EF - "Update-Database"导致Sequence包含多个元素

Question

我刚刚完成了模型的修改,在包管理器控制台和BOOM中运行了"Update-Database"!我收到了"序列包含多个元素"错误.通过控制台扫描后,它确实说明No pending explicit migrations.了自从我重命名某些模型以来哪个显然是错误的.我也发现了一个SingleOrDefault电话,我不知道它来自哪里.我评论了我的种子方法,因此不会导致它

    No pending explicit migrations.
System.InvalidOperationException: Sequence contains more than one element
   at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable`1 source)
   at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.<>c__DisplayClass280.<IndexesEqual>b__27d(String c)
   at System.Linq.Enumerable.<>c__DisplayClass7_0`3.<CombineSelectors>b__0(TSource x)
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Linq.Enumerable.SequenceEqual[TSource](IEnumerable`1 first, IEnumerable`1 second, IEqualityComparer`1 comparer)
   at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.IndexesEqual(ConsolidatedIndex consolidatedIndex1, ConsolidatedIndex consolidatedIndex2, ICollection`1 renamedColumns)
   at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.<>c__DisplayClass271.<FindAddedIndexes>b__26d(ConsolidatedIndex i1, ConsolidatedIndex i2)
   at System.Data.Entity.Utilities.DynamicEqualityComparer`1.Equals(T x, T y)
   at System.Linq.Set`1.Find(TElement value, Boolean add)
   at System.Linq.Enumerable.<ExceptIterator>d__72`1.MoveNext()
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.Diff(ModelMetadata source, ModelMetadata target, Lazy`1 modificationCommandTreeGenerator, MigrationSqlGenerator migrationSqlGenerator, String sourceModelVersion, String targetModelVersion)
   at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.Diff(XDocument sourceModel, XDocument targetModel, Lazy`1 modificationCommandTreeGenerator, MigrationSqlGenerator migrationSqlGenerator, String sourceModelVersion, String targetModelVersion)
   at System.Data.Entity.Migrations.DbMigrator.IsModelOutOfDate(XDocument model, DbMigration lastMigration)
   at System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
   at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
   at System.Data.Entity.Migrations.DbMigrator.UpdateInternal(String targetMigration)
   at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClassc.<Update>b__b()
   at System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
   at System.Data.Entity.Migrations.Infrastructure.MigratorBase.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
   at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration)
   at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration)
   at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.Run()
   at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
   at System.Data.Entity.Migrations.Design.ToolingFacade.Update(String targetMigration, Boolean force)
   at System.Data.Entity.Migrations.UpdateDatabaseCommand.<>c__DisplayClass2.<.ctor>b__0()
   at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
Sequence contains more than one element

编辑 经过一些挖掘,发现当EF查询_MigrationHistory表时发生错误.但是我不想期待记录,因为我想更新架构？

是否将模型移动到另一个项目是否有效？

编辑再次 我厌倦了找到导致问题的原因,所以我做了一个快速的解决方法

1. 创建数据的备份脚本
2. 删除当前数据库
3. 在控制台中运行Add-Migration和Update-Database
4. 相应地重命名备份脚本中的表名
5. 跑过脚本

现在一切都很好.只需要弄清楚为什么加载是sooooooooooooo恼人的慢

Answer 1

当我的数据库中有对应于同一实体的重复条目时，通常会发生这种情况。

删除重复项即可使其工作。如果您有数据脚本，请检查并确认您尝试在迁移脚本中更新的实体中是否存在重复记录。