Question

这看起来应该很简单，我有以下代码

var additionalInformation=   response.AdditionalInformation.Select( async x =>  new AdditionalInformationItem
                {
                    StatementCode = x?.StatementCode?.Value,
                    LimitDateTime = x?.LimitDateTime?.Item?.Value,
                    StatementTypeCode = x?.StatementTypeCode?.Value,
                    StatementDescription = x?.StatementDescription?.Value,
                    AdditionalInformationResult = await BuildAdditionalInformationPointers(x)


                }).ToList();

我要实现的目的是让AdditionalInformation的类型为

List<AdditionalInformationItem>

，我得到的是List<Task<AdditionalInformationItem>>

有人可以帮助我正确地重新陈述我的陈述吗？

Answer 1

您需要使用Array ( [0] => Array ( [0] => Duits adres en services [1] => project:096b2fc2bc5133784c13c77ab857ae53 [2] => ) [1] => Array ( [0] => Duits adres en services [1] => project:5e920f34c4712abc4c13c77ab857ae53 [2] => ) [2] => Array ( [0] => Campagne management [1] => project:52e5cc976d1b98db4c13c77ab857ae53 [2] => ) [3] => Array ( [0] => Duits adres en services [1] => project:52e5cc976d1b98db4c13c77ab857ae53 [2] => ) [4] => Array ( [0] => Duits adres en services [1] => project:d4b09419caff744f4c13c77ab857ae53 [2] => ) )解开任务，然后使用await Task.WhenAll(additionalInformation)访问实际结果。

是这样的：

additionalInformation[0].Result

Answer 2

await Task.WhenAll将自动解包任务，并将结果交给您。

AdditionalInformationItem[] additionalInformation = await Task.WhenAll(
    response.AdditionalInformation.Select(async x => new AdditionalInformationItem
    {
        StatementCode = x?.StatementCode?.Value,
        LimitDateTime = x?.LimitDateTime?.Item?.Value,
        StatementTypeCode = x?.StatementTypeCode?.Value,
        StatementDescription = x?.StatementDescription?.Value,
        AdditionalInformationResult = await BuildAdditionalInformationPointers(x)
    });
);

Answer 3

实际上没有办法在简单的lambda表达式中执行此操作。异步Lambda表达式将始终返回Task<T>。因此，您可以快速而肮脏地在.Result上调用Task（不要这样做！除非您像Liam的answer中那样先等待），否则只需初始化一个新列表并在foreach循环中添加项目：

var additionalInformation = new List<AdditionalInformationItem>();
foreach (var x in response.AdditionalInformation)
{
    var item = new AdditionalInformationItem
        {
            StatementCode = x?.StatementCode?.Value,
            LimitDateTime = x?.LimitDateTime?.Item?.Value,
            StatementTypeCode = x?.StatementTypeCode?.Value,
            StatementDescription = x?.StatementDescription?.Value,
            AdditionalInformationResult = await BuildAdditionalInformationPointers(x)
        };

    additionalInformation.Add(item);
}

从linq语句中选择await

3 个答案: