Step by step: .NET Core and Entity Framework Core
Categories:
3 minute read
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:
| **OS** | **Prerequisites** |
| Windows | Windows: You must have .NET Core SDK for Windows or both Visual Studio 2015 Update 3* and .NET Core 1.0 for Visual Studio installed. |
| linux, mac or docker | checkout .NET Core |
Now let’s start:
Create a folder for your new project
Open a command promt an run
mkdir efcore
Create the project
cd efcore
dotnet 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:
{
"ConnectionStrings": {
"Sample": "Data Source=sample.db"
}
}
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.
{
"version": "1.0.0-*",
"buildOptions": {
"debugType": "portable",
"emitEntryPoint": true,
"copyToOutput": {
"include": "appsettings.json"
}
},
"dependencies": {
"Microsoft.Extensions.Configuration": "1.0.0",
"Microsoft.Extensions.Configuration.Json": "1.0.0",
"Microsoft.EntityFrameworkCore": "1.0.0",
"Microsoft.EntityFrameworkCore.Sqlite": "1.0.0"
},
"frameworks": {
"netcoreapp1.0": {
"dependencies": {
"Microsoft.NETCore.App": {
"type": "platform",
"version": "1.0.0"
}
},
"imports": "dnxcore50"
}
}
}
Restore packages
You just modified the project.json file with new dependencies so please restore the packages with the following command:
dotnet restore
Create the Entity Framework context
Create a SampleContext.cs file and copy the following code
namespace ConsoleApplication
{
using Microsoft.EntityFrameworkCore;
/// <summary>
/// The entity framework context with a Students DbSet
/// </summary>
public class StudentsContext : DbContext
{
public StudentsContext(DbContextOptions<StudentsContext> options)
: base(options)
{ }
public DbSet<Student> Students { get; set; }
}
/// <summary>
/// A factory to create an instance of the StudentsContext
/// </summary>
public static class StudentsContextFactory
{
public static StudentsContext Create(string connectionString)
{
var optionsBuilder = new DbContextOptionsBuilder<StudentsContext>();
optionsBuilder.UseSqlite(connectionString);
// Ensure that the SQLite database and sechema is created!
var context = new StudentsContext(optionsBuilder.Options);
context.Database.EnsureCreated();
return context;
}
}
/// <summary>
/// A simple class representing a Student
/// </summary>
public class Student
{
public Student()
{
}
public int Id { get; set; }
public string Name { get; set; }
public string LastName { get; set; }
}
}
Modify Program.cs
Replace the contents of the Program.cs file with the following code
namespace ConsoleApplication
{
using System;
using Microsoft.Extensions.Configuration;
public class Program
{
public static void Main(string[] args)
{
// Enable to app to read json setting files
var builder = new ConfigurationBuilder()
.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);
var configuration = builder.Build();
// Get the connection string
string connectionString = configuration.GetConnectionString("Sample");
// Create a Student instance
var user = new Student() { Name = "Carlos", LastName = "Mendible" };
// Add and Save the student in the database
using (var context = StudentsContextFactory.Create(connectionString))
{
context.Add(user);
context.SaveChanges();
}
Console.WriteLine($"Student was saved in the database with id: {user.Id}");
}
}
}
Build
Build the application with the following command
dotnet build
Run
You are good to go so run the application
dotnet run
You can get the code here: https://github.com/cmendible/dotnetcore.samples/tree/main/efcore.sqlite.console
Hope it helps!