Code First Approach In ASP.NET Core MVC With EF Core Migration

namespace CodeFirstMigration.Context
{
    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Address { get; set; }
        public string CompanyName { get; set; }
        public string Designation { get; set; }
    }
}

using Microsoft.EntityFrameworkCore;
namespace CodeFirstMigration.Context
{
    public class EmployeeDbContext : DbContext
    {
        public EmployeeDbContext(DbContextOptions options) : base(options)
        {
        }
        public DbSet<Employee> Employees { get; set; }
    }
}

{
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Warning"
    }
  },
  "ConnectionStrings": {
    "myconn": "server=ABC\\SQLEXPRESS2012; database=EmployeeDB;Trusted_Connection=True;"
  }
}

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc();
    services.AddDbContext<EmployeeDbContext>(item => 
        item.UseSqlServer(Configuration.GetConnectionString("myconn")));
}

Once the add migration command executes successfully, it creates a folder name as ‘Migration’ in the project and creates the class with the same name [MigrationName] as we have provided while executing the add migration command with some name. Here you can see the table structure based on your Model (Employee), which is ready to generate the database.

using Microsoft.EntityFrameworkCore.Metadata;
using Microsoft.EntityFrameworkCore.Migrations;
namespace CodeFirstMigration.Migrations
{
    public partial class initialmigration : Migration
    {
        protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.CreateTable(
                name: "Employees",
                columns: table => new
                {
                    EmployeeId = table.Column<int>(nullable: false)
                        .Annotation("SqlServer:ValueGenerationStrategy", SqlServerValueGenerationStrategy.IdentityColumn),
                    Name = table.Column<string>(nullable: true),
                    Address = table.Column<string>(nullable: true),
                    CompanyName = table.Column<string>(nullable: true),
                    Designation = table.Column<string>(nullable: true)
                },
                constraints: table =>
                {
                    table.PrimaryKey("PK_Employees", x => x.EmployeeId);
                });
        }
        protected override void Down(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.DropTable(
                name: "Employees");
        }
    }
}

We have only created the migration script which is responsible for creating the database and its table. But we've not created the actual database and tables. So, let's execute the migration script and generate the database and tables. Therefore, to execute the migration scripts we have to execute the ‘update-database’ command. So, let's perform it as follows.

For now, we have only one migration script available which is why we are not providing the name of the migration. If we have multiple migration scripts, then we have to provide the name along with the command as follows.

Update-database migrationname

Once the above command executes successfully, we just need to go to SQL Server Management Studio log in with Windows Authentication, and see the Database. You will find the database, table, and Entity Framework Migration history table as follows.

Now, let's modify the Employee model and add a new property as Salary with float type as follows.

namespace CodeFirstMigration.Context
{
    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Address { get; set; }
        public string CompanyName { get; set; }
        public string Designation { get; set; }
        public float Salary { get; set; }
    }
}

Move to the package manager console and run the following command to add a migration, this time we have given the name of the migration as 'addedsalary'.

Add-migration addedsalary

Once the above command execution is completed, it will create a new class for the migration name as follows. Here we can see, the migration builder has the configuration for adding a new column as salary.

using Microsoft.EntityFrameworkCore.Migrations;
namespace CodeFirstMigration.Migrations
{
    public partial class addedsalary : Migration
    {
        protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.AddColumn<float>(
                name: "Salary",
                table: "Employees",
                nullable: false,
                defaultValue: 0f);
        }
        protected override void Down(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.DropColumn(
                name: "Salary",
                table: "Employees");
        }
    }
}

For updating the table in the database with the new column as salary, we have to run the following command for updating the database.

Update-database addedsalary

Once the above update database command will execute successfully, just check the database's table. You will find the new column has been added to the Employees table as salary.

Now, let's see how to seed some dummy data into the table. So, move to EmployeeDbContext class and override the DbContext method 'OnModelCreating'. Using the help of the ModelBuilder, we can add some dummy data for the Employees table as follows.

using Microsoft.EntityFrameworkCore;
namespace CodeFirstMigration.Context
{
    public class EmployeeDbContext : DbContext
    {
        public EmployeeDbContext(DbContextOptions options) : base(options)
        {
        }
        public DbSet<Employee> Employees { get; set; }
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Employee>().HasData(
                new Employee { EmployeeId = 1, Name = "John", Designation = "Developer", Address = "New York", CompanyName = "XYZ Inc", Salary = 30000 },
                new Employee { EmployeeId = 2, Name = "Chris", Designation = "Manager", Address = "New York", CompanyName = "ABC Inc", Salary = 50000 },
                new Employee { EmployeeId = 3, Name = "Mukesh", Designation = "Consultant", Address = "New Delhi", CompanyName = "XYZ Inc", Salary = 20000 }
            );
        }
    }
}

So, above we have already prepared the data for seeding. Now, let's add it to migration using the following command.

Add-migration seeddata

Once the above command executes successfully, we can see the following seed data class will be generated with insert data configuration. Here we are defining the table name in which data should be added, columns, and their respective values.

using Microsoft.EntityFrameworkCore.Migrations;
namespace CodeFirstMigration.Migrations
{
    public partial class seeddata : Migration
    {
        protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.InsertData(
                table: "Employees",
                columns: new[] { "EmployeeId", "Address", "CompanyName", "Designation", "Name", "Salary" },
                values: new object[] { 1, "New York", "XYZ Inc", "Developer", "John", 30000f });
            migrationBuilder.InsertData(
                table: "Employees",
                columns: new[] { "EmployeeId", "Address", "CompanyName", "Designation", "Name", "Salary" },
                values: new object[] { 2, "New York", "ABC Inc", "Manager", "Chris", 50000f });
            migrationBuilder.InsertData(
                table: "Employees",
                columns: new[] { "EmployeeId", "Address", "CompanyName", "Designation", "Name", "Salary" },
                values: new object[] { 3, "New Delhi", "XYZ Inc", "Consultant", "Mukesh", 20000f });
        }
        protected override void Down(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.DeleteData(
                table: "Employees",
                keyColumn: "EmployeeId",
                keyValue: 1);
            migrationBuilder.DeleteData(
                table: "Employees",
                keyColumn: "EmployeeId",
                keyValue: 2);
            migrationBuilder.DeleteData(
                table: "Employees",
                keyColumn: "EmployeeId",
                keyValue: 3);
        }
    }
}

So, let's update the database with the generated migration class using the following command.

Update-database seeddata

Once the above command is executed successfully in the Package Manager Console, just move to the database and refresh the table. You will find the same dummy data that we have defined in migration has been updated in the table.

Conclusion

So, today we have learned how to implement the code first approach in the Asp.Net Core MVC project using Entity Framework Core Migration.

I hope this post will help you. Please put your feedback using comments which helps me to improve myself for the next post. If you have any doubts please ask your doubts or query in the comment section and If you like this post, please share it with your friends. Thanks