Add value selection(like for month) for custom fields (#11162)

* Add editor class for custom fields to enable value selection from a dropdown

* resolve conflicts with CHANGELOG.md

* fix formatting in FieldEditors and remove contributor name in CHANGELOG

* Update CHANGELOG.md

---------

Co-authored-by: Oliver Kopp <kopp.dev@gmail.com>

CHANGELOG.md

@@ -13,6 +13,7 @@ Note that this project **does not** adhere to [Semantic Versioning](https://semv
 
 - We added support for offline extracting refereferences from PDFs following the IEEE format. [#11156](https://github.com/JabRef/jabref/pull/11156)
 - We added a new keyboard shortcut  <kbd>ctrl</kbd> + <kbd>,</kbd> to open the preferences. [#11154](https://github.com/JabRef/jabref/pull/11154)
+- We added value selection (such as for month) for content selectors in custom entry types. [#11109](https://github.com/JabRef/jabref/issues/11109)
 
 ### Changed
 

src/main/java/org/jabref/gui/fieldeditors/CustomFieldEditorViewModel.java

@@ -0,0 +1,39 @@
+package org.jabref.gui.fieldeditors;
+
+import java.util.List;
+
+import javax.swing.undo.UndoManager;
+
+import org.jabref.gui.autocompleter.SuggestionProvider;
+import org.jabref.logic.integrity.FieldCheckers;
+import org.jabref.model.database.BibDatabaseContext;
+import org.jabref.model.entry.field.Field;
+
+import com.google.common.collect.BiMap;
+import com.google.common.collect.HashBiMap;
+
+public class CustomFieldEditorViewModel extends MapBasedEditorViewModel<String> {
+
+    private BiMap<String, String> itemMap;
+
+    public CustomFieldEditorViewModel(Field field, SuggestionProvider<?> suggestionProvider,
+                                      FieldCheckers fieldCheckers, UndoManager undoManager, BibDatabaseContext databaseContext) {
+        super(field, suggestionProvider, fieldCheckers, undoManager);
+
+        List<String> values = databaseContext.getMetaData().getContentSelectorValuesForField(field);
+        itemMap = HashBiMap.create(values.size());
+        for (String value : values) {
+            itemMap.put(value, value);
+        }
+    }
+
+    @Override
+    protected BiMap<String, String> getItemMap() {
+        return itemMap;
+    }
+
+    @Override
+    public String convertToDisplayText(String object) {
+        return object;
+    }
+}

src/main/java/org/jabref/gui/fieldeditors/FieldEditors.java

@@ -98,6 +98,8 @@ public static FieldEditorFX getForField(final Field field,
             return new CitationKeyEditor(field, suggestionProvider, fieldCheckers, databaseContext);
         } else if (fieldProperties.contains(FieldProperty.MARKDOWN)) {
             return new MarkdownEditor(field, suggestionProvider, fieldCheckers, preferences, undoManager);
+        } else if (fieldProperties.contains(FieldProperty.CUSTOM_FIELD) && !isMultiLine) {
+            return new OptionEditor<>(new CustomFieldEditorViewModel(field, suggestionProvider, fieldCheckers, undoManager, databaseContext));
         } else {
             // default
             return new SimpleEditor(field, suggestionProvider, fieldCheckers, preferences, isMultiLine, undoManager);

src/main/java/org/jabref/model/entry/field/FieldProperty.java

@@ -26,5 +26,6 @@ public enum FieldProperty {
     TYPE,
     VERBATIM,
     YES_NO,
-    COMMENT
+    COMMENT,
+    CUSTOM_FIELD
 }

src/main/java/org/jabref/model/entry/field/UnknownField.java

@@ -32,7 +32,7 @@ public UnknownField(String name, String displayName, FieldProperty first, FieldP
     }
 
     public static UnknownField fromDisplayName(String displayName) {
-        return new UnknownField(displayName.toLowerCase(Locale.ROOT), displayName);
+        return new UnknownField(displayName.toLowerCase(Locale.ROOT), displayName, FieldProperty.CUSTOM_FIELD);
     }
 
     @Override