C# 将 List<t> 转换或强制转换为 EntityCollection<T>
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原文地址: http://stackoverflow.com/questions/2364676/
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convert or cast a List<t> to EntityCollection<T>
提问by alice7
How would you to convert or cast a List<T>to EntityCollection<T>?
您将如何将 a 转换或强制转换List<T>为EntityCollection<T>？
Sometimes this occurs when trying to create 'from scratch' a collection of child objects (e.g. from a web form)
有时在尝试“从头开始”创建子对象集合（例如，从 Web 表单）时会发生这种情况
Cannot implicitly convert type 'System.Collections.Generic.List' to 'System.Data.Objects.DataClasses.EntityCollection'
采纳答案by Johannes Rudolph
I assume you are talking about List<T>and EntityCollection<T>which is used by the Entity Framework. Since the latter has a completely different purpose (it's responsible for change tracking) and does not inherit List<T>, there's no direct cast.
我假设你正在谈论List<T>和EntityCollection<T>所使用实体框架。由于后者具有完全不同的目的（它负责更改跟踪）并且不继承List<T>，因此没有直接强制转换。
You can create a new EntityCollection<T>and add all the List members.
您可以创建一个新的EntityCollection<T>并添加所有 List 成员。
var entityCollection = new EntityCollection<TEntity>();
foreach (var item m in list)
{
entityCollection.Add(m);
}
Unfortunately EntityCollection<T>neither supports an Assign operation as does EntitySet used by Linq2Sql nor an overloaded constructor so that's where you're left with what I stated above.
不幸的是，它EntityCollection<T>既不支持 Linq2Sql 使用的 EntitySet 操作，也不支持重载的构造函数，所以这就是我上面所说的。
回答by David Sherret
In one line:
在一行中：
list.ForEach(entityCollection.Add);
Extension method:
扩展方法：
public static EntityCollection<T> ToEntityCollection<T>(this List<T> list) where T : class
{
EntityCollection<T> entityCollection = new EntityCollection<T>();
list.ForEach(entityCollection.Add);
return entityCollection;
}
Use:
用：
EntityCollection<ClassName> entityCollection = list.ToEntityCollection();
回答by Tim Partridge
No LINQ required. Just call the constructor
不需要 LINQ。只需调用构造函数
List<Entity> myList = new List<Entity>();
EntityCollection myCollection = new EntityCollection(myList);
