如何确定IEnumerable是否被评估？ [英] How to determine if an IEnumerable has been evaluated?

问题描述

我想知道我如何知道我的 IEnumerable< T> 是否已经作为内存中的列表加载（即已被评估）？

I'm wondering how I could tell if my IEnumerable<T> has been loaded as a list in memory (i.e. has been evaluated)?

我想要这个检查仅查看DateTime的日期部分，我的查询：

I want this check for checking only date portion of DateTime for my query:

private IEnumerable<AccDocumentItem> FilterDocumentItemDateFilter(IEnumerable<AccDocumentItem> accDocumentItems, FilterDocumentDate filterDocumentDate)
{   
    accDocumentItems =
    accDocumentItems.Where(x =>
            x.AccDocument.CreateDate >= filterDocumentDate.FromDocumentDate &&
            x.AccDocument.CreateDate <= filterDocumentDate.ToDocumentDate);
}

我知道在 LinqToEntity 我们可以使用 EntityFunctions.TruncateTime ，显然在 LinqToObject 中，我们可以获取日期部分 DateTime 但问题是我不知道我的 IEnumerable 是否已被执行？

I know that in LinqToEntity we can use EntityFunctions.TruncateTime and obviously in LinqToObject we can get date portion of DateTime but the problem is that I don't know if my IEnumerable has been executed or not?

编辑：
我想要这样做：

I wanted do this:

private IEnumerable<AccDocumentItem> FilterDocumentItemDateFilter(IEnumerable<AccDocumentItem> accDocumentItems, FilterDocumentDate filterDocumentDate)
{   
    if(accDocumentItems as IList<AccDocumentItem> != null)
    {
        accDocumentItems =
    accDocumentItems.Where(x =>
            x.AccDocument.CreateDate.Date >= filterDocumentDate.FromDocumentDate &&
            x.AccDocument.CreateDate.Date <= filterDocumentDate.ToDocumentDate);
    }
    else
    {
        accDocumentItems =
    accDocumentItems.Where(x =>
            EntityFunctions.TruncateTime(x.AccDocument.CreateDate) >= filterDocumentDate.FromDocumentDate &&
            EntityFunctions.TruncateTime(x.AccDocument.CreateDate) <= filterDocumentDate.ToDocumentDate);
    }
}

（谢谢Tim Schmelter;）

(Thank you Tim Schmelter ;)

推荐答案

您可以尝试使用 as operator ：

You can try to cast it with the as operator:

IList<TSource> list = source as IList<TSource>;
if (list != null)
{
    // it is a list or array
}

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