Configuring One-to-One Relationships

Overview

In this lesson, we’ll look at the conventions between two entities that result in a one-to-one relationship between their corresponding tables in the database. We’ll also look at how to supplement these conventions using data annotations and the fluent API.

One-to-one relationships require a reference navigation property at both ends. A unique index is also introduced on the foreign key property to ensure only one dependent entity links to the principal entity.

Note: The commands in this lesson generate code and files. Through the terminal, we can navigate to these files by using relevant Linux commands such as ls to view a list of files and directories, cd to change directories, and cat to view file contents. A SPA widget showing the updated project with the generated files is also available. Also, note that EF Core uses a timestamp within the generated file names. We represent these names with xxx.

Default conventions

By convention, EF Core identifies the dependent entity as the entity having a foreign key property. EF Core picks EmployeeId as the foreign key in this project because it matches the <navigation property name><principal key property name> pattern. Therefore, the one-to-one relationship is configured by default.

We’ll demonstrate configuring a ...