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)

Querying EF Core models

Now that we have a model that maps to the Northwind database and two of its tables, we can write some simple LINQ queries to fetch data. You will learn much more about writing LINQ queries in Chapter 12, Querying and Manipulating Data Using LINQ. For now, just write the code and view the results:

  1. Open Program.cs and import the following namespaces:
    using static System.Console; 
    using Packt.Shared;
    using Microsoft.EntityFrameworkCore; 
    using System.Linq;
  2. In Program, define a QueryingCategories method, and add statements to do these tasks, as shown in the following code:
    • Create an instance of the Northwind class that will manage the database. Database context instances are designed for short lifetimes in a unit of work. They should be disposed as soon as possible so we will wrap it in a using statement.
    • Create a query for all categories that include their related products.
    • Enumerate through the categories...