Question

我创建了具有简单登录和注册功能的ASP .NET MVC应用程序，并尝试使用“代码优先”方法创建Entity Framework 6模型。我正在使用LocalDb创建数据库。但是，添加

时出现以下异常

<contexts>
  <context type="WebApplication1.DAL.ProjectContext, WebApplication1">
    <databaseInitializer type="WebApplication1.DAL.ProjectInitializer, WebApplication1"/>
  </context>
</contexts>

到Web.config文件。例外如下：

大多数堆栈跟踪为：

[TypeLoadException: Could not load type 'WebApplication1.DAL.ProjectContext' from assembly 'WebApplication1'.]
System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName, ObjectHandleOnStack type) +0
   System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName) +106
   System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) +62
   System.Type.GetType(String typeName, Boolean throwOnError) +46
   System.Data.Entity.Internal.InitializerConfig.TryGetInitializer(Type requiredContextType, String contextTypeName, String initializerTypeName, Boolean isDisabled, Func`1 initializerArgs, Func`3 exceptionMessage) +47

[InvalidOperationException: Failed to set database initializer of type 'WebApplication1.DAL.ProjectInitializer, WebApplication1' for DbContext type 'WebApplication1.DAL.ProjectContext, WebApplication1' specified in the application configuration. See inner exception for details.]
   System.Data.Entity.Internal.InitializerConfig.TryGetInitializer(Type requiredContextType, String contextTypeName, String initializerTypeName, Boolean isDisabled, Func`1 initializerArgs, Func`3 exceptionMessage) +327
   System.Data.Entity.Internal.<>c__DisplayClass6.<TryGetInitializerFromEntityFrameworkSection>b__1(ContextElement e) +276
   System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +223

这是ProjectContext.cs代码：

namespace WebApplication1.Models.DAL{
using System;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using WebApplication1.Models;
using WebApplication1.Models.DAL;

public partial class ProjectContext : DbContext
{
    public ProjectContext(): base()
    {

    }
    public DbSet<PIP> PIP { get; set; }
    public DbSet<Project> Project { get; set; }

}
}

这是ProjectInitializer.cs代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Data.Entity;
using WebApplication1.Models;

namespace WebApplication1.Models.DAL
{
    public class ProjectInitializer:System.Data.Entity.DropCreateDatabaseIfModelChanges<ProjectContext>
    {
        protected override void Seed(ProjectContext context)
        {
            var projects = new List<Project>
            {
                new Project{ ProjectID=1, Name="New ADM", StartDate=new DateTime(2017,1,10), EndDate=new DateTime(2017,2,10),},
                new Project{ ProjectID=2, Name="New ADM", StartDate=new DateTime(2016,5,20), EndDate=new DateTime(2016,6,20),},
                new Project{ ProjectID=3, Name="New ADM", StartDate=new DateTime(2015,8,30), EndDate=new DateTime(2015,9,30),}
            };

            projects.ForEach(pr => context.Project.Add(pr));
            context.SaveChanges();

            var PIP = new List<PIP>
            {
                new PIP{ PIPID=1, ProjectID=1 },
                new PIP{ PIPID=2, ProjectID=2 },
                new PIP{ PIPID=3, ProjectID=3 },
            };
            PIP.ForEach(pip => context.PIP.Add(pip));
            context.SaveChanges();

            Database.SetInitializer<ProjectContext>(new ProjectInitializer());

        }
    }
}

Answer 1

在创建代码第一个实体框架应用程序时，无需添加上下文：

在“代码优先”方法中，您专注于自己的领域应用程序并开始为您的域实体创建类比先设计您的数据库，然后创建类符合您的数据库设计

这意味着，您不需要上下文（设计器）来访问您的数据库，您可以创建自己的类来与您的数据库进行通信。

请先在entityframework tutorial网站上阅读有关代码的更多信息。

Answer 2

您为ProjectContext中的ProjectInitializer和web.config类使用了错误的命名空间，它应该是WebApplication1.Models.DAL而不是WebApplication1.DAL。

<contexts>
  <context type="WebApplication1.Models.DAL.ProjectContext, WebApplication1">
    <databaseInitializer type="WebApplication1.Models.DAL.ProjectInitializer, WebApplication1"/>
  </context>
</contexts>

ASP .NET实体框架数据库未初始化

2 个答案: