C# 树形结构tree拼接

实体类:

public class Project
{
    public Project()
    {
        children = new List<Project>();
    }
    public int id { get; set; }
    public int parentId { get; set; }
    public string name { get; set; }
    public List<Project> children { get; set; }
}

• 所有表结构数据

id	parentId	name
1	-1	name1
2	1	name2
3	1	name3
4	2	name4

• 查询所有数据

  public List<Project> GetProjectTree()
  {
  List<Project> list=_projectService.GetAll().ToList();//获取所有数据,即上述列出的数据
  List<Project> data = new List<Project>();
  data.AddRange(rs.Where(p => p.parentId == -1).ToList());//将一级数据加入data中
  foreach (var item in data)
  {
        AddProjectChildren(item, rs);
  }
  return data;
  }

• AddProjectChildren 递归函数

  //关键1: 传入的model是对象,对象修改会直接影响引用的对象
  //关键2: 递归调用,直到传入的列表为空
  private Project AddProjectChildren(Project model, List<Project> typeList)
  {
      var treeList = new List<Project>();
      var list = typeList.Where(p => p.parentId == model.id).ToList();
      if (list.Count == 0) return null;
      foreach (var item in list)
      {
            treeList.Add(item);
            typeList.Remove(item);
       }
      model.children = treeList;
      foreach (var children in model.children)
      {
            AddProjectChildren(children, typeList);
      }
   return model;
  }

  结果

  [
      {
          "children": [
              {
                  "children": [
                      {
                        "children": [],
                        "id": 4,
                        "parentId": 2,
                        "name": "name4",
                    },
                  ],
                  "id": 2,
                  "parentId": 1,
                  "name": "name2",
              },
              {
                  "children": [],
                  "id": 3,
                  "parentId": 1,
                  "name": "name3",
              }
          ],
          "id": 1,
          "parentId": -1,
          "name": "name1",
      }
  ]