Step by step: .NET Core and Entity Framework Core

Today I’ll show you how to create a small console application with a Step by step: .NET Core and Entity Framework Core example.

First be aware of the following prerequisites:

Now let’s start:

Create a folder for your new project

Open a command promt an run

1mkdir efcore

Create the project

1cd efcore
2dotnet new

Create a settings file

Create an appsettings.json file to hold your connection string information. We’ll be using **SQLite **for this example, so add these lines:

1{
2  "ConnectionStrings": {
3    "Sample": "Data Source=sample.db"
4  }
5}

Modify the project file

Modify the project.json to add the EntityFrameworkCore dependencies and also specify that the appsettings.json file must be copied to the output (**buildOptions **section) so it becomes available to the application once you build it.

 1{
 2  "version": "1.0.0-*",
 3  "buildOptions": {
 4    "debugType": "portable",
 5    "emitEntryPoint": true,
 6    "copyToOutput": {
 7      "include": "appsettings.json"
 8    }
 9  },
10  "dependencies": {
11    "Microsoft.Extensions.Configuration": "1.0.0",
12    "Microsoft.Extensions.Configuration.Json": "1.0.0",
13    "Microsoft.EntityFrameworkCore": "1.0.0",
14    "Microsoft.EntityFrameworkCore.Sqlite": "1.0.0"
15  },
16  "frameworks": {
17    "netcoreapp1.0": {
18      "dependencies": {
19        "Microsoft.NETCore.App": {
20          "type": "platform",
21          "version": "1.0.0"
22        }
23      },
24      "imports": "dnxcore50"
25    }
26  }
27}

Restore packages

You just modified the project.json file with new dependencies so please restore the packages with the following command:

1dotnet restore

Create the Entity Framework context

Create a SampleContext.cs file and copy the following code

 1namespace ConsoleApplication
 2{
 3    using Microsoft.EntityFrameworkCore;
 4
 5    /// <summary>
 6    /// The entity framework context with a Students DbSet 
 7    /// </summary>
 8    public class StudentsContext : DbContext
 9    {
10        public StudentsContext(DbContextOptions<StudentsContext> options)
11            : base(options)
12        { }
13
14        public DbSet<Student> Students { get; set; }
15    }
16
17    /// <summary>
18    /// A factory to create an instance of the StudentsContext 
19    /// </summary>
20    public static class StudentsContextFactory
21    {
22        public static StudentsContext Create(string connectionString)
23        {
24            var optionsBuilder = new DbContextOptionsBuilder<StudentsContext>();
25            optionsBuilder.UseSqlite(connectionString);
26
27            // Ensure that the SQLite database and sechema is created!
28            var context = new StudentsContext(optionsBuilder.Options);
29            context.Database.EnsureCreated();
30
31            return context;
32        }
33    }
34
35    /// <summary>
36    /// A simple class representing a Student
37    /// </summary>
38    public class Student
39    {
40        public Student()
41        {
42        }
43
44        public int Id { get; set; }
45
46        public string Name { get; set; }
47
48        public string LastName { get; set; }
49    }
50}

Modify Program.cs

Replace the contents of the Program.cs file with the following code

 1namespace ConsoleApplication
 2{
 3    using System;
 4    using Microsoft.Extensions.Configuration;
 5
 6    public class Program
 7    {
 8        public static void Main(string[] args)
 9        {
10            // Enable to app to read json setting files
11            var builder = new ConfigurationBuilder()
12                .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);
13
14            var configuration = builder.Build();
15
16            // Get the connection string
17            string connectionString = configuration.GetConnectionString("Sample");
18
19            // Create a Student instance
20            var user = new Student() { Name = "Carlos", LastName = "Mendible" };
21
22            // Add and Save the student in the database
23            using (var context = StudentsContextFactory.Create(connectionString))
24            {
25                context.Add(user);
26                context.SaveChanges();
27            }
28
29            Console.WriteLine($"Student was saved in the database with id: {user.Id}");
30        }
31    }
32}

Build

Build the application with the following command

1dotnet build

Run

You are good to go so run the application

1dotnet run

You can get the code here: https://github.com/cmendible/dotnetcore.samples/tree/main/efcore.sqlite.console

Hope it helps!