Book Image

C# 9 and .NET 5 – Modern Cross-Platform Development - Fifth Edition

By : Mark J. Price
Book Image

C# 9 and .NET 5 – Modern Cross-Platform Development - Fifth Edition

By: Mark J. Price

Overview of this book

In C# 9 and .NET 5 – Modern Cross-Platform Development, Fifth Edition, expert teacher Mark J. Price gives you everything you need to start programming C# applications. This latest edition uses the popular Visual Studio Code editor to work across all major operating systems. It is fully updated and expanded with a new chapter on the Microsoft Blazor framework. The book’s first part teaches the fundamentals of C#, including object-oriented programming and new C# 9 features such as top-level programs, target-typed new object instantiation, and immutable types using the record keyword. Part 2 covers the .NET APIs, for performing tasks like managing and querying data, monitoring and improving performance, and working with the file system, async streams, serialization, and encryption. Part 3 provides examples of cross-platform apps you can build and deploy, such as websites and services using ASP.NET Core or mobile apps using Xamarin.Forms. The best type of application for learning the C# language constructs and many of the .NET libraries is one that does not distract with unnecessary application code. For that reason, the C# and .NET topics covered in Chapters 1 to 13 feature console applications. In Chapters 14 to 20, having mastered the basics of the language and libraries, you will build practical applications using ASP.NET Core, Model-View-Controller (MVC), and Blazor. By the end of the book, you will have acquired the understanding and skills you need to use C# 9 and .NET 5 to create websites, services, and mobile apps.
Table of Contents (23 chapters)

Loading patterns with EF Core

There are three loading patterns that are commonly used with EF: eager loading, lazy loading, and explicit loading. In this section, we're going to introduce each of them.

Eager loading entities

In the QueryingCategories method, the code currently uses the Categories property to loop through each category, outputting the category name and the number of products in that category. This works because when we wrote the query, we used the Include method to use eager loading (also known as early loading) for the related products:

  1. Modify the query to comment out the Include method call, as shown in the following code:
    IQueryable<Category> cats = 
      db.Categories; //.Include(c => c.Products);
  2. In Main, comment all methods except QueryingCategories.
  3. Run the console application and view the result, as shown in the following partial output:
    Beverages has 0 products. 
    Condiments has 0 products. ...