Add lockedRowCount property into matrix dynamic fix #8070

src/question_matrixdropdownrendered.ts

@@ -551,7 +551,8 @@ export class QuestionMatrixDropdownRenderedTable extends Base {
   }
   private getRowDragCell(rowIndex: number) {
     const cell = new QuestionMatrixDropdownRenderedCell();
-    cell.isDragHandlerCell = true;
+    const lockedRows = (<QuestionMatrixDynamicModel>this.matrix).lockedRowCount;
+    cell.isDragHandlerCell = lockedRows < 1 || rowIndex >= lockedRows;
     cell.className = this.getActionsCellClassName(cell);
     cell.row = this.matrix.visibleRows[rowIndex];
     return cell;

src/question_matrixdynamic.ts

@@ -84,12 +84,12 @@ export class QuestionMatrixDynamicModel extends QuestionMatrixDropdownModelBase
         this.updateShowTableAndAddRow();
       }
     );
-    this.registerPropertyChangedHandlers(["allowRowsDragAndDrop", "isReadOnly"], () => { this.clearRowsAndResetRenderedTable(); });
+    this.registerPropertyChangedHandlers(["allowRowsDragAndDrop", "isReadOnly", "lockedRowCount"], () => { this.clearRowsAndResetRenderedTable(); });
     this.dragOrClickHelper = new DragOrClickHelper(this.startDragMatrixRow);
   }
 
   public dragDropMatrixRows: DragDropMatrixRows;
-  public setSurveyImpl(value: ISurveyImpl, isLight?: boolean) {
+  public setSurveyImpl(value: ISurveyImpl, isLight?: boolean): void {
     super.setSurveyImpl(value, isLight);
     this.dragDropMatrixRows = new DragDropMatrixRows(this.survey, null, true);
   }
@@ -283,6 +283,12 @@ export class QuestionMatrixDynamicModel extends QuestionMatrixDropdownModelBase
   public get isRowsDragAndDrop(): boolean {
     return this.allowRowsDragAndDrop && !this.isReadOnly;
   }
+  public get lockedRowCount(): number {
+    return this.getPropertyValue("lockedRowCount", 0);
+  }
+  public set lockedRowCount(val: number) {
+    this.setPropertyValue("lockedRowCount", val);
+  }
 
   public get iconDragElement(): string {
     return this.cssClasses.iconDragElement;
@@ -407,11 +413,9 @@ export class QuestionMatrixDynamicModel extends QuestionMatrixDropdownModelBase
   }
   public canRemoveRow(row: MatrixDropdownRowModelBase): boolean {
     if (!this.survey) return true;
-    return this.survey.matrixAllowRemoveRow(
-      this,
-      (<MatrixDynamicRowModel>row).index,
-      row
-    );
+    const index = (<MatrixDynamicRowModel>row).index;
+    if(this.lockedRowCount > 0 && index < this.lockedRowCount) return false;
+    return this.survey.matrixAllowRemoveRow(this, index, row);
   }
   public addRowUI(): void {
     this.addRow(true);

tests/question_matrixdynamictests.ts

@@ -9235,4 +9235,31 @@ QUnit.test("Totals alingment", function (assert) {
     renderedTable.footerRow.cells[3].cellQuestionWrapperClassName,
     "sd-table__question-wrapper sd-table__question-wrapper--expression sd-table__question-wrapper--center"
   );
-});
+});
+QUnit.test("lockedRowCount property", function (assert) {
+  var survey = new SurveyModel({
+    elements: [
+      {
+        type: "matrixdynamic",
+        name: "matrix",
+        allowRowsDragAndDrop: true,
+        rowCount: 4,
+        columns: ["col1"]
+      }
+    ]
+  });
+  const matrix = <QuestionMatrixDynamicModel>survey.getQuestionByName("matrix");
+  matrix.lockedRowCount = 2;
+  const rows = matrix.visibleRows;
+  assert.equal(matrix.canRemoveRow(rows[0]), false, "canRemoveRow, row#0");
+  assert.equal(matrix.canRemoveRow(rows[1]), false, "canRemoveRow, row#1");
+  assert.equal(matrix.canRemoveRow(rows[2]), true, "canRemoveRow, row#2");
+  assert.equal(matrix.canRemoveRow(rows[3]), true, "canRemoveRow, row#3");
+
+  const table = matrix.renderedTable;
+  assert.equal(table.headerRow.cells.length, 3, "Drag handler cell + one column + actions cell");
+  assert.equal(table.rows[1].cells[0].isDragHandlerCell, false, "isDragHandlerCell, row#1");
+  assert.equal(table.rows[3].cells[0].isDragHandlerCell, false, "isDragHandlerCell, row#2");
+  assert.equal(table.rows[5].cells[0].isDragHandlerCell, true, "isDragHandlerCell, row#3");
+  assert.equal(table.rows[7].cells[0].isDragHandlerCell, true, "isDragHandlerCell, row#4");
+});