LINQ:如何通过这样的元素进行分组可以被添加到很多组中 [英] LINQ: how to group by so element can be added to many groups
问题描述
我有3种类型:参数
,设施
和位置
。 参数
有一个设施
和设施
与多对多 - Location 。所以,如果我们建立一个连接,我们可以得到这样一个表:
参数ID FacilityId LocationId
1 1 1
1 1 2
2 2 1
2 2 3
现在我想按位置对参数进行分组,以便我得到一个Dictionary>,如下所示:
LocationId参数
1 1,2
2 1
3 2
我不能做直接GroupBy,因为我不知道如何写一个keySelector。我也尝试过这样的SelectMany:
parametersList.SelectMany(t => t.Facility.Locations).GroupBy(t = > t)
.ToDictionary(t => t.Key,t => t.Select(val => val))
但它无法形成我的字典..
更新:
这是我的Facility(简化)的样子:
public class Facility
{
public int Id {get;组; }
public ICollection< Location>地点{get;组; }
}
这里是位置:
public class Location
{
public int Id {get;组; }
public ICollection< Facility>设施{get;组; }
}
我会很乐意为您提供任何帮助!
此查询返回您想要的结果:
parametersListList
.SelectMany(_ => _.Facility.Locations)
.GroupBy(_ => _)
.ToDictionary(
_ => _.Key,
_ => _.SelectMany(l => l.Facilities).SelectMany(f => f.Parameters).Distinct()。ToArray());
更新
<您可以使用 parametersList
或存储参数:
parametersListList
.SelectMany(_ => _.Facility.Locations)
.GroupBy(_ => _)
.ToDictionary(
_ => _.Key,
_ => _.SelectMany(l => l.Facilities).Select(f => parametersList.Single(p => p.Facility == f))Distinct()。ToArray ));
I have 3 types: Parameter
, Facility
and Location
. Parameter
has one Facility
and Facility
is related many-to-many with Location
. So, if we make a join, we can get such a table:
ParamId FacilityId LocationId
1 1 1
1 1 2
2 2 1
2 2 3
Now i want to group my parameters by locations so that i get a Dictionary>, like this:
LocationId Parameters
1 1,2
2 1
3 2
I can't do a straight GroupBy because i don't know how to write a keySelector. I Also tried SelectMany like this:
parametersList.SelectMany(t=>t.Facility.Locations).GroupBy(t =>t)
.ToDictionary(t=>t.Key, t=>t.Select(val=>val))
but it cannot form me my Dictionary..
Update: Here is how my Facility (simplified) looks like:
public class Facility
{
public int Id { get; set; }
public ICollection<Location> Locations { get; set; }
}
and here is Location:
public class Location
{
public int Id { get; set; }
public ICollection<Facility> Facilities { get; set; }
}
I'll be gratefull for any help!
This query return that you want:
parametersList
.SelectMany(_ => _.Facility.Locations)
.GroupBy(_ => _)
.ToDictionary(
_ => _.Key,
_ => _.SelectMany(l => l.Facilities).SelectMany(f => f.Parameters).Distinct().ToArray());
UPDATE
You can use parametersList
or store of parameters for it:
parametersList
.SelectMany(_ => _.Facility.Locations)
.GroupBy(_ => _)
.ToDictionary(
_ => _.Key,
_ => _.SelectMany(l => l.Facilities).Select(f => parametersList.Single(p => p.Facility == f)).Distinct().ToArray());
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