DataGrid - Selected (Blanks) in the header filter should be applied if the Filter Row and Filter Panel is visible

e2e/testcafe-devextreme/tests/dataGrid/headerFilter/headerFilter.ts

@@ -10,6 +10,46 @@ fixture.disablePageReloads`Header Filter`
 
 const GRID_CONTAINER = '#container';
 
+test('Data should be filtered if (Blank) is selected in the header filter (T1257261)', async (t) => {
+  const result: string[] = [];
+  const dataGrid = new DataGrid(GRID_CONTAINER);
+  const headerCell = dataGrid.getHeaders().getHeaderRow(0).getHeaderCell(1);
+  const dataCell = dataGrid.getDataRow(0).getDataCell(0);
+  const filterIconElement = headerCell.getFilterIcon();
+  const headerFilter = new HeaderFilter();
+  const buttons = headerFilter.getButtons();
+  const list = headerFilter.getList();
+
+  await t.click(filterIconElement)
+    .click(list.getItem(1).element)
+    .click(buttons.nth(0));
+
+  result[0] = await dataCell.element().innerText;
+
+  await t.click(filterIconElement)
+    .click(filterIconElement)
+    .click(list.getItem(1).element)
+    .click(list.getItem(0).element)
+    .click(buttons.nth(0));
+
+  result[1] = await dataCell.element().innerText;
+
+  await t.expect(result[0]).eql('1')
+    .expect(result[1]).eql('2');
+}).before(async () => createWidget('dxDataGrid', {
+  dataSource: [
+    { ID: 1, Text: 'Item 1' },
+    { ID: 2, Text: '' },
+    { ID: 3, Text: 'Item 3' },
+  ],
+  keyExpr: 'ID',
+  showBorders: true,
+  remoteOperations: true,
+  headerFilter: { visible: true },
+  filterRow: { visible: true },
+  filterPanel: { visible: true },
+}));
+
 test('HeaderFilter icon should be grayed out after the clearFilter call (T1193648)', async (t) => {
   const { takeScreenshot, compareResults } = createScreenshotsComparer(t);
   const dataGrid = new DataGrid(GRID_CONTAINER);

packages/devextreme/js/__internal/grids/grid_core/filter/m_filter_row.ts

@@ -162,7 +162,7 @@ const normalizeFilterValue = function (that, filterValue, column, $editorContain
 };
 
 const updateFilterValue = function (that, options) {
-  const value = options.value === '' ? null : options.value;
+  const { value } = options;
   const $editorContainer = options.container;
   const column = that._columnsController.columnOption(options.column.index);
   const filterValue = getFilterValue(that, column.index, $editorContainer);