Adding a spinner to a Blazor application


My first project with Blazor was building a testing application for a test of APIs.  This was low risk while changeling enough to make it fun.  The application started simple, just submit a form of data to the API.  Seems simple enough.

I created the form, used a service to talk to the API and got it up and running fairly quick.  It was at this point that I realized the API was a long running process as far as the user is concerned.  Being the good developer, I decided to add a “spinner” to the UI to let the user know it was working.  This is when the fun started.

For the actual spinner, I just did a google search for a cool looking spinner.  The hardest part of that was choosing which one to use.

<div class="spinner @cursorCSS"></div>

I then wired it in to the Blazor Page:

    protected void Submit()
    {
        //Show Sending...
        cursorCSS = "";
        this.StateHasChanged();
        response = Service.Post(userModel);
        if (response.Errors.Any())
        {
            errorCss = "errorOn";
        }
        //turn sending off
        cursorCSS = "cursorSpinOff";
        this.StateHasChanged();
    }

Ran my test and the spinner did not show ☹ .  Through some debugging I noticed that if I removed the cursorSpinOff line of code the spinner would show but after the Service Post ran.

After some time on Stack OverFlow and a thanks to Dani Herrera, I found out I was trying to refresh the UI thread with the this.StateHasChnaged, but I was on the UI thread.
So, I changed the method to be async and cleaned up the code around the spinner:

    protected async Task Submit()
    {
         spinning=true;
         response = Service.Post(userModel);
         if (response.Errors.Any())
        {
           errorCss = "errorOn";
        }
        spinning=false;
        await Task.CompletedTask; // just to avoid non await warning.
    }

For the spinner:
  @if (spinning)
  {
      <div class="spinner"></div>
  }

Now the button clicks calls the Submit Method on the UI thread, that spawns off the service post to its own thread, the UI thread continues, and page is refresh showing the Spinner.
Once the service post is done, the spinner variable is set to false the page is updated tuning off the spinner.

Now the user has some feedback on when we are calling the server side post.



Comments

Post a Comment

Popular posts from this blog

Yes, Blazor Server can scale!

Image
From the very beginning of the release of Blazor Server naysayers have incorrectly stated that Blazor Server can not scale.  They usually state that the limit is 5,000 concurrent users. There are several misconceptions and wrong assumptions about their statement.  Let's break it down and get a better understanding of Blazor server-side scaling. What is the "limit" for users When Microsoft talks about the need to scale an application, what they are saying is that when a normal response for any concurrent user is taking longer than 200 ms, the system is not performant and needs to scale. We will accept that definition: If any normal user response is taking longer than 200 ms, the system needs to scale for concurrent users. By a normal response, we are referring to a page get, a post, etc.  Large database access requests would not be included in this measurement. What is scaling There are 2 common ways to scale, scale, out horizontally, and scale-up, up vertically. In our di...
Read more

Blazor - Cool Blur Loading Page

Image
  I was working on a project and wanted an original way of showing the user the application was loading besides using the normal "Loading...." text.  I came across a website page and thought I could refactor that into what I was looking for. When my application starts, it displays a full-screen image with a count down while the page loads.  As a special effect, I want to unblur the image the closer it gets to the applicaiton finishing loading.  Once the teh count down is done, we pause for 1 sec, for effect, then proceed to the application.  I think it turned out pretty cool.  See the demo here . I used the server side Blazor project template in my example, but the code should work on any Blazor template. Template changes 1. Rename the original Index.razor page to "home".  Besure to change the routing at the top of the page as well.      @page "/home" 2. Create a new Index.razor page     a. Add routing      ...
Read more

Blazor new and improved Search Box

 Back in March, I posted a new Blazor data grid with a search box ( see post ).  Since then I have found a new and improved search box that I wanted to implement.  The search part is implemented the same.  What I added was the ability for the user to narrow down the search by selecting which field they wanted to search on.  This will help the user find what they are looking for and in a large collection, the search will end up being faster. The goal of making the change was to make the search box a new component and have it handle the UI functionality part. Prep Work Here is the prep work I did before adding the search box: Started with the source code from the post listed above. Upgraded the project to .Net 5 Upgraded the Nuget packages that were out of date. Ensured every build and run. Change to a Component I wanted to create a component for the search box so I could use it in other applications.   1. Create a Folder under UIControls called "SearchB...
Read more