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Move Entity Framework Core v5.0 to a Separate Project

It is a fundamental architectural principle for a commercial web application to not have data access functionality mixed in the same layer and logic that controls the display.

As usual, Microsofts tutorials just mix them in together, something no professional developer would ever do. Core 5 is fairly new and the only other tutorial I could find was all controlled from the CLI (surely 99% of us would just want to do it from within Visual Studio?). If anyone does know of a good tutorial I would be interested in taking a look.

As I had to do this recently, and it took a lot of going backwards and forwards until I found a route that worked, I would write it up in case it is of help to anyone else.

This was built using:

1. Create solution

Create a new ASP.NET Core Web App (Model View Controller)

EF Core 5.0 create solution

2. Name the Web app 'EFCore5App'

EF Core 5.0 name web app

3. Additional Information

Most commercial websites or extranets are going to require either authenticated admin users, or authenticated members, or both, so by selecting 'Individual Accounts' from the beginning it causes the EF Core 5.0 dependencies to be included and makes the following steps easier.

EF Core 5.0 select authentication

4. Build and Run Solution

Check the solution builds and runs successfully.

5. The Web app will now contain the wiring for using EF Core 5.0.

The pertinent aspects being:

6. Go to Sql Server and create database 'efcore5db'

7. Apply the initial Identity Migration

EF Core 5.0 name web app

This will add the Identity and migrations tables to the database, and more importantly, confirm EF is configured correctly and migrations are working.

EF Core 5.0 name web app

8. Add Separate Repository Class Library

Add a new Class Library called Repository to the solution. This where we are going to move all our EF Core functionality to.

EF Core 5.0 name web app

Also add a Project Reference to this project from the Web app.

9. Move NuGet Packages to new class library

We will now start moving the EF Core 5.0 functionality from the Web app to the new Repository project.

The following packages are installed for EFCore5App:

EF Core 5.0 name web app

For each of the following three packages, select Repository and Install. Then select EFCore5App and Uninstall.

Also Install Microsoft.EntityFrameworkCore.Tools to Repository (leaving it still installed for the Web app).

10. Move Contents of Data Folder

Move all the contents of the \Data folder to the Repository class library and delete the Data folder in the Web app

Update the namespaces in files:

replace the '.Data' part of the namespace with '.Repository', e.g. EFCore5App.Data.Migrations to EFCore5App.Repository.Migrations.

In file Startup.cs add 'using EFCore5App.Repository;'

11. Build and Run Solution

Remove the 'using EFCore5App.Data;' statements that are no longer needed. Check the solution builds and runs successfully.

12. Add New Migration

In the Repositiry class library create a folder called 'entity'.

13. Create Data Entity/Model

Under entity create the first data model called ContentType (remove the .entity from the namespace).

EF Core 5.0 name web app

Copy model properties Id and Name.

EF Core 5.0 name web app

14. Add Entity/Model to Migration

In file ApplicationDbContext.cs add a DbSet for ContentType.

EF Core 5.0 name web app

15. Create Migration

The new migration should now be added to the Repository project:

EF Core 5.0 name web app

16. Complete

Table ContentType table should now have been created in the Sql Server database.

EF Core 5.0 name web app

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