EF Core 2.1 项目添加迁移 NullReferenceException

Question

我在一个最近转换为 dotnet core 2.1 的项目上获得 NullReferenceException。

我的 EF 库项目是 dotnet core 2.1。代码优先迁移。

CsvHelper 6.0.2
Microsoft.EntityFrameworkCore 2.1.0
Microsoft.EntityFrameworkCore.Design 2.1.0
Microsoft.EntityFrameworkCore.SqlServer 2.1.0
Microsoft.EntityFrameworkCore.Tools 2.1.0

添加迁移命令的输出

PM> add-migration -Name MyMigration -Context EscData01Context -Project Data\EscData01 -StartupProject PacmsTri -verbose
Using project 'Data\EscData01'.
Using startup project 'PacmsTri'.
Build started...
Build succeeded.
C:\Program Files\dotnet\dotnet.exe exec --depsfile C:\temp\PacmsTri\dev\***\source\PacmsTri\bin\Debug\netcoreapp2.1\PacmsTri.deps.json --additionalprobingpath "C:\Users\***\.nuget\packages" --additionalprobingpath "C:\Program Files\dotnet\sdk\NuGetFallbackFolder" --runtimeconfig C:\temp\PacmsTri\dev\***\source\PacmsTri\bin\Debug\netcoreapp2.1\PacmsTri.runtimeconfig.json "C:\Users\***\.nuget\packages\microsoft.entityframeworkcore.tools.1.0\tools\netcoreapp2.0\any\ef.dll" migrations add MyMigration --json --context EscData01Context --verbose --no-color --prefix-output --assembly C:\temp\PacmsTri\dev\****\source\PacmsTri\bin\Debug\netcoreapp2.1\EscData01.dll --startup-assembly C:\temp\PacmsTri\dev\****\source\PacmsTri\bin\Debug\netcoreapp2.1\PacmsTri.dll --project-dir C:\temp\PacmsTri\dev\****\source\Data\EscData01\ --language C# --working-dir C:\temp\PacmsTri\dev\****\source --root-namespace Sms.Office.Data.EscData01
Using assembly 'EscData01'.
Using startup assembly 'PacmsTri'.
Using application base 'C:\temp\PacmsTri\dev\***\source\PacmsTri\bin\Debug\netcoreapp2.1'.
Using working directory 'C:\temp\PacmsTri\dev\***\source\PacmsTri'.
Using root namespace 'Sms.Office.Data.EscData01'.
Using project directory 'C:\temp\PacmsTri\dev\***\source\Data\EscData01\'.
Finding DbContext classes...
Finding IDesignTimeDbContextFactory implementations...
Finding application service provider...
Finding IWebHost accessor...
Using environment 'Development'.
Using application service provider from IWebHost accessor on 'Program'.
Found DbContext 'AuthDbContext'.
Found DbContext 'DmsContext'.
Found DbContext 'EscData01Context'.
Found DbContext 'MailServicesContext'.
Found DbContext 'PmsDdContext'.
Finding DbContext classes in the project...
Using context 'EscData01Context'.
Microsoft.EntityFrameworkCore.Infrastructure[10403]
      Entity Framework Core 2.1.0-rtm-30799 initialized 'EscData01Context' using provider 'Microsoft.EntityFrameworkCore.SqlServer' with options: None
Finding design-time services for provider 'Microsoft.EntityFrameworkCore.SqlServer'...
Using design-time services from provider 'Microsoft.EntityFrameworkCore.SqlServer'.
Finding design-time services referenced by assembly 'PacmsTri'.
No referenced design-time services were found.
Finding IDesignTimeServices implementations in assembly 'PacmsTri'...
No design-time services were found.
System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.EntityFrameworkCore.Metadata.Internal.TableMapping.<>c.<GetRootType>b__10_0(IEntityType t)
   at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source, Func`2 predicate)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.TableMapping.GetRootType()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetSortedProperties(TableMapping target)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Add(TableMapping target, DiffContext diffContext)+MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.DiffCollection[T](IEnumerable`1 sources, IEnumerable`1 targets, DiffContext diffContext, Func`4 diff, Func`3 add, Func`3 remove, Func`4[] predicates)+MoveNext()
   at System.Linq.Enumerable.ConcatIterator`1.MoveNext()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.Sort(IEnumerable`1 operations, DiffContext diffContext)
   at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationsModelDiffer.GetDifferences(IModel source, IModel target)
   at Microsoft.EntityFrameworkCore.Migrations.Design.MigrationsScaffolder.ScaffoldMigration(String migrationName, String rootNamespace, String subNamespace, String language)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_1.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Object reference not set to an instance of an object.
PM>

我已尝试将 IDesignTimeServices 对象添加到我的启动项目，并尝试添加 IDesignTimeDbContextFactory。我还尝试使用相同的 dotnet 和 EF 版本号创建一个新的示例项目，指向相同的数据库并且能够生成上下文并成功创建迁移。所以我看不到的两个项目之间肯定有一些区别。

PM> add-migration MyMigration2 -Project ClassLibrary1 -StartupProject WebApplication20 -Context ESC_DATA01Context
Microsoft.EntityFrameworkCore.Infrastructure[10403]
      Entity Framework Core 2.1.0-rtm-30799 initialized 'ESC_DATA01Context' using provider 'Microsoft.EntityFrameworkCore.SqlServer' with options: None
To undo this action, use Remove-Migration.

非常感谢任何帮助。

更新：

我最初发帖说这个错误是由项目迁移到标准 2.0 引起的，但在将它转换回 dotnetcore2.1 后打消了这个想法并且错误仍然存在。

Answer 1

看起来这个错误是由我的 ModelSnapshot class 中不再存在的一些模型引用引起的。包括我从上下文中删除 AspNetCore.Identity 后留下的一些身份模型。

从我的 EscData01ContextModelSnapshot 中删除下面的代码解决了这个问题。

modelBuilder.Entity("Sms.Office.Data.EscData01.Models.ExcelTemplate", b =>
{
    b.HasOne("Sms.Office.Data.EscData01.Models.File", "File")
        .WithMany()
        .HasForeignKey("FileId")
        .OnDelete(DeleteBehavior.Cascade);
});
modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRoleClaim<string>", b =>
{
    b.HasOne("Sms.Office.Data.EscData01.Authentication.ApplicationRole")
        .WithMany()
        .HasForeignKey("RoleId")
        .OnDelete(DeleteBehavior.Cascade);
});
modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserClaim<string>", b =>
{
     b.HasOne("Sms.Office.Data.EscData01.Authentication.ApplicationUser")
         .WithMany()
         .HasForeignKey("UserId")
         .OnDelete(DeleteBehavior.Cascade);
});
modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserLogin<string>", b =>
{
     b.HasOne("Sms.Office.Data.EscData01.Authentication.ApplicationUser")
         .WithMany()
         .HasForeignKey("UserId")
         .OnDelete(DeleteBehavior.Cascade);
});
modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserRole<string>", b =>
{
     b.HasOne("Sms.Office.Data.EscData01.Authentication.ApplicationRole")
         .WithMany()
         .HasForeignKey("RoleId")
         .OnDelete(DeleteBehavior.Cascade);
     b.HasOne("Sms.Office.Data.EscData01.Authentication.ApplicationUser")
         .WithMany()
         .HasForeignKey("UserId")
         .OnDelete(DeleteBehavior.Cascade);
});   
modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityUserToken<string>", b =>
{
     b.HasOne("Sms.Office.Data.EscData01.Authentication.ApplicationUser")
         .WithMany()
         .HasForeignKey("UserId")
         .OnDelete(DeleteBehavior.Cascade);
});

EF Core 2.1 项目添加迁移 NullReferenceException

EF Core 2.1 project Add-Migration NullReferenceException

asp.net

entity-framework-core

entity-framework-core-2.1