确定是否IQueryable< T>是否已订购 [英] Determine whether an IQueryable<T> has been ordered or not

问题描述

是否有办法知道是否已订购IQueryable<T>(使用OrderBy或OrderbyDescending)?

Is there a way to know if an IQueryable<T> has been ordered (using OrderBy or OrderbyDescending)?

所以我知道在集合中调用OrderBy还是ThenBy.

So I know whether to call OrderBy or ThenBy on the collection.

IQueryable<Contact> contacts = Database.GetContacts();

我尝试了contacts is IOrderedQueryable<Contact>，但这始终是正确的.

I tried contacts is IOrderedQueryable<Contact>, but it's always true.

编辑:我只是更改了示例，上一个示例并没有真正表明我的观点.假设GetContacts使用Entity Framework并仅返回表的所有记录.

Edit: I just changed my example, the previous one wasn't really showing my point. Assume that GetContacts uses Entity Framework and simply returns all the records of a table.

稍后，我将几个功能应用于contacts，我不知道这些功能的作用.他们可以对IQueryable<Contact>进行排序或过滤.

Later on, I apply several functions to contacts, I have no knowledge of what those functions do. They can sort or filter the IQueryable<Contact>.

当我拿回收藏集时，我需要再次对其进行排序.为此，我需要知道是否需要调用OrderBy或ThenBy.因此，如果已对整个集合进行排序，我就不会对其重新排序.

When I get the collection back, I need to sort it once more. To do so, I need to know whether I need to call OrderBy, or ThenBy. So I don't reorder the whole collection if it has already been sorted.

推荐答案

简短的回答是否"，Queryable类不维护标志，也不维护集合是否已排序，也不可以使用什么方法执行此类排序.

Short answer is no, the Queryable class doesn't maintain a flag or whether the collection is sorted nor what method may have been used to perform such a sort.

http://msdn.microsoft.com/zh-我们/library/system.linq.queryable.aspx

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