Templates EF4：从EDMX的NavigationProperty获取链接的列名

我使用来自EDMX文件的T4模板生成POCO（假设它们是MyEntityObject的子类）

我有3个实体，例如：

• MyTable1（主键：MyTable1ID）
• MyTable2（主键：MyTable2ID）
• MyTable3（主键：MyTable3ID）

这些实体具有以下关系：

MyTable1.MyTable1ID MyTable2.MyTable1ID（MyTable1ID是 MyTable1的外键

MyTable2.MyTable2ID MyTable3.MyTable2ID（MyTable2ID是 MyTable2的外键

或者从另一个角度来看：

---

MyTable1不确定是否要使用列生成代码，但这可能部分有助于回答您的问题（如何提取两个实体之间链接的列名？）

NavigationProperty[]foreignKeys=entity.NavigationProperties
.其中（np=>np.DeclaringType==实体&&
（（AssociationType）np.RelationshipType）.IsForeignKey.ToArray（）；
foreach（foreignKey中的NavigationProperty foreignKey）
{
foreach（GetSourceSchemaTypes（）中的var rc）
.Single（x=>x.Name==foreignKey.RelationshipType.Name）
.参考约束）
{
foreach（rc.TopProperty中的var tp）
WriteLine（总称）；
foreach（rc.FromProperties中的变量fp）
WriteLine（fp.Name）；
}
}

如果外键列在概念模型中作为属性公开，则第一个答案有效。此外，GetSourceSchemaTypes（）方法仅在EF中包含的一些文本模板中可用，因此了解此方法的功能很有帮助

如果希望始终知道列名，则需要按如下方式从存储模型加载AssociationType：

// Obtain a reference to the navigation property you are interested in
var navProp = GetNavigationProperty();

// Load the metadata workspace
MetadataWorkspace metadataWorkspace = null;
bool allMetadataLoaded =loader.TryLoadAllMetadata(inputFile, out metadataWorkspace);

// Get the association type from the storage model
var association = metadataWorkspace
    .GetItems<AssociationType>(DataSpace.SSpace)
    .Single(a => a.Name == navProp.RelationshipType.Name)

// Then look at the referential constraints
var toColumns = String.Join(",", 
    association.ReferentialConstraints.SelectMany(rc => rc.ToProperties));
var fromColumns = String.Join(",", 
    association.ReferentialConstraints.SelectMany(rc => rc.FromProperties));

//获取对您感兴趣的导航属性的引用
var navProp=GetNavigationProperty（）；
//加载元数据工作区
MetadataWorkspace MetadataWorkspace=null；
bool allMetadataLoaded=loader.TryLoadAllMetadata（inputFile，OutMetadataWorkspace）；
//从存储模型中获取关联类型
var关联=metadataWorkspace
.GetItems（DataSpace.SSpace）
.Single（a=>a.Name==navProp.RelationshipType.Name）
//然后看看引用约束
var toColumns=String.Join（“，”，
SelectMany（rc=>rc.ToProperties））；
var fromColumns=String.Join（“，”，
SelectMany（rc=>rc.FromProperties））；

---

在本例中，loader是在EF.Utility.CS.ttinclude中定义的MetadataLoader，inputFile是指定.edmx文件名的标准字符串变量。这些应该已经在您的文本模板中声明。

此代码在my Visual Studio 2012上运行良好

<#@ template language="C#" debug="true" hostspecific="true"#>
<#@ include file="EF.Utility.CS.ttinclude"#>
<#
string inputFile = @"DomainModel.edmx";

MetadataLoader loader = new MetadataLoader(this);

EdmItemCollection ItemCollection = loader.CreateEdmItemCollection(inputFile);

foreach (EntityType entity in ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name))
{
    foreach (NavigationProperty navProperty in entity.NavigationProperties)
    {
        AssociationType association = ItemCollection.GetItems<AssociationType>().Single(a => a.Name == navProperty.RelationshipType.Name);
        string fromEntity = association.ReferentialConstraints[0].FromRole.Name;
        string fromEntityField = association.ReferentialConstraints[0].FromProperties[0].Name;
        string toEntity = association.ReferentialConstraints[0].ToRole.Name;
        string toEntityField = association.ReferentialConstraints[0].ToProperties[0].Name;
    }
}

#>

e、 （姓名）
{
foreach（实体中的NavigationProperty navProperty.NavigationProperties）
{
AssociationType association=ItemCollection.GetItems（）.Single（a=>a.Name==navProperty.RelationshipType.Name）；
string fromEntity=association.ReferentialConstraints[0]。FromRole.Name；
字符串fromEntityField=association.ReferentialConstraints[0]。FromProperties[0]。名称；
string toEntity=association.ReferentialConstraints[0].ToRole.Name；
string toEntityField=association.ReferentialConstraints[0]。TopProperties[0]。名称；
}
}
#>

string myTable1Column;
string myTable2Column;
GetLinkedColumns(myTable1, myTable2, out myTable1Column, out myTable2Column);

myTable1Column = "MyTable1ID";
myTable2Column = "MyTable2ID";

NavigationProperty[] foreignKeys = entity.NavigationProperties
  .Where(np => np.DeclaringType == entity &&
          ((AssociationType)np.RelationshipType).IsForeignKey).ToArray();

foreach (NavigationProperty foreignKey in foreignKeys)
{
   foreach(var rc in GetSourceSchemaTypes<AssociationType>()
       .Single(x => x.Name == foreignKey.RelationshipType.Name)
       .ReferentialConstraints)
   {
       foreach(var tp in rc.ToProperties)
           WriteLine(tp.Name);
       foreach(var fp in rc.FromProperties)
           WriteLine(fp.Name);
   }
}

// Obtain a reference to the navigation property you are interested in
var navProp = GetNavigationProperty();

// Load the metadata workspace
MetadataWorkspace metadataWorkspace = null;
bool allMetadataLoaded =loader.TryLoadAllMetadata(inputFile, out metadataWorkspace);

// Get the association type from the storage model
var association = metadataWorkspace
    .GetItems<AssociationType>(DataSpace.SSpace)
    .Single(a => a.Name == navProp.RelationshipType.Name)

// Then look at the referential constraints
var toColumns = String.Join(",", 
    association.ReferentialConstraints.SelectMany(rc => rc.ToProperties));
var fromColumns = String.Join(",", 
    association.ReferentialConstraints.SelectMany(rc => rc.FromProperties));

<#@ template language="C#" debug="true" hostspecific="true"#>
<#@ include file="EF.Utility.CS.ttinclude"#>
<#
string inputFile = @"DomainModel.edmx";

MetadataLoader loader = new MetadataLoader(this);

EdmItemCollection ItemCollection = loader.CreateEdmItemCollection(inputFile);

foreach (EntityType entity in ItemCollection.GetItems<EntityType>().OrderBy(e => e.Name))
{
    foreach (NavigationProperty navProperty in entity.NavigationProperties)
    {
        AssociationType association = ItemCollection.GetItems<AssociationType>().Single(a => a.Name == navProperty.RelationshipType.Name);
        string fromEntity = association.ReferentialConstraints[0].FromRole.Name;
        string fromEntityField = association.ReferentialConstraints[0].FromProperties[0].Name;
        string toEntity = association.ReferentialConstraints[0].ToRole.Name;
        string toEntityField = association.ReferentialConstraints[0].ToProperties[0].Name;
    }
}

#>