Blazor Grid Row Selection
The Ignite UI for Blazor Row Selection feature in Blazor Grid allows users to interactively select, highlight, or deselect a single or multiple rows of data. There are several selection modes available in the IgbGrid
:
- None Selection
- Multiple Selection
- Single Selection
Blazor Row Selection Example
The sample below demonstrates the three types of IgbGrid
's row selection behavior. Use the drop-down below to enable each of the available selection modes. Use the checkbox to hide or show the row selector checkboxes.
Setup
In order to setup row selection in the IgbGrid
, you just need to set the RowSelection
property. This property accepts GridSelectionMode
enumeration.
GridSelectionMode
exposes the following modes:
- None
- Single
- Multiple
Below we will take a look at each of them in more detail.
None Selection
In the IgbGrid
by default row selection is disabled (RowSelection
is None). So you can not select or deselect a row through interaction with the IgbGrid
UI, the only way to complete these actions is to use the provided API methods.
Single Selection
Single row selection can now be easily set up, the only thing you need to do, is to set RowSelection
to Single
property. This gives you the opportunity to select only one row within a grid. You can select a row by clicking on a cell or pressing the space key when you focus on a cell of the row, and of course you can select a row by clicking on the row selector field. When row is selected or deselected RowSelectionChanging
event is emitted.
<IgbGrid Width="100%"
Id="grid"
Height="100%"
RowSelection=GridSelectionMode.Single
PrimaryKey="Key"
@ref=Grid
AutoGenerate=true
RowSelectionChanging='RowSelectionChanging'
Data=northwindEmployees>
</IgbGrid>
@code {
private void RowSelectionChanging(IgbRowSelectionEventArgs args)
{
// handler for selection change
}
}
Multiple Selection
To enable multiple row selection in the IgbGrid
just set the RowSelection
property to Multiple
. This will enable a row selector field on each row and in the IgbGrid
header. The row selector allows users to select multiple rows, with the selection persisting through scrolling, paging, and data operations, such as sorting and filtering. The row also can be selected by clicking on a cell or by pressing the space key when a cell is focused. If you have selected one row and click on another while holding the shift key, this will select the whole range of rows. In this selection mode, when you click on a single row, the previous selected rows will be deselected. If you click while holding the ctrl key, the row will be toggled and the previous selection will be preserved.
<IgbGrid Width="100%"
Id="grid"
Height="100%"
RowSelection=GridSelectionMode.Multiple
PrimaryKey="Key"
@ref=Grid
AutoGenerate=true
Data=northwindEmployees>
</IgbGrid>
Notes
- Row selection will trigger
RowSelectionChanging
event. This event gives you information about the new selection, old selection, the rows that have been added and removed from the old selection. Also the event is cancellable, so this allows you to prevent selection. - When row selection is enabled row selectors are displayed, but if you don't want to show them, you can set
HideRowSelectors
to true. - When you switch between row selection modes at runtime, this will clear the previous row selection state.
API usage
Select Rows Programmatically
The code snippet below can be used to select one or multiple rows simultaneously (via PrimaryKey
). Additionally, the second parameter of this method is a boolean property through which you may choose whether the previous row selection will be cleared or not. The previous selection is preserved by default.
<IgbGrid Width="100%"
Id="grid"
Height="100%"
RowSelection=GridSelectionMode.Multiple
PrimaryKey="Key"
@ref=grid
AutoGenerate=true
Data=northwindEmployees>
</IgbGrid>
<IgbButton @onclick=Select>Select</IgbButton>
@code {
public IgbGrid grid;
private async void Select()
{
object[] array = new object[] { 1,2, 5 };
await this.grid.SelectRowsAsync(array, true);
}
}
This will add the rows which correspond to the data entries with IDs 1, 2 and 5 to the IgbGrid
selection.
Deselect Rows
If you need to deselect rows programmatically, you can use the DeselectRows
method.
<IgbGrid Width="100%"
Id="grid"
Height="100%"
RowSelection=GridSelectionMode.Multiple
PrimaryKey="Key"
@ref=grid
AutoGenerate=true
Data=northwindEmployees>
</IgbGrid>
<IgbButton @onclick=Deselect>Deselect</IgbButton>
@code {
public IgbGrid grid;
private async void Deselect()
{
object[] array = new object[] { 1, 2, 5 };
await this.grid.DeselectRowsAsync(array);
}
}
Row Selection Event
When there is some change in the row selection RowSelectionChanging
event is emitted. RowSelectionChanging
exposes the following arguments:
OldSelection
- array of row IDs that contains the previous state of the row selection.NewSelection
- array of row IDs that match the new state of the row selection.Added
- array of row IDs that are currently added to the selection.Removed
- array of row IDs that are currently removed according old selection state.Event
- the original event that triggered row selection change.Cancel
- allows you the prevent the row selection change.
<IgbGrid Width="100%"
Id="grid"
Height="100%"
RowSelection=GridSelectionMode.Multiple
PrimaryKey="Key"
@ref=Grid
AutoGenerate=true
RowSelectionChanging='RowSelectionChanging'
Data=northwindEmployees>
</IgbGrid>
@code {
private void RowSelectionChanging(IgbRowSelectionEventArgs args)
{
// handler
}
}
Select All Rows
Another useful API method that IgbGrid
provides is SelectAllRows
. By default this method will select all data rows, but if filtering is applied, it will select only the rows that match the filter criteria. If you call the method with false parameter, SelectAllRows(false)
will always select all data in the grid, even if filtering is applied.
Note Keep in mind that
SelectAllRows
will not select the rows that are deleted.
Deselect All Rows
IgbGrid
provides a DeselectAllRows
method, which by default will deselect all data rows, but if filtering is applied will deselect only the rows that match the filter criteria. If you call the method with false parameter, DeselectAllRows(false)
will always clear all row selection state even if filtering is applied.
How to get Selected Rows
If you need to see which rows are currently selected, you can get their row IDs with the SelectedRows
getter.
<IgbGrid Width="100%"
Id="grid"
Height="100%"
RowSelection=GridSelectionMode.Multiple
PrimaryKey="Key"
@ref=grid
AutoGenerate=true
Data=northwindEmployees>
</IgbGrid>
<IgbButton @onclick=GetSelected>Get selected</IgbButton>
@code {
public IgbGrid grid;
private async void GetSelected()
{
var selected = this.grid.SelectedRows;
}
}
Additionally, assigning row IDs to SelectedRows
will allow you to change the grid's selection state.
<IgbGrid Width="100%"
Id="grid"
Height="100%"
RowSelection=GridSelectionMode.Multiple
PrimaryKey="Key"
SelectedRows=selectedRows
@ref=Grid
AutoGenerate=true
Data=northwindEmployees>
</IgbGrid>
@code {
public object[] selectedRows = new object[] { 1, 2, 5 };
}
Row Selector Templates
You can template header and row selectors in the IgbGrid
and also access their contexts which provide useful functionality for different scenarios.
By default, the IgbGrid
handles all row selection interactions on the row selector's parent container or on the row itself, leaving just the state visualization for the template. Overriding the base functionality should generally be done using the RowSelectionChanging event. In case you implement a custom template with a Click
handler which overrides the base functionality, you should stop the event's propagation to preserve the correct row state.
Row Template
To create a custom row selector template, within the IgbGrid
you can use the RowSelectorTemplate
property. From the template you can access the implicitly provided context variable, with properties that give you information about the row's state.
The selected
property shows whether the current row is selected or not while the index
property can be used to access the row index.
igRegisterScript("WebGridRowSelectorTemplate", (ctx) => {
var html = window.igTemplating.html;
if (ctx.implicit.selected) {
return html`<div style="justify-content: space-evenly;display: flex;width: 70px;">
<span> ${ctx.implicit.index}</span>
<igc-checkbox checked></igc-checkbox>
</div>`;
} else {
return html`<div style="justify-content: space-evenly;display: flex;width: 70px;">
<span> ${ctx.implicit.index}</span>
<igc-checkbox></igc-checkbox>
</div>`;
}
}, false);
The rowID
property can be used to get a reference of an IgbGrid
row. This is useful when you implement a click
handler on the row selector element.
In the above example we are using an IgbCheckbox
and we bind rowContext.selected
to its checked
property. See this in action in our Row Numbering Demo.
Header Template
To create a custom header selector template, within the IgbGrid
, you can use the HeadSelectorTemplate
property. From the template you can access the implicitly provided context variable, with properties that give you information about the header's state.
The SelectedCount
property shows you how many rows are currently selected while totalCount
shows you how many rows there are in the IgbGrid
in total.
public RenderFragment<IgbHeadSelectorTemplateContext> Template = (context) =>
{
return @<div> <img style="min-width:80px;" src="https://www.infragistics.com/angular-demos-lob/assets/images/card/avatars/igLogo.png"/></div>;
};
The SelectedCount
and TotalCount
properties can be used to determine if the head selector should be checked or indeterminate (partially selected).
Row Numbering Demo
This demo shows the usage of custom header and row selectors. The latter uses Index
to display row numbers and an IgbCheckbox
bound to Selected
.
Excel Style Row Selectors Demo
This demo uses custom templates to resemble Excel-like header and row selectors.
Conditional Selection Demo
This demo prevents some rows from being selected using the RowSelectionChanging
event and a custom template with disabled checkbox for non-selectable rows.
API References
IgbGrid
IgbGridRow
Cell
Additional Resources
- Selection
- Cell selection
- Paging
- Filtering
- Sorting
- Summaries
- Column Moving
- Column Pinning
- Column Resizing
- Virtualization and Performance
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