DxTreeList.EditStart Event
Fires before the TreeList starts editing a row.
Namespace: DevExpress.Blazor
Assembly: DevExpress.Blazor.v24.2.dll
NuGet Package: DevExpress.Blazor
Declaration
[Parameter]
public EventCallback<TreeListEditStartEventArgs> EditStart { get; set; }Parameters
| Type | Description |
|---|---|
| TreeListEditStartEventArgs | An object that contains data for this event. |
Remarks
The EditStart event occurs in the following cases:
- A user clicks the New or Edit button in the command column.
- A user clicks the new item row or focuses it and presses Enter.
- In EditCell mode, a user clicks a data cell in a row that is in display mode or focuses this cell and presses Enter.
- The StartEditRowAsync or StartEditNewRowAsync method is called.
Handle this event to create a custom response to the edit start action. Use the IsNew event argument to identify whether a new or existing data item is about to be edited. DataItem and ParentDataItem properties return the processed data item and its parent. The TreeList property allows you to access the TreeList and its extensive API.
You can set the Cancel event argument to true to prevent users from editing specific rows. The following code snippet prevents users from editing unselected rows:
@inject EmployeeTaskService EmployeeTaskService
<DxTreeList Data="TreeListData"
KeyFieldName="Id"
ParentKeyFieldName="ParentId"
EditModelSaving="TreeList_EditModelSaving"
CustomizeEditModel="TreeList_CustomizeEditModel"
AllowSelectRowByClick="true"
SelectionMode="TreeListSelectionMode.Single"
@bind-SelectedDataItem="@SelectedDataItem"
EditStart="TreeList_EditStart">
<Columns>
<DxTreeListCommandColumn DeleteButtonVisible="false" />
<DxTreeListDataColumn FieldName="Name" Caption="Task" />
<DxTreeListDataColumn FieldName="EmployeeName" />
<DxTreeListDataColumn FieldName="StartDate" />
<DxTreeListDataColumn FieldName="DueDate" />
</Columns>
</DxTreeList>
@code {
List<EmployeeTask> TreeListData { get; set; }
object SelectedDataItem { get; set; }
protected override void OnInitialized() {
TreeListData = EmployeeTaskService.GenerateData();
}
async Task TreeList_EditStart(TreeListEditStartEventArgs e) {
if (!e.IsNew && !e.TreeList.IsDataItemSelected(e.DataItem))
e.Cancel = true;
}
void TreeList_CustomizeEditModel(TreeListCustomizeEditModelEventArgs e) {
if(e.IsNew) {
var newTask = (EmployeeTask)e.EditModel;
newTask.Id = TreeListData.Max(x => x.Id) + 1;
if(e.ParentDataItem != null)
newTask.ParentId = ((EmployeeTask)e.ParentDataItem).Id;
}
}
async Task TreeList_EditModelSaving(TreeListEditModelSavingEventArgs e) {
if(e.IsNew)
TreeListData.Add((EmployeeTask)e.EditModel);
else
e.CopyChangesToDataItem();
}
}
Refer to the following topic for more information: Editing and Validation in Blazor TreeList.