EF Core Extras Database Setup

Create Data Model

Model is a collection of classes to interact with the database. We will create a simple class called Student and add the following code.

public class Employee
{
    public int EmployeeId { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
    public int Salary { get; set; }
}

Create Database Context

The database context class provides the main functionality to coordinate Entity Framework with a given data model.

• You can create this class by deriving from the Microsoft.EntityFrameworkCore.DbContext class.
• In your code, you can specify which entities are included in the data model.
• You can also customize certain Entity Framework behavior.

So let's add a new class EmployeeContext, and replace the following code.

public class EmployeeContext : DbContext
{
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer(@"Data Source=(localdb)\ProjectsV13;Initial Catalog=EmployeeContextDb;");
    }

    public DbSet<Employee> Employees { get; set; }
}

This code creates a DbSet property for each entity set. In Entity Framework terminology, an entity set typically corresponds to a database table, and an entity corresponds to a row in the table.

Initialize Database

The Entity Framework will create an empty database for you. So we need to write a method that's called after the database is created to populate it with test data.

public static void Initialize()
{
    using (EmployeeContext context = new EmployeeContext())
    {
        context.Database.EnsureDeleted();
        context.Database.EnsureCreated();

        var employees = new List<Employee>
        {
            new Employee { Name="Carson Alexander", Age = 32, Salary = 10000 },
            new Employee { Name="Meredith Alonso", Age = 55, Salary = 30000 },
            new Employee { Name="Arturo Anand", Age = 42, Salary = 23000 },
            new Employee { Name="Gytis Barzdukas", Age = 31, Salary = 10500 },
            new Employee { Name="Yan Li", Age = 33, Salary = 18000 },
        };

        employees.ForEach(a => context.Employees.Add(a));
        context.SaveChanges();
    }
}

• The above code creates a database when needed and loads test data into the new database.
• It also checks if there are any authors in the database, and if not, it assumes the database is new and needs to be seeded with test data.

In the Main method, replace the following code.

static void Main(string[] args)
{
    Initialize();
    using (EmployeeContext context = new EmployeeContext())
    {
        int employees = context.Employees.Count();

        Console.WriteLine("Total Employees: {0}", employees);
    }
}

Now when you run your application for the first time, the database will be created, and seeded with test data and you will see the following output.

Total Employees: 5