Predefined Dialogs - Alert, Confirm, Prompt

Telerik UI for Blazor provides styled substitutes to the standard confirm, alert and prompt dialogs. They match the Theme of the components to make it obvious to the user that the modal dialog is coming from your application.

To use these dialogs, receive a cascading parameter of type Telerik.Blazor.DialogFactory. It exposes the methods you can use in your method calls.

[CascadingParameter]
public DialogFactory Dialogs { get; set; }

The predefined dialogs can only be used inside child Razor components of the TelerikRootComponent. This is easily achieved in standard Blazor apps where the TelerikRootComponent resides inside the layout file. When using UI for Blazor in ASP.NET apps, an additional child component is needed.

There are three available ready-made dialogs:

• Alert
• Confirm
• Prompt

Alert

The alert dialog usually shows the user that something went wrong, such as a major error that requires their attention and blocks the UI, as opposed to a notification that is not modal and is small.

Use an Alert dialog

@* Use Alert dialogs, monitor the console for when the code continues *@

<TelerikButton OnClick="@ShowAlert">Show Alert</TelerikButton>
<TelerikButton OnClick="@ShowAlertWithTitle">Show Alert with Custom Title</TelerikButton>
<TelerikButton OnClick="@ShowAlertWithTitleAndButton">Show Alert with Custom Title and Custom Button</TelerikButton>

@code {
    [CascadingParameter]
    private DialogFactory Dialogs { get; set; }

    private async Task ShowAlert()
    {
        await Dialogs.AlertAsync("Something went wrong!");

        Console.WriteLine("The user dismissed the alert box.");
    }

    private async Task ShowAlertWithTitle()
    {
        await Dialogs.AlertAsync("Something went wrong!", "Read this!");

        Console.WriteLine("The user dismissed the alert box with the custom title.");
    }

    private async Task ShowAlertWithTitleAndButton()
    {
        await Dialogs.AlertAsync("Something went wrong!", "Read this!", "DONE");

        Console.WriteLine("The user dismissed the alert box with the custom title and custom button.");
    }
}

Confirm

The confirm dialog returns a bool value that indicates which button the user clicked - true for the OK button and false for the Cancel button. This lets you await its execution, and then continue the application logic based on that decision. The method that calls it must be async Task and not async void in order to await the execution.

Use a Confirm dialog

@* Use Confirm dialogs, monitor the console for when and how the code continues *@

<TelerikButton OnClick="@ShowConfirm">Show Confirm</TelerikButton>
<TelerikButton OnClick="@ShowConfirmWithTitle">Show Confirm with Custom Title</TelerikButton>
<TelerikButton OnClick="@ShowConfirmWithTitleAndButtons">Show Confirm with Custom Title and Custom Buttons</TelerikButton>

@code {
    [CascadingParameter]
    private DialogFactory Dialogs { get; set; }

    private async Task ShowConfirm()
    {
        bool isConfirmed = await Dialogs.ConfirmAsync("Are you sure?");

        if (isConfirmed)
        {
            Console.WriteLine("The user is sure, continue.");
        }
        else
        {
            Console.WriteLine("The user changed their mind");
        }
    }

    private async Task ShowConfirmWithTitle()
    {
        bool isConfirmed = await Dialogs.ConfirmAsync("Are you sure?", "Confirmation!");

        Console.WriteLine($"The user is sure: {isConfirmed}.");
    }

    private async Task ShowConfirmWithTitleAndButtons()
    {
        bool isConfirmed = await Dialogs.ConfirmAsync("Are you sure?", "Confirmation!", "YES, I'm sure", "NO, I'm not sure");

        Console.WriteLine($"The user is sure: {isConfirmed}.");
    }
}

Prompt

The prompt dialog returns a string that the user enters when they press OK, and null when they press Cancel. This lets you await its execution, and then continue the application logic based on that decision. The method that calls it must be async Task and not async void in order to await the execution.

Use a Prompt dialog

@* Use Prompt dialogs, monitor the console for when and how the code continues *@

<TelerikButton OnClick="@ShowPrompt">Show Prompt</TelerikButton>
<TelerikButton OnClick="@ShowPromptWithTitle">Show Prompt with Custom Title</TelerikButton>
<TelerikButton OnClick="@ShowPromptWithTitleAndDefaultText">Show Prompt with Title and Default Input Text</TelerikButton>
<TelerikButton OnClick="@ShowPromptWithTitleDefaultTextAndButtons">Show Prompt with Title, Default Input Text and Custom Buttons</TelerikButton>

@code {
    [CascadingParameter]
    private DialogFactory Dialogs { get; set; }

    private async Task ShowPrompt()
    {
        string userInput = await Dialogs.PromptAsync("Enter your answer.");

        if (userInput == null)
        {
            Console.WriteLine("The user will not answer.");
        }
        else
        {
            Console.WriteLine($"The user said: {userInput}");
        }
    }

    private async Task ShowPromptWithTitle()
    {
        string userInput = await Dialogs.PromptAsync("Enter answer:", "Input needed");

        Console.WriteLine($"The user answer: {userInput}");
    }

    private async Task ShowPromptWithTitleAndDefaultText()
    {
        string userInput = await Dialogs.PromptAsync("Enter answer:", "Input needed", "Default Text");

        Console.WriteLine($"The user answer: {userInput}");
    }

    private async Task ShowPromptWithTitleDefaultTextAndButtons()
    {
        string userInput = await Dialogs.PromptAsync("Enter answer:", "Input needed", "Default Text", "READY", "REJECT");

        Console.WriteLine($"The user answer: {userInput}");
    }
}

See Also

• Live Demo: Predefined Dialogs