jerryh91 jerryh91 - 3 months ago 22
ASP.NET (C#) Question

Data Initializer Cannot be converted in ASP.NET MVC?

I'm following the tutorial on: http://www.asp.net/mvc/overview/getting-started/getting-started-with-ef-using-mvc/creating-an-entity-framework-data-model-for-an-asp-net-mvc-application. I've added my data in SchoolInitializer.cs, however, I'm getting the following error:


Object of type 'ContosoUniversity.DAL.SchoolInitializer' cannot be converted to type 'System.Data.Entity.IDatabaseInitializer`1[ContosoUniversity.DAL.SchoolContext]'.


Web.config:

<contexts>
<context type="ContosoUniversity.DAL.SchoolContext, ContosoUniversity">
<databaseInitializer type="ContosoUniversity.DAL.SchoolInitializer, ContosoUniversity" />
</context>
</contexts>


SchoolInitializer.cs: The tutorial has Seed() override declared. When I added "override", it said


Error 1 'ContosoUniversity.DAL.SchoolInitializer.Seed(ContosoUniversity.DAL.SchoolContext)': no suitable method found to override


using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using ContosoUniversity.Models;

namespace ContosoUniversity.DAL
{
//When accessing DB initially for every run. If there's a difference between database to the model (SchoolContext, Entity Class)
//Drops and recreates Database with data in SchoolInitializer

//In Web.config: add <context> </context> to let Entity Framework use SchoolInitializer
public class SchoolInitializer
{
protected void Seed(SchoolContext context)
{
var students = new List<Student>
{
new Student{FirstMidName="Carson",LastName="Alexander",EnrollmentDate=DateTime.Parse("2005-09-01")},
new Student{FirstMidName="Meredith",LastName="Alonso",EnrollmentDate=DateTime.Parse("2002-09-01")},
new Student{FirstMidName="Arturo",LastName="Anand",EnrollmentDate=DateTime.Parse("2003-09-01")},
new Student{FirstMidName="Gytis",LastName="Barzdukas",EnrollmentDate=DateTime.Parse("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")}
};

//Add entities to DbSet (entity set)
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();
}
}
}

Answer

Replace following line

public class SchoolInitializer

either with

public class SchoolInitializer: DropCreateDatabaseIfModelChanges<SchoolContext>

or with

public class SchoolInitializer: DropCreateDatabaseAlways<SchoolContext>