樹形結構:首先是構造一種層級關系,主要用於層級菜單,或是一種遞進的情況.

例:下面是一種層級關系,Pid字段後面的數字,指定的就是id數字的子層級.Pid等於None是根目錄.
comment_list=[

    {"id":1,"content":"...","Pid":None,"children_comments":[]},
    {"id":2,"content":"...","Pid":None,"children_comments":[]},
    {"id":3,"content":"...","Pid":None,"children_comments":[]},
    {
 
"id":4,"content":"...","Pid":1,"children_comments":[]},
    {"id":5,"content":"...","Pid":1,"children_comments":[]},
    {"id":6,"content":"...","Pid":4,"children_comments":[]},
    {"id":7,"content":"...","Pid":3,"children_comments":[]},
    {"id":8,"content":"...","Pid":7,"children_comments":[]},
    {
 
"id":9,"content":"...","Pid":None,"children_comments":[]},
]

首先把他們變成鍵值對,放在字典裏.
comment_dict={}
    
for i in comment_list:
    comment_list[i["id"]]=i   #comment_dict的值就變成 ={1:{"id":1,"content":"...","Pid":None,"children_comments":[]},2:{"id":2,"content":"...","Pid":None,"children_comments":[]}...}

ret=[]
for comment in comment_list:
　　pid=comment[‘Pid‘]
　　if pid:  #當pid字段不為空
　　　　comment_dict[pid][‘children_comments‘].append(comment)   #pid值不為空,就是別人的子集,所以添加到相應父級的children_comments下.
　　else:
　　　　ret.append(comment)　　　　　　　　　　#把一些不要的數據取出來,
   
樹形結構,利用的就是可變類型結構.
字典和列表類型,當你賦值給一個變量後,當在別的時候變化,他原來的代碼也會跟著改變.
 

django-樹形結構