fix: export with hidden columns fixed [T1307282]

packages/devextreme/js/ui/gantt/ui.gantt.export_helper.js

@@ -144,7 +144,7 @@ export class GanttExportHelper {
         return task && this._getGridDisplayText(colIndex, task);
     }
     _getGridDisplayText(colIndex, data) {
-        const columns = this._treeList.getController('columns').getColumns();
+        const columns = this._treeList.getController('columns').getVisibleColumns();
         const column = columns[colIndex];
         const field = column?.dataField;
         const format = column?.format;

packages/devextreme/testing/tests/DevExpress.ui.widgets/gantt.tests.js

@@ -33,6 +33,7 @@ import './ganttParts/treeListExpanding.tests.js';
 import './ganttParts/scrolling.tests.js';
 import './ganttParts/selection.tests.js';
 import './ganttParts/milestone.tests.js';
+import './ganttParts/exportHelper.tests.js';
 
 QUnit.testStart(() => {
     const markup = '<div id="gantt"></div>';

packages/devextreme/testing/tests/DevExpress.ui.widgets/ganttParts/exportHelper.tests.js

@@ -0,0 +1,53 @@
+import { GanttExportHelper } from 'ui/gantt/ui.gantt.export_helper';
+import gridCoreUtils from '__internal/grids/grid_core/m_utils';
+
+const moduleConfig = {
+    beforeEach: function() {
+        this.calledColumns = [];
+        this.getDisplayValueStub = sinon.stub(gridCoreUtils, 'getDisplayValue').callsFake((column, rawValue) => {
+            this.calledColumns.push(column && column.dataField);
+            return rawValue;
+        });
+    },
+    afterEach: function() {
+        this.getDisplayValueStub.restore();
+    }
+};
+
+QUnit.module('GanttExportHelper', moduleConfig);
+
+QUnit.test('getGridDisplayText uses only visible columns (T1307282)', function(assert) {
+    const visibleColumns = [
+        { dataField: 'id', dataType: 'number' },
+        { dataField: 'title', dataType: 'string' }
+    ];
+
+    const hiddenColumn = {
+        dataField: 'secret',
+        dataType: 'string',
+    };
+
+    const treeListStub = {
+        getController: function() {
+            return {
+                getVisibleColumns: function() {
+                    return visibleColumns;
+                },
+                getColumns: function() {
+                    return [...visibleColumns, hiddenColumn];
+                }
+            };
+        }
+    };
+
+    const helper = new GanttExportHelper({ _treeList: treeListStub });
+    const data = { id: 1, title: 'Task A', secret: 'hidden' };
+
+    assert.strictEqual(helper._getGridDisplayText(0, data), '1', 'First visible column value returned');
+    assert.strictEqual(helper._getGridDisplayText(1, data), 'Task A', 'Second visible column value returned');
+
+    assert.strictEqual(helper._getGridDisplayText(2, data), undefined, 'Out-of-range visible column index returns undefined');
+
+    assert.deepEqual(this.calledColumns, ['id', 'title', undefined], 'Only visible columns (and undefined for out-of-range) were queried');
+    assert.notOk(this.calledColumns.includes('secret'), 'Hidden column was not accessed');
+});