.NET 7 Entity Framework/EF7 - Install And Code First Migrations

Introduction

In this article, we will discuss how to install .NET 7 Entity Framework / EF7: Install & Code First Migrations.

.NET 7 Entity Framework (EF7)

Entity Framework (EF) is an object-relational mapper (ORM) that enables developers to work with a database using objects and LINQ queries, rather than writing raw SQL queries. EF7 is the latest version of Entity Framework and is built for .NET 7 and the cloud.

Installing EF7

EF7 can be installed using the NuGet package manager. To install EF7, open the NuGet Package Manager console and run the following command,

Install-Package Microsoft.EntityFrameworkCore -Version 7.0.0-preview.7.20365.15

Alternatively, you can install EF7 using the dotnet command line interface (CLI),

dotnet add package Microsoft.EntityFrameworkCore --version 7.0.0-preview.7.20365.15

Code First Migrations

Code first migrations allow you to create a database from your EF7 model by writing code, rather than using a visual designer or writing SQL scripts. This can be useful when you want to automate the process of creating and updating a database, or when you want to version control your database schema.

To enable code first migrations, you need to install the EF7 tools using the NuGet Package Manager console,

Install-Package Microsoft.EntityFrameworkCore.Tools -Version 7.0.0-preview.7.20365.15

or the dotnet CLI,

dotnet add package Microsoft.EntityFrameworkCore.Tools --version 7.0.0-preview.7.20365.15

Next, we need to enable migrations by running the following command in the Package Manager console,

Enable-Migrations

This will create a Migrations folder in your project, containing a Configuration.cs file. This file allows you to specify the connection string and configure the database initializer.

To create a new migration, run the following command in the Package Manager console,

Add-Migration <MigrationName>

Replace <MigrationName> with a descriptive name for the migration. This will create a new migration class in the Migrations folder.

To apply the migration to the database, run the following command in the Package Manager console:

Update-Database

This will create or update the database based on the migration.

Example

To illustrate how code first migrations work in EF7, let's walk through an example of creating a simple database for a blog application.

First, create a new .NET 7 console project and install EF7 using the NuGet Package Manager console or the dotnet CLI as described above.

Next, create a class for the Post model,

public class Post
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }
    public DateTime CreatedAt { get; set; }
}

Then, create a BlogContext class that derives from DbContext and includes a DbSet for the Post model,

using Microsoft.Data.Entity;
namespace MyBlog.Models {
    public class BlogContext: DbContext {
        public DbSet < Post > Posts {
            get;
            set;
        }
    }
}

This BlogContext class can be used to perform database operations on the Post model, such as querying, inserting, updating, and deleting records.

To use this BlogContext class, you will need to configure the database connection in your application's configuration file, such as appsettings.json or web.config. You will also need to configure Entity Framework to use this BlogContext class as the database context.

Here is an example of how you might configure Entity Framework in a .NET 7 application:

using Microsoft.Data.Entity;
using Microsoft.Data.Entity.Infrastructure;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
namespace MyBlog {
    public class Startup {
        public Startup(IConfiguration configuration) {
            Configuration = configuration;
        }
        public IConfiguration Configuration {
            get;
        }
        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services) {
            services.AddEntityFramework().AddSqlServer().AddDbContext < BlogContext > (options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
            // Add other services here
        }
        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env) {
            // Add other middleware here
            app.UseMvc(routes => {
                routes.MapRoute(name: "default", template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

Conclusion

EF7 is a powerful ORM that allows developers to work with a database using objects and LINQ queries, and code first migrations provide a way to automate the process of creating and updating a database. By following the steps outlined in this article, you can easily install and use EF7 and code first migrations in your .NET 7 projects.