LINQ - 来自具有对象的列表的多个条件的一个布尔值答案

【问题标题】：LINQ - one bool from multiple conditions of a list with objectsLINQ - 来自具有对象的列表的多个条件的一个布尔值
【发布时间】：2021-05-31 18:08:11
【问题描述】：

我有一个包含四个对象的列表，名为任务。每个任务对象都有属性：名称（字符串）和状态（枚举）。状态可以有五种不同的条件。

我只需要一个布尔值，如果：

三个特定任务的状态为完成
某个特定任务处于非活动状态

例如，每个单独的查询：

bool isDone1 = Quests.Where(q => q.Name is "Quest1" && q.State is QuestState.Done).Any();
bool isDone2 = Quests.Where(q => q.Name is "Quest2" && q.State is QuestState.Done).Any();
bool isDone3 = Quests.Where(q => q.Name is "Quest3" && q.State is QuestState.Done).Any();
bool isInactive = Quests.Where(q => q.Name is "Quest4" && q.State is QuestState.Inactive).Any();

但是如何将它们放在一个 LINQ 查询中呢？我尝试了多种变体，但总是得到一个错误的布尔值，尽管我知道它必须是真的。例如：

        bool test= (from quest in Quests
                                   where quest.Name is "Quest1" && quest.State is QuestState.Done
                                   where quest.Name is "Quest2" && quest.State is QuestState.Done
                                   where quest.Name is "Quest3" && quest.State is QuestState.Done
                                   where quest.Name is "Quest4" && quest.State is QuestState.Inactive
                                   select quest).Any();

或者像这样：

             bool test= (from quest in Quests
                                       where quest.Name is "Quest1" && quest.State is QuestState.Done &&
                                       quest.Name is "Quest2" && quest.State is QuestState.Done &&
                                       quest.Name is "Quest3" && quest.State is QuestState.Done &&
                                       quest.Name is "Quest4" && quest.State is QuestState.Inactive
                                       select quest).Any();

还有其他一些不同的变化，但总是没有积极的结果。也许有更多 LINQ 技能的人可以帮助找到一个好的解决方案。非常感谢！

【问题讨论】：

标签： c# .net linq

【解决方案1】：

您可以创建一个list of conditions 并检查每个condition 是否满足quests 中的至少一个元素。

var conditions = new[]
{
    new {Name = "Quest 1", State = QuestState.Done},
    new {Name = "Quest 2", State = QuestState.Done},
    new {Name = "Quest 3", State = QuestState.Done},
    new {Name = "Quest 4", State = QuestState.Inactive},
};


var success= conditions.All(condition => quests.Any(quest => quest.Name == condition.Name && 
                                                    quest.State == condition.State));

【讨论】：

【解决方案2】：

如果您想让它更通用并且不将检查与特定任务名称联系起来，你可以使用这样的东西：

bool test = Quests.Count(q => q.State = QuestState.Done) == 3
         && Quests.Count(q => q.State = QuestState.Inactive) == 1

【讨论】：