实体框架app.config配置不会创建数据库

Question

I'm trying to use entity framework with code first method, but for some reason it does not create a database for me. I suppose the problem is in my app.config configuration file. I never used entity framework before. I have read similar posts on stackoverflow, but however I cannot solve my problem. I do not get any errors during compilation, but when I open microsoft sql server I don't see my database created.

This is my app.config file. I found this code online, but I don't know what should I write inside Database attribute.

<configuration>
  <configSections>
        <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    </configSections>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
  </startup>
  <appSettings>
    <add key="ipadress" value="127.0.0.1" />
    <add key="port" value="14000" />
  </appSettings>

  <connectionStrings>
    <add name="AVLdataContext" connectionString="Server=.\SQLEXPRESS;Database=Blogging;Integrated Security=True;"  providerName="System.Data.SqlClient"/>
  </connectionStrings>
</configuration>

Also here is my model class:

namespace TCPserver
{
    public class DataBaseModel
    {
        public static string LoadToDatabase(byte[] arr, string imei)
        {
            return ReversedBinaryReader.LoadToDatabase(arr, imei);
        }
    }

    public class AVLdataContext : DbContext
    {
        public DbSet<Datas> Data { get; set; }
        public DbSet<GPSelement> GPSelement { get; set; }
        public DbSet<IOelement> IOelement { get; set; }
    }
}

Here is my controller:

using (var db = new AVLdataContext())
{
    db.Data.Add(data);
    db.GPSelement.Add(data.Gps);
    db.IOelement.Add(data.Io);
    db.SaveChanges();
}

What am I doing wrong? I'm completely green at this.

Answer 1

You need to update the AVLdataContext to include a constructor calls base() with the connection string

public class AVLdataContext : DbContext
{
    public AVLdataContext ()
        : base("AVLdataContext")
    {

    }

    public DbSet<Datas> Data { get; set; }
    public DbSet<GPSelement> GPSelement { get; set; }
    public DbSet<IOelement> IOelement { get; set; }
}

Without this, EF has no way of knowing where the database is.

Have a look at this as well.

Answer 2

Try to open your package manager Console and write folowing commands:

Enable-Migrations
Add-Migration initial
Update-Database

This will enable migrations for your db, add first migration and create db.