UiPreferences: improve applying column preferences

When the column preferences are applied the column is updated directly,
but some preferences can only be applied if the column is of a specific
type (e.g. NumberColumn). If there are preferences set for these cases
the preferences are lost. Normally this is ok, because the column can
not handle these preferences, but it makes it impossible to e.g. use
placeholder columns if the real column can only be created
asynchronously. Therefore, introduce the interface
ColumnPreferencesColumn which contains a getter and a setter for the
whole preferences. If preferences are applied to such a column the whole
TableColumnClientUiPreferenceDo is passed to the setter and later on
these preferences are used as a fallback for preference values that can
only be extracted from specific column types when the preferences are
stored.

449721

Author: fschinkel

eclipse-scout-core/src/prefs/TableUiPreferences.ts

@@ -256,8 +256,16 @@ export class TableUiPreferences implements ObjectWithType {
           sortOrder: column.sortIndex,
           sortAscending: column.sortAscending,
           groupingActive: column.grouped,
-          aggregationFunctionId: column instanceof NumberColumn ? column.aggregationFunction : undefined,
-          backgroundEffectId: column instanceof NumberColumn ? column.backgroundEffect : undefined
+          aggregationFunctionId: column instanceof NumberColumn
+            ? column.aggregationFunction
+            : this.isColumnPreferencesColumn(column)
+              ? column.getColumnPreferences()?.aggregationFunctionId
+              : undefined,
+          backgroundEffectId: column instanceof NumberColumn
+            ? column.backgroundEffect
+            : this.isColumnPreferencesColumn(column)
+              ? column.getColumnPreferences()?.backgroundEffectId
+              : undefined
         });
       });
   }
@@ -510,13 +518,21 @@ export class TableUiPreferences implements ObjectWithType {
       column.setAggregationFunction(columnPreferences.aggregationFunctionId as NumberColumnAggregationFunction);
       column.setBackgroundEffect(columnPreferences.backgroundEffectId as NumberColumnBackgroundEffect, false); // false = don't redraw
     }
+
+    if (this.isColumnPreferencesColumn(column)) {
+      column.setColumnPreferences(columnPreferences);
+    }
   }
 
   protected _applyUserFilterStates(table: Table, userFilterStates: IUserFilterStateDo[], options?: ApplyTablePreferencesOptions) {
     if (options?.applyUserFilters) { // true when showing a bookmark
       table.applyUserFilterStates(userFilterStates);
     }
   }
+
+  isColumnPreferencesColumn<TValue>(column: Column<TValue> & Partial<Omit<ColumnPreferencesColumn<TValue>, keyof Column<TValue>>>): column is ColumnPreferencesColumn<TValue> {
+    return objects.isFunction(column?.getColumnPreferences) && objects.isFunction(column.setColumnPreferences);
+  }
 }
 
 // --------------------------------------
@@ -571,3 +587,16 @@ UiPreferences.registerHandler(TableUiPreferences, {
     preferences.tablePreferences = tableUiPreferences._exportTablePreferences();
   }
 });
+
+/**
+ * Interface for {@link Column}s containing a getter and a setter for {@link TableColumnClientUiPreferenceDo}.
+ * When preferences are applied to such a {@link Column} the whole {@link TableColumnClientUiPreferenceDo} is passed to the setter.
+ * Later on these preferences are used as a fallback for preference values that can only be extracted from
+ * specific column types (e.g. {@link NumberColumn#aggregationFunction} or {@link NumberColumn#backgroundEffect}) when the preferences are stored.
+ *
+ * With this one can e.g. implement placeholder columns that cache the preferences while the real columns are created asynchronously.
+ */
+export interface ColumnPreferencesColumn<TValue = any> extends Column<TValue> {
+  getColumnPreferences: () => TableColumnClientUiPreferenceDo;
+  setColumnPreferences: (columnPreferences: TableColumnClientUiPreferenceDo) => void;
+}