Entity Framework Connection String

Question

I am creating a project using Entity Framework.

My question would be, how can I create a connectionString (for SQL Server for example) and set in my Dbcontext where it will get from the Web.config file?

Dbcontext

namespace Data
{
    public class DBContext : DbContext
    {
        public DBContext() : base("dbName")
        {

        }

        public DbSet<Usuarios> Clientes { get; set; }
        public DbSet<Vendedores> Produtos { get; set; }

    }
}

Answer 1

Your connectionStrings should look like this on the web.config:

To create in Localdb:

<connectionStrings>
    <add name="DefaultConnection" connectionString="Data Source=(LocalDb)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\Nome_Arquivo.mdf;Initial Catalog=Nome_Arquivo;Integrated Security=True" providerName="System.Data.SqlClient" />
  </connectionStrings>

To create in SQL Server (if installed):

  <connectionStrings>
    <add name="DefaultConnection" connectionString="Data Source=.\SQLEXPRESS;Initial Catalog=Nome_BD;Integrated Security=True" providerName="System.Data.SqlClient" />
  </connectionStrings>

The first connectionStrings string is automatically created on your web.config when you start a MVC project with EF. Check that it no longer exists before you create it, and if you wish, change to the second example.

You do not need to point in your Dbcontext. If you want the database to be already created (Codefirst), activate Migrations on Package Manager Console typing:

Enable-Migrations

After that the directory will appear Migrations in your project. Open the file Configuration.cs in that directory and activate the options below:

public Configuration()
    {
        AutomaticMigrationsEnabled = true;
        AutomaticMigrationDataLossAllowed = true;
    }

With these settings you can now use the command below on Package Manager Console:

Update-Database

This command will create your Database. The MDF file will appear in the folder App-Data (if you created a Localdb) and if you click Show all files can open it to view its database on Server-Explore.

If you created in SQL Server, just open Management Studio to see the database.

Your Dbcontext should look like this (already with the 2 Dbset of your question):

public class DBContext : DbContext
    {
        public DBContext()
            : base("DefaultConnection", throwIfV1Schema: false)
        {
        }

        public static DBContext Create()
        {
            return new ApplicationDbContext();
        }

        public DbSet<Usuarios> Clientes { get; set; }
        public DbSet<Vendedores> Produtos { get; set; }
    }