如何获得ObjectSet< T>的实体键名？

问题描述

我已经在我的通用存储库中创建了通用 ObjectSet< T> 。

I've created a generic ObjectSet<T> in my generic repository.

我想要什么得到的是 ObjectSet< T> 的EntityKey的名称，这样我就可以在 DataContext.GetObjectByKey 。

What I would like to get is the name of the EntityKey of ObjectSet<T> so that I can use it in the DataContext.GetObjectByKey.

我已经四处搜寻并深入挖掘了，但似乎无法在任何地方找到此值 ObjectSet 类。

I've searched around and dug deep, but I can't seem to find this value anywhere in the ObjectSet class.

推荐答案

我前一阵子很不错做到这一点的方法，但没有找到。我通常最终会在其中的某个位置和其中构建一个GetEntityByKey扩展方法，污染字符串以为TryGetObjectByKey调用构建实体键。构建实体密钥的一般想法如下：

I looked a while ago for a nice way to do this and failed to find one. I generally end up building a GetEntityByKey extension method somewhere and within that, contatenating strings to build Entity Keys for TryGetObjectByKey calls. The general idea for building the entity key goes something like this:

internal class Program
{
    private static void Main(string[] args)
    {
        var dc = new AdventureWorksLT2008Entities();
        object c;
        dc.TryGetObjectByKey(GetEntityKey(dc.Customers, 23), out c);
        var customer = c as Customer;
        Console.WriteLine(customer.EmailAddress);
    }

    private static EntityKey GetEntityKey<T>(ObjectSet<T> objectSet, object keyValue) where T : class
    {
        var entitySetName = objectSet.Context.DefaultContainerName + "." + objectSet.EntitySet.Name;
        var keyPropertyName = objectSet.EntitySet.ElementType.KeyMembers[0].ToString();
        var entityKey = new EntityKey(entitySetName, new[] {new EntityKeyMember(keyPropertyName, keyValue)});
        return entityKey;
    }
}

您也许可以做类似的事情。为了简单起见，此示例假设每个EntityKey具有单个字段-对于多个值键，您需要使用 ObjectSet< T> .ElementType.KeyMembers 进行稍微复杂一些的操作，并将所有键进入EntityKey构造函数。

You may be able to do something similar. This example assumes a single field per EntityKey for simplicity - for multiple value keys you would need to do something slightly more sophisticated with ObjectSet<T>.ElementType.KeyMembers and pass all your keys into the EntityKey constructor.

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