我有一張世界事件表。每個世界事件都有一個在某個國家/地區(qū)發(fā)生的與該世界事件相關(guān)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",}, };現(xiàn)在 - 我怎樣才能獲得在英國進行演示的 WorldEvents 列表。而且 - 在我感興趣的列表中，WorldEvents 應(yīng)僅包含有關(guān)英國演示文稿的信息。換句話說，我需要這個結(jié)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貢獻1884條經(jīng)驗 獲得超4個贊
如果我明白你想要什么。有很多方法可以做到這一點，但是您可以先進行過濾，然后WorldEvents使用過濾后的列表重新創(chuàng)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在評論中指出的那樣，您可以在事后過濾
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：因為這不是投影（選擇）每個Presentation，所以您對 aPresentation中所做的任何更改都result將反映在原始數(shù)據(jù)中。如果您不希望這樣，則需要重新創(chuàng)建每個Presentation
吃雞游戲
TA貢獻1829條經(jīng)驗 獲得超7個贊
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貢獻1853條經(jīng)驗 獲得超18個贊
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貢獻1797條經(jīng)驗 獲得超4個贊
不確定我的理解是否正確，我猜您的 WorldEvent 和演示表之間存在一對多的關(guān)系。因此，如果您想通過使用 EntityFramework 獲取在英國發(fā)生的所有 WorldEvents 及其相關(guān)演示，您可以嘗試以下操作：
worldEventContext
.Include(PresentationContext)
.Select(
w => new
{
w.ID,
w.Name,
PresentationList = w.PresentationContext.Where(p => p.Country == "UK")
})
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