[英]How to implement many to many relationship with Entity Framework?
I have two tables with a many to many relationship. 我有两个表具有多对多关系。 I'm using Entity Framework.
我正在使用实体框架。
These are my model classes: 这些是我的模型类:
public partial class PE_Attivita
{
public PE_Attivita()
{
this.ANAG_OperatoriMedici = new HashSet<ANAG_OperatoriMedici>();
}
public int ID { get; set; }
public string Descrizione { get; set; }
public Nullable<int> IDAttivitaPare { get; set; }
public Nullable<int> CodiceCategoria { get; set; }
public string NomeAttivita { get; set; }
public virtual ICollection<ANAG_OperatoriMedici> ANAG_OperatoriMedici { get; set; }
}
public partial class ANAG_OperatoriMedici
{
public ANAG_OperatoriMedici()
{
this.PE_Attivita = new HashSet<PE_Attivita>();
}
public string CodicePersoneFisiche { get; set; }
public string Descrizione { get; set; }
public virtual ANAG_PersoneFisiche ANAG_PersoneFisiche { get; set; }
public virtual ICollection<PE_Attivita> PE_Attivita { get; set; }
}
In my database, there is a third table to implement the many to many relationship. 在我的数据库中,有第三个表来实现多对多关系。
Now I want to extract all data from this table, so I wrote this code: 现在,我想从该表中提取所有数据,因此我编写了以下代码:
activityForDoctors = from ad in db_data.PE_Attivita
.SelectMany(c => c.ANAG_OperatoriMedici)
select new ActivityDTO.activitysXDoctors
{
codiceFiscaleDottore = ad.CodicePersoneFisiche,
IdAttivita = a.ID
}
This code works but I received also duplicate data, so I thought to insert the clause Group by, and I have changed my code to this : 这段代码有效,但是我也收到了重复的数据,所以我想插入子句Group by,并将代码更改为:
activityForDoctors = from ad in db_data.PE_Attivita
.SelectMany(c => c.ANAG_OperatoriMedici).GroupBy(prop=>prop.CodicePersoneFisiche,prop=>a.ID)
select new ActivityDTO.activitysXDoctors
{
codiceFiscaleDottore = ad.CodicePersoneFisiche,
IdAttivita = a.ID
}
but I received this error from compiler: 但我从编译器收到此错误:
'System.Linq.Igrouping' does not contai a definition for 0'CodicePersoneFisiche' and no extension method 'CodicePersoneFisiche' accepting a first argument of type 'System.Linq.Igrouping' could be found (are you missing a using assembly reference?)
'System.Linq.Igrouping'没有包含0'CodicePersoneFisiche'的定义,并且找不到扩展方法'CodicePersoneFisiche'接受类型为'System.Linq.Igrouping'的第一个参数(您是否缺少使用程序集引用的信息?)
EDIT 编辑
This is the Model.edmx.diagram 这是Model.edmx.diagram
<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="3.0" xmlns:edmx="http://schemas.microsoft.com/ado/2009/11/edmx">
<!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
<edmx:Designer xmlns="http://schemas.microsoft.com/ado/2009/11/edmx">
<!-- Diagram content (shape and connector positions) -->
<edmx:Diagrams>
<Diagram DiagramId="2f7abfd0eb854868836eeaf6d91c93a4" Name="Diagram1" ZoomLevel="74">
<EntityTypeShape EntityType="ModelOmniacareData.ANAG_OperatoriMedici" Width="1.5" PointX="18.25" PointY="15.5" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.ANAG_OperatoriMediciXAssistiti" Width="1.5" PointX="20.5" PointY="18.75" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.ANAG_PersoneFisiche" Width="1.5" PointX="16" PointY="24" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.PE_Attivita" Width="1.5" PointX="13" PointY="10.5" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.PE_AttivitaXIndici" Width="1.5" PointX="15.25" PointY="11" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.PE_AttivitaXParametri" Width="1.5" PointX="18.25" PointY="7.625" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.PE_CategoriaAttivita" Width="1.5" PointX="10.75" PointY="11.625" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.PE_IndiciValutazione" Width="1.5" PointX="13" PointY="6.5" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.PE_Parametri" Width="1.5" PointX="16" PointY="19.375" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.PE_ParametriInputSchedulazioneAttivita" Width="1.5" PointX="22.75" PointY="11.25" IsExpanded="true" />
<EntityTypeShape EntityType="ModelOmniacareData.PE_Schedulazione_Attivita" Width="1.5" PointX="20.5" PointY="10.375" IsExpanded="true" />
<AssociationConnector Association="ModelOmniacareData.FK_ANAG_OperatoriMedici" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.FK_OperatoreMedicoXAssistiti_OperatoreMedico" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.FK_ParametriXValori" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.FK__MONITOR_D__IDDat__4B622666" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.FK_Attivita" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.FK_AttivitaCodiceCategoria" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.FK_AttivitaXIndiciAttivita" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.FK_AttivitaXParametriAttivita" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.FK_AttivitaXIndici" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.FK_AttivitaXParametri" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.ANAG_AssociazioniXOperatoriMedici" ManuallyRouted="false" />
<AssociationConnector Association="ModelOmniacareData.PE_AttivitaXMedico" ManuallyRouted="false" />
</Diagram>
</edmx:Diagrams>
</edmx:Designer>
</edmx:Edmx>
You will need to add a third table to describe your N to N mapping so that it becomes a N to 1 to N mapping basically. 您将需要添加第三个表来描述您的N到N映射,这样它基本上就变成了N到1到N的映射。
Right now you have created the default mapping strategy, that is two mappings of 1 to N. 现在,您已经创建了默认的映射策略,即从1到N的两个映射。
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