目录

一、需求：

二、实现代码

三、递归代码

四、思考

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一、需求：

给小明一家生成族谱树

二、实现代码

using Newtonsoft.Json;class Person
{public int Id { get; set; }public int? ParentID { get; set; }public string Name { get; set; }
}class TreeDto : Person
{[JsonProperty(Order =99)]public List<TreeDto> Children = new List<TreeDto>();
}class Program
{static List<Person> PersonList = new List<Person>(){new Person(){ Id=1,ParentID=null,Name="小明曾祖父",},new Person(){ Id=2,ParentID=1,Name="小明爷爷",},new Person(){ Id=3,ParentID=1,Name="小明二爷爷",},new Person(){ Id=4,ParentID=1,Name="小明三爷爷",},new Person(){ Id=5,ParentID=2,Name="小明爸爸",},new Person(){ Id=6,ParentID=2,Name="小明叔叔",},new Person(){ Id=7,ParentID=5,Name="小明本人",},new Person(){ Id=8,ParentID=5,Name="小明妹妹",},new Person(){ Id=9,ParentID=7,Name="小明儿子",}};static void Main(){TreeDto tree = BuildTree(null);//传入列表根节点【小明曾祖父】，开始递归var result = JsonConvert.SerializeObject(tree);//实体=>JSON打印Console.WriteLine(result);}static TreeDto BuildTree(int? parentId){var children = PersonList.Where(p => p.ParentID == parentId).Select(p => new TreeDto{Id = p.Id,ParentID = p.ParentID,Name = p.Name,Children = BuildTree(p.Id).Children}).ToList();return new TreeDto{Id = parentId ?? 0, //父级IdParentID = null,Name = "族谱",Children = children};}
}

【效果】

{"Id": 0,"ParentID": null,"Name": "族谱","Children": [{"Id": 1,"ParentID": null,"Name": "小明曾祖父","Children": [{"Id": 2,"ParentID": 1,"Name": "小明爷爷","Children": [{"Id": 5,"ParentID": 2,"Name": "小明爸爸","Children": [{"Id": 7,"ParentID": 5,"Name": "小明本人","Children": [{"Id": 9,"ParentID": 7,"Name": "小明儿子","Children": []}]},{"Id": 8,"ParentID": 5,"Name": "小明妹妹","Children": []}]},{"Id": 6,"ParentID": 2,"Name": "小明叔叔","Children": []}]},{"Id": 3,"ParentID": 1,"Name": "小明二爷爷","Children": []},{"Id": 4,"ParentID": 1,"Name": "小明三爷爷","Children": []}]}]
}

三、递归代码

static TreeDto BuildTree(int? parentId)
{var children = PersonList.Where(p => p.ParentID == parentId).Select(p => new TreeDto{Id = p.Id,ParentID = p.ParentID,Name = p.Name,Children = BuildTree(p.Id).Children}).ToList();return new TreeDto{Id = parentId ?? 0, //父级IdParentID = null,Name = "族谱",Children = children};
}

四、思考

1.设定序列化的字段顺序，例如将Children这个字段放最后面

 2.递归的写法注释

3.如果根节点不想设为族谱，如何获取从曾祖父开始的递归树 

将

var result = JsonConvert.SerializeObject(tree);//族谱开始

改为

var result = JsonConvert.SerializeObject(tree.Children.FirstOrDefault());//曾祖父开始

4.如果想在族谱上加一个根节点，如何操作

【代码】

 TreeDto tree = BuildTree(null);//获取递归结果var result = new TreeDto{Id = 1000,Name = "新增根节点",Children = new List<TreeDto>() { tree }};

【效果】