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Alert

in namespace DotVVM.Bootstrap5.Controls

Displays contextual feedback messages for users.

Usage & Scenarios

Displays contextual alert messages for users.

https://getbootstrap.com/docs/5.2/components/alerts/

Sample 1: Basic Alert

The Alert control has the Type property which you can use to set the color of the alert message.

page.dothtml
ViewModel.cs

<bs:Alert Type="Success">
  Alert: type Success
</bs:Alert>

<bs:Alert Type="Danger">
  Alert: type Danger
</bs:Alert>

<bs:Alert Type="Info">
  Alert: type Info
</bs:Alert>

<bs:Alert Type="Warning">
  Alert: type Warning
</bs:Alert>

<bs:Alert Type="{value: Type}" Text="Bindable type"/>

public class ViewModel : DotvvmViewModelBase
{
    public AlertType Type { get; set; } = AlertType.Dark;
}

Sample 2: Dismissible Alert

If you want to allow the user to hide the alert, use the IsDismissible property. When IsDismissible property is set to true, a close button will be rendered.

The IsDismissed property gets or sets if the alert is dismissed. You can use data-binding on it to determine whether the user has dismissed the alert or not.

The Dismissed event is called after the alert is dismissed.

page.dothtml
ViewModel.cs

<bs:Alert IsDismissible="true">
  Dismissable alert
</bs:Alert>

<bs:Alert IsDismissed="{value: Dismissed}" 
          IsDismissible="true"
          Dismissed="{command: AlertDismissed()}" 
          Text="Click the button" />

<dot:Button Text="Show/Hide" Click="{command: Dismiss()}"/>
<p>
    Dismissed: {{value: Dismissed}}
</p>
<p>{{value: Text}}</p>

public class ViewModel : DotvvmViewModelBase
{
    public bool Dismissed { get; set; } = false;

    public string Text { get; set; }

    public void AlertDismissed()
    {
        Text = "The alert was dismissed.";
    }

    public void Dismiss()
    {
        Dismissed = !Dismissed;
    }
}

Sample 3: Common Usage

The typical use of the Alert control is to have two properties in the viewmodel (AlertText and AlertType) which are bound to the properties of the Alert control.

Notice that the properties are marked with the Bind attribute setting the direction to ServerToClient. That's because we don't need to send the property values to the server when we are making a postback. We only need to send the new value to the client if the properties are changed.

We suggest to put the AlertText and AlertType properties into the viewmodel of the master page and create a method which does some kind of exception handling. Then, you can use it on all places, in your application.

@viewModel Dotvvm.Samples.Alert.sample3.ViewModel, Dotvvm.Samples

<!-- the alert is somewhere in master page -->
<bs:Alert Text="{value: AlertText}" Type="{value: AlertType}" />

<!-- content page -->
<bs:Button Text="Do Something" Click="{command: DoSomething()}"/>

public class ViewModel : MyViewModelBase
{
    
    public void DoSomething()
    {
        ExecuteWithAlert(() =>
        {
            // the action
        });
    }
}

public class MyViewModelBase : DotvvmViewModelBase
{

    [Bind(Direction.ServerToClient)]
    public string AlertText { get; set; }

    [Bind(Direction.ServerToClient)]
    public AlertType AlertType { get; set; }


    /// <summary>
    /// Executes the specified action and sets the appropriate alert messages.
    /// </summary>
    protected void ExecuteWithAlert(Action actionToExecute, 
        string successText = "The operation was successful.", 
        string errorText = "Sorry, an unexpected error has occurred.")
    {
        try
        {
            // execute the action
            actionToExecute();

            AlertText = successText;
            AlertType = AlertType.Success;
        }
        catch (DotVVM.Framework.Hosting.DotvvmInterruptRequestExecutionException)
        {
            // this exception is used for redirecting - don't catch it
            throw;
        }
        catch (Exception)
        {
            AlertText = errorText;
            AlertType = AlertType.Danger;
        }
    }

}

Sample 4: Text and Header Text

Alert containes two options for text. First option is property Text and the second is propery HeaderText. Both property are not required, but if users set both to null or empty string, than, by default, is alert hidden. User can override this behaviou by setting property Visible.

page.dothtml
ViewModel.cs

<bs:Alert Type="Success" Text="{value: AdvancedText}" HeaderText="{value: AdvancedHeader}" />

<dot:button Click="{command: AdvancedHeader = null}">Set Header to null </dot:button>
<dot:button Click="{command: AdvancedHeader = "Changed Advanced Header"}">Set Header to text </dot:button>
<dot:button Click="{command: AdvancedText = null}">Set Text to null </dot:button>
<dot:button Click="{command: AdvancedText = "Changed Advanced Text"}">Set Text to text </dot:button>

public class ViewModel : DotvvmViewModelBase
{
    public string? AdvancedHeader { get; set; } = "Advanced Header";
    public string? AdvancedText { get; set; } = "Advanced Text";
}

Show all inherited properties

Properties

Name	Type	Description	Notes	Default Value
ClientIDMode	ClientIDMode	Gets or sets the client ID generation algorithm.	attribute inner element static value bindable default	Static
Content	List<DotvvmControl>	Gets or sets the content placed inside the control.	attribute inner element static value bindable default	null
DataContext	Object	Gets or sets a data context for the control and its children. All value and command bindings are evaluated in context of this value. The DataContext is null in client-side templates.	attribute inner element static value bindable default	null
HeaderContent	List<DotvvmControl>	Gets or sets a custom template for the alert header.	attribute inner element static value bindable default	null
HeaderText	String	Gets or sets a plain text for the alert header.	attribute inner element static value bindable default	null
ID	String	Gets or sets the control client ID within its naming container.	attribute inner element static value bindable default	null
IncludeInPage	Boolean	Gets or sets whether the control is included in the DOM of the page.	attribute inner element static value bindable default	True
IsDismissed	IValueBinding<Boolean>	Gets or sets a boolean binding whether the alert has been dismissed.	attribute inner element static value bindable default	null
IsDismissible	Boolean	Gets or sets whether a close icon should be displayed in the top right corner of the alert.	attribute inner element static value bindable default	False
Text	String	Gets or sets the text inside the control.	attribute inner element static value bindable default	null
Type	AlertType	Gets or sets the type of the alert. Possible values are Primary, Secondary, Success, Danger, Warning, Info, Light and Dark.	attribute inner element static value bindable default	Primary
Visible	Boolean	Gets or sets whether the control is visible. When set to false, `style="display: none"` will be added to this control.	attribute inner element static value bindable default	True

Events

	Name	Type	Description
	Dismissed	ICommandBinding	Gets or sets the command that will be triggered when the alert is dismissed.