访问导航属性的协会详细信息 [英] Access Association Details of NavigationProperty

问题描述

我正在创建一个基于.edmx文件的C＃T4模板来构建一些类，到目前为止这么好。我现在需要的是通过

2种实现方式：

  //获取对您感兴趣的导航属性的引用
 var navProp = GetNavigationProperty（）; 
 //加载元数据工作空间
 MetadataWorkspace metadataWorkspace = null; 
 bool allMetadataLoaded = loader.TryLoadAllMetadata（inputFile，out metadataWorkspace）; 
 
 //从存储模型获取关联类型
 var association = metadataWorkspace 
 .GetItems< AssociationType>（DataSpace.SSpace）
 .Single（a => ; a.Name == navProp.RelationshipType.Name）
 
 //然后查看引用约束
 var toColumns = String.Join（，，
 association.ReferentialConstraints .SelectMany（rc => rc.ToProperties））; 
 var fromColumns = String.Join（，，
 association.ReferentialConstraints.SelectMany（rc => rc.FromProperties））; 
  

第二种方法：

  NavigationProperty [] foreignKeys = entity.NavigationProperties 
 .Where（np => np.DeclaringType == entity&& 
（（AssociationType）np.RelationshipType）.IsForeignKey） .ToArray（）; 
 
 foreach（ForeignKeys中的NavigationProperty foreignKey）
 {
 foreach（GetSourceSchemaTypes< AssociationType>（）中的var rc 
 .Single（x => x.Name = = foreignKey.RelationshipType.Name）
 .ReferenceConstraints）
 {
 foreach（rc.ToProperties中的var tp）
 WriteLine（tp.Name）; 
 foreach（var fp in rc.FromProperties）
 WriteLine（fp.Name）; 
} 
} 
  

I'm creating a C# T4 template to scaffold some classes based on .edmx file, so far so good. What I now need though, is a way to access the name of the columns it connects in the database, through a NavigationProperty.

I realized, not long ago, that you can access this information in the .edmx visual designer, under mapping details for an specific NavigationProperty:

So basically, if in the T4 template; I already have an instance of the NavigationProperty I want... How can I get the names of the fields it connects? (WeatherOnMondays in this case)

解决方案

Answers from: EF4: Get the linked column names from NavigationProperty of an EDMX

2 ways of achieving this:

// 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));

2nd approach:

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);
   }
}

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