我有一张世界事件表。每个世界事件都有一个在某个国家/地区发生的与该世界事件相关的演示列表public class WorldEvent{ public int ID { get; set; } public string Name { get; set; } public List<Presentation> PresentationList { get; set; }}public class Presentation{ public int ID { get; set; } public string Name { get; set; } public string Country { get; set; }}public class WorldEventService{ public List<WorldEvent> GetWorldEvents() { List<WorldEvent> worldEventList = new List<WorldEvent>(); List<Presentation> presentationList = new List<Presentation>(); // Create list of Presentations for WorldEvent_1 presentationList = new List<Presentation>() { new Presentation() { ID = 1, Name = "Presentation_1", Country = "Germany",}, new Presentation() { ID = 2, Name = "Presentation_2", Country = "UK",}, new Presentation() { ID = 3, Name = "Presentation_3", Country = "UK",}, }; // Add WorldEvent_1 to the list of WorldEvents worldEventList.Add(new WorldEvent() { ID = 1, Name = "WorldEvent_1", PresentationList = presentationList, }); // Create list of Presentations for WorldEvent_2 presentationList = new List<Presentation>() { new Presentation() { ID = 4, Name = "Presentation_4", Country = "USA",}, new Presentation() { ID = 5, Name = "Presentation_5", Country = "UK",}, new Presentation() { ID = 6, Name = "Presentation_6", Country = "Japan",}, };现在 - 我怎样才能获得在英国进行演示的 WorldEvents 列表。而且 - 在我感兴趣的列表中，WorldEvents 应仅包含有关英国演示文稿的信息。换句话说，我需要这个结果：世界事件_1（演示文稿_2、演示文稿_3）世界事件_2（演示_5）
4 回答
慕村9548890
TA贡献1884条经验 获得超4个赞
如果我明白你想要什么。有很多方法可以做到这一点，但是您可以先进行过滤，然后WorldEvents使用过滤后的列表重新创建Presentation
var country = "UK";
var result = worldEventList.Where(x => x.PresentationList.Any(y => y.Country == country))
.Select(x => new WorldEvent()
{
ID = x.ID,
Name = x.Name,
PresentationList = x.PresentationList
.Where(y => y.Country == country)
.ToList()
}).ToList();
或者正如Gert Arnold在评论中指出的那样，您可以在事后过滤
var result = worldEventList.Select(x => new WorldEvent()
{
ID = x.ID,
Name = x.Name,
PresentationList = x.PresentationList
.Where(y => y.Country == country).ToList()
}).Where(x => x.PresentationList.Any())
.ToList();
注意：因为这不是投影（选择）每个Presentation，所以您对 aPresentation中所做的任何更改都result将反映在原始数据中。如果您不希望这样，则需要重新创建每个Presentation
吃鸡游戏
TA贡献1829条经验 获得超7个赞
var worldEvent = new WorldEventService.GetWorldEvents();
var filter = "";//userInput
var filteredResult = worldEvent.Select(r => new WorldEvent
{
PresentationList = r.PresentationList.Where(c => c.Country == filter).ToList(),
ID = r.Id,
Name = r.Name
}).ToList();
慕容森
TA贡献1853条经验 获得超18个赞
public static List<WorldEvent> Filter(string Country, List<WorldEvent> events) {
var evs = from ev in events.Where(x => x.PresentationList.Any(y => y.Country == Country))
let targetPres = from pres in ev.PresentationList
where pres.Country == Country
select pres
select new WorldEvent {
ID = ev.ID,
Name = ev.Name,
PresentationList = targetPres.ToList()
};
return evs.ToList();
}
繁星coding
TA贡献1797条经验 获得超4个赞
不确定我的理解是否正确，我猜您的 WorldEvent 和演示表之间存在一对多的关系。因此，如果您想通过使用 EntityFramework 获取在英国发生的所有 WorldEvents 及其相关演示，您可以尝试以下操作：
worldEventContext
.Include(PresentationContext)
.Select(
w => new
{
w.ID,
w.Name,
PresentationList = w.PresentationContext.Where(p => p.Country == "UK")
})
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