从LinqToXYZ切换到LinqToObjects [英] Switching from LinqToXYZ to LinqToObjects

问题描述

在回答这个问题，这让我想...

In answering this question, it got me thinking...

我经常使用这种模式：

collectionofsomestuff //here it's LinqToEntities
    .Select(something=>new{something.Name,something.SomeGuid})
    .ToArray() //From here on it's LinqToObjects
    .Select(s=>new SelectListItem()
        {
            Text = s.Name, 
            Value = s.SomeGuid.ToString(), 
            Selected = false
        })

也许我把它分解了几行，但本质上，在的ToArray 点，我列举有效我的查询和存储产生的序列，这样我可以进一步与一个完整的CLR交出所有的善良处理。

Perhaps I'd split it over a couple of lines, but essentially, at the ToArray point, I'm effectively enumerating my query and storing the resulting sequence so that I can further process it with all the goodness of a full CLR to hand.

由于我有没有兴趣在任何一种中间列表操纵，我使用的ToArray 在了ToList 因为有开销少。

As I have no interest in any kind of manipulation of the intermediate list, I use ToArray over ToList as there's less overhead.

我做这一切的时候，但我不知道是否有对这类问题的一个更好的模式？

I do this all the time, but I wonder if there is a better pattern for this kind of problem?

推荐答案

有一个更好的选择： AsEnumerable

使用方法是相似的：

collectionofsomestuff //here it's LinqToEntities
    .Select(something=>new{something.Name,something.SomeGuid})
    .AsEnumerable() //From here on it's LinqToObjects
    .Select(s=>new SelectListItem()
        {
            Text = s.Name, 
            Value = s.SomeGuid.ToString(), 
            Selected = false
        })

然而，这并不强制完全复制像了ToList（）或 ToArray的（），并保留从供应商的任何延迟执行。

This, however, doesn't force a full copy to be made like ToList() or ToArray(), and preserves any deferred execution from your provider.

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