverside selection works even before the dropdown
+        // is opened. Only done for in-memory data providers for performance
+        // reasons.
+        if (dataProvider instanceof InMemoryDataProvider) {
+            dataProvider.addDataProviderListener(event -> {
+                if ((!(event instanceof DataChangeEvent.DataRefreshEvent))
+                        && (getPageLength() == 0)) {
+                    getState().forceDataSourceUpdate = true;
+                }
+            });
+        }
     }
 
     /**