fix(esf): improve how column values are generated

Author: onlyexeption

projects/igniteui-angular/src/lib/grids/filtering/excel-style/grid.excel-style-filtering.component.ts

@@ -494,7 +494,15 @@ export class IgxGridExcelStyleFilteringComponent implements OnDestroy {
     }
 
     private generateUniqueValues(columnValues: any[]) {
-        this.uniqueValues = Array.from(new Set(columnValues));
+        if (this.column.dataType === DataType.String && this.column.filteringIgnoreCase) {
+            const filteredUniqueValues = columnValues.map(s => s?.toLowerCase())
+                .reduce((map, val, i) => map.get(val) ? map : map.set(val, columnValues[i]),
+                new Map);
+
+            this.uniqueValues = Array.from(filteredUniqueValues.values());
+        } else {
+            this.uniqueValues = Array.from(new Set(columnValues));
+        }
     }
 
     private generateFilterValues(isDateColumn: boolean = false) {
@@ -599,13 +607,6 @@ export class IgxGridExcelStyleFilteringComponent implements OnDestroy {
 
         this.uniqueValues.forEach(element => {
             if (element !== undefined && element !== null && element !== '') {
-                if (this.column.dataType === DataType.String &&
-                    this.column.filteringIgnoreCase &&
-                    this.listData.length > 0 &&
-                    this.listData.map(el => el.label.toLowerCase()).indexOf(element.toLowerCase()) !== -1) {
-                        return;
-                    }
-
                 const filterListItem = new FilterListItem();
                 if (this.column.filteringExpressionsTree) {
                     if (shouldUpdateSelection) {

projects/igniteui-angular/src/lib/grids/grid/grid-filtering-ui.spec.ts

@@ -4355,7 +4355,9 @@ describe('IgxGrid - Filtering actions - Excel style filtering #grid', () => {
 
             const searchComponent = GridFunctions.getExcelStyleSearchComponent(fix);
             const listItems = GridFunctions.getExcelStyleSearchComponentListItems(fix, searchComponent);
+
             expect(listItems.length).toBe(3, 'incorrect rendered list items count');
+            expect(listItems[1].innerText).toBe('Custom', 'incorrect list item label');
         }));
 
         it('Should not ignore duplicate records when column\'\s filteringIgnoreCase is false', fakeAsync(() => {
@@ -4369,7 +4371,11 @@ describe('IgxGrid - Filtering actions - Excel style filtering #grid', () => {
 
             const searchComponent = GridFunctions.getExcelStyleSearchComponent(fix);
             const listItems = GridFunctions.getExcelStyleSearchComponentListItems(fix, searchComponent);
+
             expect(listItems.length).toBe(5, 'incorrect rendered list items count');
+            expect(listItems[1].innerText).toBe('Custom', 'incorrect list item label');
+            expect(listItems[3].innerText).toBe('custoM', 'incorrect list item label');
+            expect(listItems[4].innerText).toBe('custom', 'incorrect list item label');
         }));
     });