EF代码优先：序列包含多个匹配元素 [英] EF code-first: Sequence contains more than one matching element

问题描述

我正在使用EF6代码，并且有一个用户类，需要有到其他用户的传入和传出连接。连接也有属性，所以我也有一个连接类。

  public class User 
 {
 public int ID {get;组; $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ 
 
 //删除此处的其他属性以保持简单
 
 [InverseProperty（SourceUser OutgoingConnections {get;组; } 
 
 [InverseProperty（DestUser）] 
 public virtual ICollection< Connection> IncomingConnections {get;组; 
} 
 
 public class Connection 
 {
 public int ID {get;组; 
 
 //其他属性被删除，以保持简单
 
 [InverseProperty（OutgoingConnections）] 
 public User SourceUser {get;组; } 
 
 [InverseProperty（IncomingConnections）] 
 public User DestUser {get;组; } 
} 
  

更新数据库时出现以下错误。最初我没有 InverseProperty 属性，所以我可以理解为什么EF不知道该怎么做。文档听起来像这些属性是我想要的 - 但它仍然不起作用。也许我误会了，但是，我想最终得到一个用户表，而$ code>连接表，其中连接表具有 ID ， SourceUserID ， DestUserID （显然与FK约束）。

任何想法？

指定-Verbose标志，以查看正在应用的SQL语句
到目标数据库。应用明确的迁移：
[201411192045091_InitialCreate]。应用显式迁移：
201411192045091_InitialCreate。 System.InvalidOperationException：
序列包含
上的多个匹配元素System.Linq.Enumerable.SingleOrDefault [TSource]（IEnumerable 1来源，
Func 2谓词）在
System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer。<> c__DisplayClass250.b__247（<> f__AnonymousType2b 2
< h__TransparentIdentifier242 ）at
System.Linq.Enumerable.WhereSelectEnumerableIterator 2.MoveNext（）

在System.Linq.Enumerable.WhereSelectEnumerableIterator 2.MoveNext（ ）

在System.Collections.Generic.List 1..ctor（IEnumerable 1集合）

在System.Linq。在
System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.Diff（ModelMetadata
source，ModelMetadata target，Lazy <$）中的Enumerable.ToList [TSource]（IEnumerable 1源） c $ c> 1 modifyCommandTreeGenerator，
MigrationSqlGenerator migrationSqlGenerator，String
sourceModelVersion，String ta rgetModelVersion）
System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.Diff（XDocument
sourceModel，XDocument targetModel，Lazy 1
modifyCommandTreeGenerator，MigrationSqlGenerator
migrationSqlGenerator，String sourceModelVersion，String
targetModelVersion）
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 。升级（IEnumerable 1
pendingMigrations，String targetMigrationId，String lastMigrationId）

在System.Data.Entity.Migrations.DbMigrator.UpdateInternal（String
targetMigration ）at
System.Data.Entity.Migrations.DbMigrator。<> c__DisplayClassc.b__b（）
at
System.Da ta.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（）
在System.AppDomain.DoCallBack（CrossAppDomainDelegate
callBackDelegate）在
System.AppDomain.DoCallBack（CrossAppDomainDelegate callBackDelegate）

在System.Data.Entity.Migrations.Design.ToolingFacade.Run（BaseRunner
runner）at
System.Data.Entity.Migrations.Design.ToolingFacade.Update（String
targetMigration，Boolean force）在
System.Data.Entity.Migrations.UpdateDatabaseCommand。<> c__DisplayClass2。< .ctor> b__0（）
at
System.Data.Entity.Migrations.MigrationsDomainCommand.Execute（Action
命令）序列包含多个匹配元素

解决方案

对不起，如果使用InverseProperties是一个要求，但如果您有灵活性，可以以不同的方式进行关系。

  public class User 
 {
 public int ID {get;组; } 
 
 [ForeignKey（ID）] 
 public virtual ICollection< Connection> OutgoingConnections {get;组; } 
 
 [ForeignKey（ID）] 
 public virtual ICollection< Connection> IncomingConnections {get;组; 
} 
 
 public class Connection 
 {
 public int ID {get;组; } 
 
 public int SourcerId {get; set;} 
 
 public int DestUserId {get; set;} 
 
 [ForeignKey（SourcerId ] 
 public User SourceUser {get;组; } 
 
 [ForeignKey（DestUserId）] 
 public User DestUser {get;组; } 
} 
  

然后你需要添加配置。在我的情况下，测试这个我在上下文中保护覆盖void OnModelCreating（DbModelBuilder modelBuilder）。

  modelBuilder.Entity<使用者>（）的hasMany（X => x.IncomingConnections）.WithRequired（X => x.SourceUser）.WillCascadeOnDelete（假）; 
 modelBuilder.Entity< User>（）。HasMany（x => x.OutgoingConnections）.WithRequired（x => x.DestUser）.WillCascadeOnDelete（false）; 
  

I'm using EF6 code-first, and have a User class that needs to have incoming and outgoing connections to other users. A connection also has properties, so I also have a Connections class.

public class User
{
    public int ID { get; set; }

    // Other properties removed here to keep it simple

    [InverseProperty("SourceUser")]
    public virtual ICollection<Connection> OutgoingConnections { get; set; }

    [InverseProperty("DestUser")]
    public virtual ICollection<Connection> IncomingConnections { get; set; }
}

public class Connection
{
    public int ID { get; set; }

    // Other properties removed here to keep it simple

    [InverseProperty("OutgoingConnections")]
    public User SourceUser { get; set; }

    [InverseProperty("IncomingConnections")]
    public User DestUser { get; set; }
}

I'm getting the following error when updating my database. Initially I didn't have the InverseProperty attributes, so I can understand why EF didn't know what to do in that case. The documentation sounds like these attributes are what I want though - but it's still not working. Perhaps I'm misunderstanding it though.

I want to end up with a Users table, and a Connections table where the Connections table has ID, SourceUserID, DestUserID (obviously with FK constraints).

Any ideas?

Specify the '-Verbose' flag to view the SQL statements being applied to the target database. Applying explicit migrations: [201411192045091_InitialCreate]. Applying explicit migration: 201411192045091_InitialCreate. System.InvalidOperationException: Sequence contains more than one matching element at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable1 source, Func2 predicate) at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.<>c__DisplayClass250.b__247(<>f__AnonymousType2b2 <>h__TransparentIdentifier242) at System.Linq.Enumerable.WhereSelectEnumerableIterator2.MoveNext()
at System.Linq.Enumerable.WhereSelectEnumerableIterator2.MoveNext()
at System.Collections.Generic.List1..ctor(IEnumerable1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable1 source) at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.Diff(ModelMetadata source, ModelMetadata target, Lazy1 modificationCommandTreeGenerator, MigrationSqlGenerator migrationSqlGenerator, String sourceModelVersion, String targetModelVersion) at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.Diff(XDocument sourceModel, XDocument targetModel, Lazy1 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(IEnumerable1 pendingMigrations, String targetMigrationId, String lastMigrationId)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable1 pendingMigrations, String targetMigrationId, String lastMigrationId)
at System.Data.Entity.Migrations.DbMigrator.UpdateInternal(String targetMigration) at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClassc.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 matching element

解决方案

Sorry if using InverseProperties is a requirement but the relationships can be done this way if you have the flexibility to wire them up differently.

public class User
{
    public int ID { get; set; }

    [ForeignKey("ID")]
    public virtual ICollection<Connection> OutgoingConnections { get; set; }

    [ForeignKey("ID")]
    public virtual ICollection<Connection> IncomingConnections { get; set; }
}

public class Connection
{
    public int ID { get; set; }

    public int SourcerId {get;set;}

    public int DestUserId {get;set;}

    [ForeignKey("SourcerId")]
    public User SourceUser { get; set; }

     [ForeignKey("DestUserId")]
    public User DestUser { get; set; }
}

then you need to add configurations. In my case to test this I did it in protected override void OnModelCreating(DbModelBuilder modelBuilder) in the context.

    modelBuilder.Entity<User>().HasMany(x=>x.IncomingConnections).WithRequired(x=>x.SourceUser).WillCascadeOnDelete(false);
    modelBuilder.Entity<User>().HasMany(x => x.OutgoingConnections).WithRequired(x => x.DestUser).WillCascadeOnDelete(false);

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