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

• 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",
    }
]