Question

显然，当我向另一个现有模型添加新模型和关系时，它不会正确地支持迁移。即使将创建迁移文件，也会显示一大块错误。

fail: Microsoft.EntityFrameworkCore.Query[10100]
      An exception occurred in the database while iterating the results of a query for context type 'CounterCore.Data.CounterDbContext'.
      System.NullReferenceException: Object reference not set to an instance of an object.
         at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.System.IObserver<System.Collections.Generic.KeyValuePair<System.String,System.Object>>.OnNext(KeyValuePair`2 keyValuePair)
         at System.Diagnostics.DiagnosticListener.Write(String name, Object value)
         at Microsoft.EntityFrameworkCore.Internal.CoreLoggerExtensions.QueryIterationFailed(IDiagnosticsLogger`1 diagnostics, Type contextType, Exception exception)
         at Microsoft.EntityFrameworkCore.Query.Internal.AsyncLinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.<MoveNext>d__5.MoveNext()
      --- End of stack trace from previous location where exception was thrown ---
         at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
         at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
         at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
         at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<ExecuteSingletonAsyncQuery>d__23`1.MoveNext()
System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.System.IObserver<System.Collections.Generic.KeyValuePair<System.String,System.Object>>.OnNext(KeyValuePair`2 keyValuePair)
   at System.Diagnostics.DiagnosticListener.Write(String name, Object value)
   at Microsoft.EntityFrameworkCore.Internal.CoreLoggerExtensions.QueryIterationFailed(IDiagnosticsLogger`1 diagnostics, Type contextType, Exception exception)
   at Microsoft.EntityFrameworkCore.Query.Internal.AsyncLinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.<MoveNext>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<ExecuteSingletonAsyncQuery>d__23`1.MoveNext()
fail: Microsoft.EntityFrameworkCore.Query[10100]
      An exception occurred in the database while iterating the results of a query for context type 'CounterCore.Data.CounterDbContext'.
      System.NullReferenceException: Object reference not set to an instance of an object.
         at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.System.IObserver<System.Collections.Generic.KeyValuePair<System.String,System.Object>>.OnNext(KeyValuePair`2 keyValuePair)
         at System.Diagnostics.DiagnosticListener.Write(String name, Object value)
         at Microsoft.EntityFrameworkCore.Internal.CoreLoggerExtensions.QueryIterationFailed(IDiagnosticsLogger`1 diagnostics, Type contextType, Exception exception)
         at Microsoft.EntityFrameworkCore.Query.Internal.AsyncLinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.<MoveNext>d__5.MoveNext()
      --- End of stack trace from previous location where exception was thrown ---
         at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
         at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
         at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
         at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<ExecuteSingletonAsyncQuery>d__23`1.MoveNext()
System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.System.IObserver<System.Collections.Generic.KeyValuePair<System.String,System.Object>>.OnNext(KeyValuePair`2 keyValuePair)
   at System.Diagnostics.DiagnosticListener.Write(String name, Object value)
   at Microsoft.EntityFrameworkCore.Internal.CoreLoggerExtensions.QueryIterationFailed(IDiagnosticsLogger`1 diagnostics, Type contextType, Exception exception)
   at Microsoft.EntityFrameworkCore.Query.Internal.AsyncLinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.<MoveNext>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<ExecuteSingletonAsyncQuery>d__23`1.MoveNext()
An exception occurred in the database while iterating the results of a query for context type 'CounterCore.Data.CounterDbContext'.
System.NullReferenceException: Object reference not set to an instance of an object.
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.System.IObserver<System.Collections.Generic.KeyValuePair<System.String,System.Object>>.OnNext(KeyValuePair`2 keyValuePair)
   at System.Diagnostics.DiagnosticListener.Write(String name, Object value)
   at Microsoft.EntityFrameworkCore.Internal.CoreLoggerExtensions.QueryIterationFailed(IDiagnosticsLogger`1 diagnostics, Type contextType, Exception exception)
   at Microsoft.EntityFrameworkCore.Query.Internal.AsyncLinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.<MoveNext>d__5.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<ExecuteSingletonAsyncQuery>d__23`1.MoveNext()

所以这就是我做的事情

用户类：

public class User : IdentityUser<long>
{
    [MaxLength(20)]
    public string ReferralCode { get; set; }

    public ICollection<UserReferral> Referrals { get; set; }
}

UserReferral Class：

public class UserReferral : BaseEntityModel
    {
        public long ReferredUserId { get; set; }

        public string ReferralCode { get; set; }

        public virtual User ReferredUser { get; set; }
    }

在DbContext中：我只是为用户推荐添加了一个新实体，

            builder.Entity<UserReferral>(entity =>
            {
                entity.HasKey(ur => ur.ReferredUserId).HasName("UserReferral_PK_Id");

                entity.HasOne(ur => ur.ReferredUser).WithMany().HasForeignKey(ur => ur.ReferredUserId).OnDelete(DeleteBehavior.Restrict);
            });

用户实体在create上随机生成字符串的属性。相信我，我试着在3天内解决这个问题5-10次，所以我尝试过无数次重组。

entity.HasAlternateKey(u => u.ReferralCode).HasName("User_AK_ReferralCode");
                entity.Property(u => u.ReferralCode).HasDefaultValue(RandomGenerator.GenerateString());

关系的DbContext照常完成，第一次面对这个问题。

dotnet ef migrations：刚刚添加的列名无效

0 个答案: