DxTreeList.GetColumns() Method
Returns a collection of all treelist columns.
Namespace: DevExpress.Blazor
Assembly: DevExpress.Blazor.v24.2.dll
NuGet Package: DevExpress.Blazor
Declaration
public IReadOnlyList<ITreeListColumn> GetColumns()Returns
| Type | Description |
|---|---|
| IReadOnlyList<ITreeListColumn> | The column collection. |
Remarks
Call the TreeList’s GetVisibleColumns() method to get a collection of visible columns sorted based on their display order. To get a collection of all treelist columns, call the GetColumns method. Whenever these methods encounter a band, they include it followed by all its nested columns in the collection. If nested bands exist, the methods add them and their nested columns recursively.
The GetDataColumns() method allows you to get a collection of data columns.
The following code snippet shows the difference between the results of the GetColumns and GetVisibleColumns methods.
@inject EmployeeTaskService EmployeeTaskService
<style>
.my-button {
width: 150px;
margin-bottom: 5px;
margin-top: 5px;
}
</style>
<DxTreeList @ref="@TreeList"
Data="TreeListData"
KeyFieldName="Id"
ParentKeyFieldName="ParentId"
@bind-SelectedDataItems="@SelectedDataItems">
<Columns>
<DxTreeListDataColumn FieldName="EmployeeName" VisibleIndex="2" />
<DxTreeListDataColumn FieldName="Name" VisibleIndex="1" />
<DxTreeListDataColumn FieldName="StartDate" />
<DxTreeListDataColumn FieldName="DueDate" />
<DxTreeListSelectionColumn VisibleIndex="0" Width="50"/>
</Columns>
</DxTreeList>
<DxButton Click="@OnGetColumns" CssClass="my-button" Text="Get Columns" />
<DxButton Click="@OnGetVisibleColumns" CssClass="my-button" Text="Get Visible Columns" />
<div><b>Columns</b>: @ColumnInfo</div>
<div><b>Visible Columns</b>: @VisibleColumnInfo</div>
@code {
List<EmployeeTask> TreeListData { get; set; }
ITreeList TreeList { get; set; }
string ColumnInfo { get; set; }
string VisibleColumnInfo { get; set; }
IReadOnlyList<object> SelectedDataItems { get; set; }
protected override void OnInitialized() {
TreeListData = EmployeeTaskService.GenerateData();
}
void OnGetColumns() {
ColumnInfo = GetColumnInfo(TreeList.GetColumns());
}
void OnGetVisibleColumns() {
VisibleColumnInfo = GetColumnInfo(TreeList.GetVisibleColumns());
}
string GetColumnInfo(IEnumerable<ITreeListColumn> columns) {
var columnInfo = columns.Select((column, index) => (1 + index) + " - " + column switch {
ITreeListDataColumn dataColumn => dataColumn.FieldName,
ITreeListSelectionColumn => "Selection Column",
_ => null
});
return string.Join("; ", columnInfo);
}
}
