Blazor for Beginners code error in OnSelected

[Kenneth]

Is anyone using the code from the free book and getting it to build/run?

I can't get past the event call back code on pages 46-47. I find the code references OnSelected="HandleItemSelected" delegate when no procedure/var exists with that name. I think I need to add a delegate to WeatherDay component.

Book:

<WeatherDay TemperatureC="forecast.TemperatureC"
Summary="@forecast.Summary"
DayOfWeek="forecast.Date.DayOfWeek"
OnSelected="HandleItemSelected"
Selected="forecast.Selected">

I tried:

<WeatherDay TemperatureC="forecast.TemperatureC"
Summary="@forecast.Summary"
DayOfWeek="forecast.Date.DayOfWeek"
OnSelected="HandleOnSelected"
Selected="forecast.Selected">

[Marin Bratanov]

Hi Kenneth,

Thank you for reaching out. Indeed, it seems that a sample handler is missing from the book, and I will forward this issue to the people working on it.

Here's a sample handler that you can try in the WeeklyForecast.razor file (I am also attaching a runnable project that demonstrates it):

    async Task HandleItemSelected(DayOfWeek day)
    {
        WeatherForecast selectedForecast = forecasts.Where(f => f.Date.DayOfWeek == day).First();
        if(selectedForecast != null)
        {
            selectedForecast.Selected = !selectedForecast.Selected;
        }
    }

 

Regards,
Marin Bratanov
Progress Telerik

[DR]

Almost 2 years later, and the book has not yet been corrected?

Also other 'typos' like

above  Summary="@forecast.Summary" where the leading @ is not needed

page 25 "API endpionts for data"  (endpoints spelled wrong)

page 33 "where it should to be placed"

page 66 "diffing algorithm to to ensure"

[Hristian Stefanov]

Hi Dennis,

I've reached out to the author of the book. We are now waiting for a response. I will keep you updated.

Thank you for your patience while we investigate the matter here.

[Ed]

above  Summary="@forecast.Summary" where the leading @ is not needed

Addressing the typos, however the statement above is correct.

Because the parameter Summary is a String, if the `@` is omitted then the value becomes the string literal "forecast.Summary" and not the value of the property `forecast.Summary`.

[Ed]

Thanks for making me aware of these issues. There are currently plans to replace the ebook with a much larger and complete ebook from O'Riley for free to our customers and community 🥳

In the mean time Ill see if theres a way to quicky address the typos described here.

Best regards,

Ed Charbeneau

[DR]

Thanks Ed.  Hopefully you will use Visual Studio 2022 / .NET 6, and address the warnings, etc. ;)

(Also, for Theme Chooser demo, it's not clear about where light.css and dark.css come from and where to reference them.)

 

 

 

[Ed]

It was implied that there was a theoretical app with light and dark themes, no code for those .css files is shown in the e-book. However, you can easily create them using a tool like themebuilder.telerik.com or visit https://bootswatch.com/ (see Darkly & Flatly).

[Ed]

There's also a GitHub repo. I'm updating it for .NET 6 per your request. https://github.com/EdCharbeneau/BlazorBookExamples

[Ed]

The GitHub project is updated to .NET 6. I think the warnings you refer to are due to the new `Nullable` feature in C# 9? These warnings can get quite bothersome in Razor. I addressed them in the repo, but it will take time to get the edits into the book.