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

The N+1 Select problem


The N + 1 Select problem arises due to an internal data store call made by any ORM framework to perform a single operation. The problem could be outlined as follows:

  1. A list of entities was returned that will be further iterated to perform some additional operation.
  2. Assuming a navigational property is accessed inside the iteration:
    • Each time an iteration tries to access the navigational property, a database hit occurs
    • The hits will happen N times for N number of items returned in the first step
  3. This makes the application perform N+1 Select (N for the iterations and 1 for the first call that retrieves the list), which should have been performed in a single database call.

This behavior is often termed as lazy loading in any ORM frameworks, which loads the subsequent/dependent data only when required. The lazy loading is yet to be supported by EF Core. This can be verified in the EF Core road map, which lists it as Stretch goals, as shown in the following screenshot:

The issue...