Selection
RadDataGrid exposes a selection feature - users can select a cell or a row by tapping on it. To cancel the selection, they can simply tap on the cell or a row again. The control provides single and multiple selection.
This article explains the basic properties and methods that RadDataGrid provides for working with selection.
Important Properties
RadDataGrid supports different selection modes that you can modify through the SelectionUnit and SelectedItems properties. Before you can set the SelectionMode, you must choose which Unit can be selected.
SelectionUnit
The SelectionUnit property (type of Telerik.XamarinForms.DataGrid.DataGridSelectionUnit) allows you to control which Unit can be selected:
- Row: The unit to select is a grid row (by default).
- Cell: The unit to select is a cell within a grid row.
To define a Cell when using a selection, you can use the DataGridCellInfo class that holds all the information about the Cell. To define a Row when using a selection, you can use your data object.
The example below shows how to set SelectionUnit in XAML and code-behind:
<telerikDataGrid:RadDataGrid x:Name="dataGrid"
SelectionUnit="Cell" />
var dataGrid = new RadDataGrid();
dataGrid.SelectionUnit = Telerik.XamarinForms.DataGrid.DataGridSelectionUnit.Cell;
SelectionMode
The SelectionMode property (type of Telerik.XamarinForms.DataGrid.DataGridSelectionMode) provides the following modes:
- Single: Single unit may be selected(by default).
- Multiple: Multiple units may be selected.
- None: No selection is allowed.
The example below shows how to set SelectionMode in XAML and code-behind:
<telerikDataGrid:RadDataGrid x:Name="dataGrid"
SelectionMode="Multiple" />
var dataGrid = new RadDataGrid();
dataGrid.SelectionMode = Telerik.XamarinForms.DataGrid.DataGridSelectionMode.Multiple;
SelectedItems
Once you make a selection, you can get or modify the collection with the selected Items by using the SelectedItems property:
- SelectedItems property (type of ObservableCollection<object>): Gets or Modifies an ObservableCollection of the currently selected Items (their type depends on the applied SelectionUnit, that is, DataGridCellInfo for Cell and Data Item for Row).
You can listen to the CollectionChanged event of the SelectedItems directly.
Events
-
SelectionChanged: An event that is triggered whenever the SelectedItems collection is changed. The SelectionChanged event handler receives two parameters:
- The sender argument, which is of type object, but can be cast to the RadDataGrid type.
- A DataGridSelectionChangedEventArgs object, which provides the following properties:
- RemovedItems - gets a list of the removed items from the SelectedItems collection.
- AddedItems - gets a list of the added items to the SelectedItems collection.
Methods
Additional functionalities for programmatic selecting and deselecting items are exposed by RadDataGrid as methods. They also depend on the applied SelectionUnit.
Methods for programmatic selection when SelectionUnit is "Row":
- SelectItem(object item): Selects the specified data item and adds it in the SelectedItems collection.
- DeselectItem(object item): Removes the selection for the specified data item and removes it from the SelectedItems collection.
Methods for programmatic selection when SelectionUnit is "Cell":
- SelectCell(DataGridCellInfo item): Selects the grid cell as defined by the specified cell info.
- DeselectCell(DataGridCellInfo item): Removes the selection for the grid cell defined by the specified cell info.
Methods for programmatic selection of all items
- SelectAll(): Selects all the items as defined when SelectionMode is "Multiple".
- DeselectAll(): Clears the current selected items as defined by the SelectionUnit property.
Example
In order to illustrate how these methods can be used, let's have the following example:
1) Add a sample business object:
public class Person
{
public string Name { get; set; }
public int Age { get; set; }
public string Department { get; set; }
}
2) Add a ViewModel with a list of "Person" objects:
public class ViewModel
{
public ViewModel()
{
this.People = new ObservableCollection<Person>()
{
new Person { Name = "Kiko", Age = 23, Department = "Production" },
new Person { Name = "Jerry", Age = 23, Department = "Accounting and Finance"},
new Person { Name = "Ethan", Age = 51, Department = "Marketing" },
new Person { Name = "Isabella", Age = 25, Department = "Marketing" },
new Person { Name = "Joshua", Age = 45, Department = "Production" },
new Person { Name = "Logan", Age = 26, Department = "Production"},
new Person { Name = "Aaron", Age = 32, Department = "Production" },
new Person { Name = "Elena", Age = 37, Department = "Accounting and Finance"},
new Person { Name = "Ross", Age = 30, Department = "Marketing" },
};
}
public ObservableCollection<Person> People { get; set; }
}
3) Add the RadDataGrid definition:
<telerikDataGrid:RadDataGrid x:Name="dataGrid"
ItemsSource="{Binding People}" />
4) Set the ViewModel class as a BindingContext:
this.BindingContext = new ViewModel();
Now you use various approaches to select the first employee from the Marketing department. Each snippet shows a possible approach:
- In the case of Row selection, use SelectItem method:
var firstMarketingItem = ((ObservableCollection<Person>)this.dataGrid.ItemsSource).First(p => p.Department == "Marketing");
this.dataGrid.SelectItem(firstMarketingItem);
- For Cell selection, use SelectCell method - it takes as a parameter a DataGridCellInfo object. DataGridCellInfo object can be easily created using the needed data item (of type Person in our case) and setting the column corresponding to the cell you'd need to select.
var firstMarketingCell = ((ObservableCollection<Person>)this.dataGrid.ItemsSource).First(p => p.Department == "Marketing");
this.dataGrid.SelectCell(new DataGridCellInfo(firstMarketingCell, this.dataGrid.Columns[2]));
- Lastly, you call the SelectAll/DeselectAll method like this:
this.dataGrid.SelectAll();