View source for Code First Approach

[[Category:MVC]]
[[Category:CSharp]]
[[Category:Entity Framework]]
[[Category:Database]]
[[Category:SQL]]

<pre style="width:80%; border: 2px solid red; font-weight:bold;">
♠ if you don't use data in startup page you can't see data tables as created. (it took 6 hours) 
</pre>

<pre style="width:80%; border: 2px solid red; font-weight:bold;">
♠ Code First includes derived classes even if only base class is defined as DbSet property. 
♠ (you don't need to add them to dbset if you create them with foreign keys)
</pre>

<pre style="width:80%; border: 2px solid red; font-weight:bold;">
♠ The default convention for primary key is that Code First would create a primary key 
♠ for a property if the property name is Id or <class name>Id (NOT case sensitive).
</pre>


 Install-Package EntityFramework -Pre -Version 6.0.0

in '''Model''' Folder Create '''Student.cs''' class
    
 using System; 
 using System.Collections.Generic;  
 namespace ContosoUniversity.Models 
 {
    public class Student 
    { 
      public int ID { get; set; } 
      public string LastName { get; set; } 
      public string FirstMidName { get; set; } 
      public DateTime EnrollmentDate { get; set; }  
      public virtual ICollection<Enrollment> Enrollments { get; set; } 
    } 
  }

in '''Model''' Folder Create '''Enrollment.cs''' class

 namespace ContosoUniversity.Models 
 {     
    public enum Grade     
    {         
      A, B, C, D, F     
    } 
 
    public class Enrollment     
    {         
      public int EnrollmentID { get; set; }
      public int CourseID { get; set; }
      public int StudentID { get; set; }
      public Grade? Grade { get; set; }
      public virtual Course Course { get; set; }
      public virtual Student Student { get; set; }     
    } 
 } 

in '''Model''' Folder Create '''Course.cs''' class

 using System.Collections.Generic; 
 using System.ComponentModel.DataAnnotations.Schema;
   
 namespace ContosoUniversity.Models 
 {     
   public class Course     
   {         
      [DatabaseGenerated(DatabaseGeneratedOption.None)]         
      public int CourseID { get; set; }   
      public string Title { get; set; }
      public int Credits { get; set; }
      public virtual ICollection<Enrollment> Enrollments { get; set; }     
    } 
 }

Create a folder in root as '''DAL''' 
Create '''BackOfficeContext.cs''' file in '''DAL'''

 using ContosoUniversity.Models; 
 using System.Data.Entity; 
 using System.Data.Entity.ModelConfiguration.Conventions;  
 
 namespace ContosoUniversity.DAL 
 {     
    public class SchoolContext : DbContext     
    {              
      public SchoolContext() : base("SchoolContext")         {         
    }          
    public DbSet<Student> Students { get; set; }
    public DbSet<Enrollment> Enrollments { get; set; }
    public DbSet<Course> Courses { get; set; }
 
    protected override void OnModelCreating(DbModelBuilder modelBuilder)         
    {             
      modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();         
    }     
   } 
 }   

Create a file named '''BackOfficeInitializer.cs''' in '''DAL''' folder

 using System; 
 using System.Collections.Generic; 
 using System.Linq; 
 using System.Web; 
 using System.Data.Entity; 
 using ContosoUniversity.Models;
  
 namespace ContosoUniversity.DAL 
 {     
   public class SchoolInitializer : System.Data.Entity. DropCreateDatabaseIfModelChanges<SchoolContext>     
   {         
      protected override void Seed(SchoolContext context)
      {             
        var students = new List<Student>
        {
 
         //---------------------------------------------------------------------------------------------------------
         // I think the correct syntax is this one below (ALI)
         //---------------------------------------------------------------------------------------------------------
          <b style="color:red;">new Student{) {FirstMidName="Carson",LastName="Alexander",EnrollmentDate=DateTime.Pa rse("2005-09-01")},</b>         
         //---------------------------------------------------------------------------------------------------------
 
          new Student{FirstMidName="Carson",LastName="Alexander",EnrollmentDate=DateTime.Pa rse("2005-09-01")},             
          new Student{FirstMidName="Meredith",LastName="Alonso",EnrollmentDate=DateTime.Par se("2002-09-01")},             
          new Student{FirstMidName="Arturo",LastName="Anand",EnrollmentDate=DateTime.Parse( "2003-09-01")},             
          new Student{FirstMidName="Gytis",LastName="Barzdukas",EnrollmentDate=DateTime.Par se("2002-09-01")}, 
          new Student{FirstMidName="Yan",LastName="Li",EnrollmentDate=DateTime.Parse("2002- 09-01")},             
          new Student{FirstMidName="Peggy",LastName="Justice",EnrollmentDate=DateTime.Parse ("2001-09-01")},             
          new Student{FirstMidName="Laura",LastName="Norman",EnrollmentDate=DateTime.Parse( "2003-09-01")},             
          new Student{FirstMidName="Nino",LastName="Olivetto",EnrollmentDate=DateTime.Parse ("2005-09-01")}             
         };  
         students.ForEach(s => context.Students.Add(s));
         context.SaveChanges();             
 
         var courses = new List<Course>             
         {             
            new Course{CourseID=1050,Title="Chemistry",Credits=3,},             
            new Course{CourseID=4022,Title="Microeconomics",Credits=3,},     
            new Course{CourseID=4041,Title="Macroeconomics",Credits=3,},   
            new Course{CourseID=1045,Title="Calculus",Credits=4,},             	
            new Course{CourseID=3141,Title="Trigonometry",Credits=4,},          
            new Course{CourseID=2021,Title="Composition",Credits=3,},   
            new Course{CourseID=2042,Title="Literature",Credits=4,}             
          };
          courses.ForEach(s => context.Courses.Add(s));  
          context.SaveChanges();             

          var enrollments = new List<Enrollment>             
          {             
          new Enrollment{StudentID=1,CourseID=1050,Grade=Grade.A},     
          new Enrollment{StudentID=1,CourseID=4022,Grade=Grade.C},        
          new Enrollment{StudentID=1,CourseID=4041,Grade=Grade.B},     
          new Enrollment{StudentID=2,CourseID=1045,Grade=Grade.B},    	  
          new Enrollment{StudentID=2,CourseID=3141,Grade=Grade.F},      
          new Enrollment{StudentID=2,CourseID=2021,Grade=Grade.F},      
          new Enrollment{StudentID=3,CourseID=1050},             
          new Enrollment{StudentID=4,CourseID=1050,},             
          new Enrollment{StudentID=4,CourseID=4022,Grade=Grade.F},           
          new Enrollment{StudentID=5,CourseID=4041,Grade=Grade.C},      
          new Enrollment{StudentID=6,CourseID=1045},             
          new Enrollment{StudentID=7,CourseID=3141,Grade=Grade.A},             
        };             
        enrollments.ForEach(s => context.Enrollments.Add(s));     
        context.SaveChanges();         
        }     
      } 
  } 


in '''Web.Config''' file...
 <entityFramework>   
    <contexts>     
      <context type="ContosoUniversity.DAL.SchoolContext, ContosoUniversity">  
        <databaseInitializer type="ContosoUniversity.DAL.SchoolInitializer, ContosoUniversity" />     
      </context>   
    </contexts>   
		
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">     
      <parameters>       
        <parameter value="v11.0" />     
      </parameters>   
    </defaultConnectionFactory>   
    <providers>     
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />   
      </providers> 
    </entityFramework>

And Again in '''web.config''' file 

 <connectionStrings>     
   <add name="SchoolContext" connectionString="AttachDBFilename=|DataDirectory|\ContosoUniversity1.mdf;Data Source=(LocalDb)\v11.0;Initial Catalog=ContosoUniversity1;Integrated Security=SSPI;" providerName="System.Data.SqlClient"/> 
 </connectionStrings> 
 
 <appSettings>   
   <add key="webpages:Version" value="3.0.0.0" />   
   <add key="webpages:Enabled" value="false" />   
   <add key="ClientValidationEnabled" value="true" />   
   <add key="UnobtrusiveJavaScriptEnabled" value="true" /> 
 </appSettings>

== The model backing the context has changed since the database was created Problem ==
in Global.asax 
 using System.Data.Entity;
 using LogicBO.DAL;
 using LogicBO.Models;
 ......       
 protected void Application_Start()
 { 
 Database.SetInitializer<BoContext>(new DropCreateDatabaseIfModelChanges<BoContext>());

== The specified type member 'Date' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties ==
 .Where(q => DbFunctions.TruncateTime(q.DateStart) >= DateTime.Now.Date)