Book Image

Mastering Entity Framework Core 2.0

By : Prabhakaran Anbazhagan
Book Image

Mastering Entity Framework Core 2.0

By: Prabhakaran Anbazhagan

Overview of this book

Being able to create and maintain data-oriented applications has become crucial in modern programming. This is why Microsoft came up with Entity Framework so architects can optimize storage requirements while also writing efficient and maintainable application code. This book is a comprehensive guide that will show how to utilize the power of the Entity Framework to build efficient .NET Core applications. It not only teaches all the fundamentals of Entity Framework Core but also demonstrates how to use it practically so you can implement it in your software development. The book is divided into three modules. The first module focuses on building entities and relationships. Here you will also learn about different mapping techniques, which will help you choose the one best suited to your application design. Once you have understood the fundamentals of the Entity Framework, you will move on to learn about validation and querying in the second module. It will also teach you how to execute raw SQL queries and extend the Entity Framework to leverage Query Objects using the Query Object Pattern. The final module of the book focuses on performance optimization and managing the security of your application. You will learn to implement failsafe mechanisms using concurrency tokens. The book also explores row-level security and multitenant databases in detail. By the end of the book, you will be proficient in implementing Entity Framework on your .NET Core applications.
Table of Contents (20 chapters)
Title Page
Credits
About the Author
About the Reviewers
www.PacktPub.com
Customer Feedback
Dedication
Preface
4
Building Relationships – Understanding Mapping

Fluent API


We already had a sneak peek into the Fluent API, without which the relationship can never be complete (in a few cases, it is mandatory). 

Identifying navigation property and inverse navigation

We used the Fluent API in one-to-one and many-to-many relationships. We will use the same method to leverage the terminologies we have seen so farThe HasOne and HasMany methods allow us to identify the navigation property in the dependent entity or simply a reference navigation property.

The following code configures the foreign key explicitly in the one-to-many relationship:

        modelBuilder.Entity<TagPost>()
          .ToTable("TagPost")
          .HasOne(x => x.Tag)
          .WithMany(x => x.TagPosts)
          .HasForeignKey(x => x.TagId);

The following diagram, the TagId highlighted is required for the foreign key of the relationship:

The HasOne method identifies the Tag navigation in the TagPost entity. The WithOne and WithMany methods allow us to identify the inverse...