Creating a popup in Blazor using C# method

Question

I have a simple page index.razor with a button:

<a class="btn btn-login" @onclick="RedirectPage" >Log in</a>

<div
    @bind-Visible="@InvalidLogin"
    BodyText="Error">
</div>

@code{
    InvalidLogin {get; set;} = false;
}

Where the function RedirectPage checks if values are valid. If they are not, I want a popup giving information:

private void RedirectPage
{
    this.InvalidLogin = true;
}

This function is in the index.razor.cs and has been added with @using in the correct namespace.

How can I create it so that a popup shows up whenever the button is clicked?

Answer 1

You can create a simple popup (or modal dialog) component. Below, I wrote a sample popup razor component using Bootstrap 5 toast component.

Popup.razor file

@{
    var showClass = IsVisible ? "d-block" : "d-none";
}

<div class="toast-container p-3 @showClass" data-bs-autohide="true" data-bs-delay="5000">
    <div class="toast show" role="alert" aria-live="assertive" aria-atomic="true">
        <div class="toast-header">
            <strong class="me-auto">@HeaderText</strong>
            <button type="button" class="btn-close" aria-label="Close" @onclick="Close"></button>
        </div>

        <div class="toast-body">
            @BodyText
        </div>
    </div>
</div>

@code {
    [Parameter]
    public bool IsVisible { get; set; }

    [Parameter]
    public EventCallback<bool> IsVisibleChanged { get; set; }

    [Parameter]
    public string? HeaderText { get; set; }

    [Parameter]
    public string? BodyText { get; set; }

    public void Show(string bodyText, string headerText = "")
    {
        HeaderText = headerText;
        BodyText = bodyText;
        IsVisible = true;
        StateHasChanged();
    }

    private void Close()
    {
        HeaderText = string.Empty;
        BodyText = string.Empty;
        IsVisible = false;
        StateHasChanged();
    }
}

Using the Popup razor component in your code:

<a class="btn btn-login" @onclick="RedirectPage" >Log in</a>

<Popup @ref="popupRef" />

@code{
    private Popup popupRef;
    
    private void RedirectPage()
    {
        // Shows the popup at the center of the screen
        popupRef.Show("Popup body text");
    }
}