We can display the Popup window in Blazor using Radzen Controls like this
Step 1: Configure the project setup like this https://chandradev819.wordpress.com/2022/09/28/getting-started-with-radzen-blazor-controls/
Step 2: Register the Dialogs service like this

Step 3: Include <RadzenDialog/> component as global in Shared\MainLayout.razor

Step 4: Create any Razor component and write the code for simple popup window like this
@page "/popup"
@inject DialogService DialogService
<RadzenButton ButtonType="ButtonType.Submit" Text="Test Popup" TextTransform="None"
Click=@(args => DialogService.Confirm("Confirm Action?", "Test Popup", new ConfirmOptions() { OkButtonText = "Yes", CancelButtonText = "No" })) />

Now we will create cascading popup window
@page "/SimplePopup"
@inject DialogService DialogService
<RadzenButton Text="Show dialog with inline Blazor content" Click=@ShowInlineDialog />
@code {
async Task ShowInlineDialog()
{
var result = await DialogService.OpenAsync("Login Popup", ds =>
@<div>
<div class="row">
<fieldset class="border p-2">
<legend class="w-auto">
<div class="col-md-6">
<RadzenButton Text="Login as User" Click="() => LoginAsUser()"
Style="margin-bottom: 10px; width: 250px" />
<RadzenButton Text="Login as Guest" Click="() => LoginAsGuest()"
Style="margin-bottom: 10px; width: 250px" />
<RadzenButton Text="Login as Admin" Click="() => LoginAsAdmin()"
Style="margin-bottom: 10px; width: 250px" />
</div>
</legend>
</fieldset>
</div>
</div>
);
Console.WriteLine($"Dialog result: {result}");
}
async Task ShowInlineDialog1()
{
var result = await DialogService.OpenAsync("Login Popup", ds =>
@<div>
<div class="row">
<fieldset class="border p-2">
<legend class="w-auto">
<div class="col-md-12">
<p>Testing</p>
</div>
</legend>
</fieldset>
</div>
</div>
);
Console.WriteLine($"Dialog result: {result}");
}
private void LoginAsUser()
{
ShowInlineDialog1();
}
private void LoginAsGuest()
{
}
private void LoginAsAdmin()
{
}
}

Summary: In above post we saw that it is very straight forward to create model popup in Blazor using Radzen Controls.
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