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  • Book Overview & Buying Entity Framework Core Cookbook
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Entity Framework Core Cookbook

Entity Framework Core Cookbook - Second Edition

By : Ricardo Peres
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Entity Framework Core Cookbook

Entity Framework Core Cookbook

2 (3)
By: Ricardo Peres

Overview of this book

Entity Framework is a highly recommended Object Relation Mapping tool used to build complex systems. In order to survive in this growing market, the knowledge of a framework that helps provide easy access to databases, that is, Entity Framework has become a necessity. This book will provide .NET developers with this knowledge and guide them through working efficiently with data using Entity Framework Core. You will start off by learning how to efficiently use Entity Framework in practical situations. You will gain a deep understanding of mapping properties and find out how to handle validation in Entity Framework. The book will then explain how to work with transactions and stored procedures along with improving Entity Framework using query libraries. Moving on, you will learn to improve complex query scenarios and implement transaction and concurrency control. You will then be taught to improve and develop Entity Framework in complex business scenarios. With the concluding chapter on performance and scalability, this book will get you ready to use Entity Framework proficiently.
Table of Contents (10 chapters)
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9
Index

Composite primary keys

When we have composite primary keys, we need to give them an order.

Problem

In some cases, you may need to have composite primary keys, that is, have a primary key that is composed of not a single column, but many. This is certainly a valid requirement, but, unless you configure it properly, Entity Framework will not work. And something that does not work is mapping attributes:

using System;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
public class MyClassWithCompositeKey
{
[Key]
  [Column(Order = 0)]
  public int KeyA { get; set; }
[Key]
  [Column(Order = 1)]
public string KeyB { get; set; }
  [Key]
  [Column(Order = 2)]
public Guid KeyC { get; set; }
}

Again, the preceding code will not work; it will be totally ignored by Entity Framework.

How to solve it…

You need to mark all of your properties that make up the primary key with an order number; each will have its own, and you need to use fluent mapping for this...

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Entity Framework Core Cookbook
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