如何使用 Linq to object 构建层次结构? [英] How to build a hierarchy with use Linq to object?
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问题描述
我有一个数据结构列表:
I have a list of data structures:
public List<Personal> Personals()
{
return new List<Personal>
{
new Personal
{
Id = 0,
Name = "Name 0"
},
new Personal
{
Id = 1,
Name = "Name 1",
ParentId = 0
},
new Personal
{
Id = 2,
Name = "Name 2",
ParentId = 0
},
new Personal
{
Id = 3,
Name = "Name 3",
ParentId = 0
},
new Personal
{
Id = 4,
Name = "Name 4",
ParentId = 1
},
new Personal
{
Id = 5,
Name = "Name 5",
ParentId = 1
},
new Personal
{
Id = 6,
Name = "Name 6",
ParentId = 2
},
new Personal
{
Id = 7,
Name = "Name 7",
ParentId = 2
},
new Personal
{
Id = 8,
Name = "Name 8",
ParentId = 4
},
new Personal
{
Id = 9,
Name = "Name 9",
ParentId = 4
},
};
}
我想建一棵树:
public List<Tree> Trees()
{
return new List<Tree>
{
new Tree
{
Id = 0,
Name = "Name 0",
List = new List<Tree>
{
new Tree
{
Id = 1,
Name = "Name 1",
List = new List<Tree>
{
new Tree
{
Id = 4,
Name = "Name 4"
},
new Tree
{
Id = 5,
Name = "Name 5"
}
}
}
}
}
};
}
你如何用 LinQ 构建一棵树来反对?我必须使用,但它不能完全正常工作,请参见下文:
How do you build a tree with LinQ to object? I have to use but it doesn't work exactly, see below:
public List<Tree> GetTree(List<Personal> list)
{
var listFormat = list.Select(x => new Tree
{
Id = x.Id,
Name = x.Name,
ParentId = x.ParentId
}).ToList();
var lookup = listFormat.ToLookup(f => f.ParentId);
foreach (var tree in listFormat)
{
tree.List = lookup[tree.Id].ToList();
}
return listFormat;
}
推荐答案
你应该使用递归:
public void SomeMethod() {
// here you get your `list`
var tree = GetTree(list, 0);
}
public List<Tree> GetTree(List<Personal> list, int parent) {
return list.Where(x => x.ParentId == parent).Select(x => new Tree {
Id = x.Id,
Name = x.Name,
List = GetTree(list, x.Id)
}).ToList();
}
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