c# - 努力.Exceptions.EffortException : Database has not been initialized - after non commited update?

Question

为什么会出现这个异常？这是错误吗？

我正在使用 EF 测试库 Effort 创建我的数据库的内存实例并遇到这个有趣的场景:

1. 打开DbContext1
2. 将项目添加到表(不保存)
3. 关闭DbContext1
4. 打开DbContext2
5. 计算表中的项目数

Effort.Exceptions.EffortException:数据库尚未初始化。

但是，如果我也在 DbContext1 中执行计数(第 5 步)，那么 DbContext2 中的计数不会失败吗？

完整代码:

public void TestEF()
{
   var factory = new InMemoryMyApplicationDbContextFactory();

   using (var db = factory.CreateDbContext())
   {
      //uncomment this line to prevent exception - why????
      //db.Orders.Count();

      db.Orders.Add(new Order{ Id = Guid.NewGuid() }); 

      // intentionally do not call db.SaveChanges()
   }

   using (var db = factory.CreateDbContext())
   {
      // throws an exception if no read was performed above
      db.Orders.Count();
   }    
}    

完全异常:

Effort.Exceptions.EffortException : Database has not been initialized.

If using CodeFirst try to add the following line:
   context.Database.CreateIfNotExists()
 at System.Data.Entity.Core.EntityClient.Internal.EntityCommandDefinition.ExecuteStoreCommands(EntityCommand entityCommand, CommandBehavior behavior)
 at System.Data.Entity.Core.Objects.Internal.ObjectQueryExecutionPlan.Execute[TResultType](ObjectContext context, ObjectParameterCollection parameterValues)
 at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
 at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass7.<GetResults>b__5()
 at System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
 at System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0()
 at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
 at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)        

Answer 1

我接受了异常消息中提到的建议，并在 using 语句中将以下行添加到我的测试中

    db.Database.CreateIfNotExists();

这对我有用。