这可能很简单,但我无法正确理解。 这是我的接线 - 事件与规则有多对多的关系。事件可能有也可能没有规则。规则将有其自己的细节。底线,我需要这样的对象:带外连接的Linq查询不会返回预期的结果
对象
- 事件
- 规则(空)
- 映射表(空)
所以,我硬编码这些关系为以下
Dim eventList As new List(Of [Event])
eventList.Add(new [Event]() With {.EventId = 1, .ClassId = 1, .TypeId = 1, .EventSequence = 2}) ' this is event without rules
eventList.Add(new [Event]() With {.EventId = 2, .ClassId = 1, .TypeId = 1, .EventSequence = 1})
eventList.Add(new [Event]() With {.EventId = 3, .ClassId = 1, .TypeId = 1, .EventSequence = 3})
Dim ruleEventList As New List(Of RuleEvent)
ruleEventList.Add(new RuleEvent() With {.Id = 1, .EventId = 2, .RuleId = 1})
ruleEventList.Add(new RuleEvent() With {.Id = 2, .EventId = 3, .RuleId = 1})
Dim ruleList As New List(Of Rule)
ruleList.Add(new Rule() With {.Id = 1, .EntityId = 1, .SearchId = 1})
Dim ruleDetailList As New List(Of RuleDetail)
ruleDetailList.Add(new RuleDetail() With {.Id = 1, .RuleId = 1, .Value = "aaa"})
ruleDetailList.Add(new RuleDetail() With {.Id = 2, .RuleId = 1, .Value = "bbb"})
这似乎是正确的,因为2/3正常工作。但这里是LINQ
Dim eventRuleDetailList = _
From ev In eventList
From re In ruleEventList.Where(Function(r) r.EventId = ev.EventId).DefaultIfEmpty()
From rule In ruleList.Where(Function(r) re IsNot Nothing AndAlso r.Id = re.RuleId).DefaultIfEmpty()
From det In ruleDetailList.Where(Function(r) rule IsNot Nothing AndAlso r.RuleId = rule.Id).DefaultIfEmpty()
Group ev, rule, det By ev.EventId, ev.ClassId, ev.TypeId, ev.EventSequence
Into g = Group
Order By ClassId, TypeId, EventSequence
Select New With
{
.EventId = EventId,
.Event = g.First().ev,
.Rule = g.First().rule,
.Details = g.Select(Function(itm) itm.det) '<-- This is my glitch
}
结果似乎几乎是正确的,但有一个问题。我似乎无法得到 “详细信息” 的权利
For Each erd In eventRuleDetailList
Console.WriteLine("Event Id: {0}; Event Seq: {1}; Rule Id: {2}; Details: {3}",
erd.EventId,
erd.Event.EventSequence,
If (erd.Rule Is Nothing, "No Rules", erd.Rule.Id),
If (erd.Details Is Nothing, "No Details", "Yes Details")
)
Next
输出:
事件ID:2;事件序号:1;规则Id:1;详情:是详细信息
事件Id:1;事件序号:2;规则ID:无规则;详情:是详细信息
事件Id:3;事件序号:3;规则Id:1; Mapped Details:是详细信息
这是问题所在。我做错了什么,因为Event Id: 1
应该说“没有详细信息”。它具有“无规则”
感谢
不好。 'g.First().det'是单一的。我需要很多。 –
在你的问题中,你将它视为一个布尔值。如果你需要一种不同的方式,你应该清楚你的问题描述。 如果你需要它作为一个列表,然后找到一种不同的方式来确定它的存在。 –
我修好了 - 检查答案。谢谢 –