search
HomeBackend DevelopmentPython TutorialDetailed explanation of python recursive query menu and conversion into json example code

This article mainly introduces the python recursive query menu and converts it into a json instance. It has certain reference value. Interested friends can refer to it.

I recently needed to write a menu in python, and it took me two or three days to get it done. Now I record it here, and friends who need it can learn from it.

Note: The article quotes the complete non-executable code and only excerpts the key parts of the code

Environment

  • Database: mysql

  • python:3.6

Table structure


CREATE TABLE `tb_menu` (
 `id` varchar(32) NOT NULL COMMENT '唯一标识',
 `menu_name` varchar(40) DEFAULT NULL COMMENT '菜单名称',
 `menu_url` varchar(100) DEFAULT NULL COMMENT '菜单链接',
 `type` varchar(1) DEFAULT NULL COMMENT '类型',
 `parent` varchar(32) DEFAULT NULL COMMENT '父级目录id',
 `del_flag` varchar(1) NOT NULL DEFAULT '0' COMMENT '删除标志 0:不删除 1:已删除',
 `create_time` datetime DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
 `update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间',
 PRIMARY KEY (`id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='菜单表';

Python code

In the Menu object, there is a reference to the submenu list "subMenus", the type is list

Core code


def set_subMenus(id, menus):
  """
  根据传递过来的父菜单id,递归设置各层次父菜单的子菜单列表

  :param id: 父级id
  :param menus: 子菜单列表
  :return: 如果这个菜单没有子菜单,返回None;如果有子菜单,返回子菜单列表
  """
  # 记录子菜单列表
  subMenus = []
  # 遍历子菜单
  for m in menus:
    if m.parent == id:
      subMenus.append(m)

  # 把子菜单的子菜单再循环一遍
  for sub in subMenus:
    menus2 = queryByParent(sub.id)
    # 还有子菜单
    if len(menus):
      sub.subMenus = set_subMenus(sub.id, menus2)

  # 子菜单列表不为空
  if len(subMenus):
    return subMenus
  else: # 没有子菜单了
    return None

Test method


  def test_set_subMenus(self):
    # 一级菜单
    rootMenus = queryByParent('')
    for menu in rootMenus:
      subMenus = queryByParent(menu.id)
      menu.subMenus = set_subMenus(menu.id, subMenus)

Note: The basic process is: first query the first-level menu, Then pass the id of the menu at this level and the submenu list of this level menu to the set_subMenus method to recursively set the lower-level menus of the submenu list;

supports passing the menu ID and querying the menu below. All submenus. If you pass a null character, the query starts from the root directory

In the "rootMenus" object, you can see the complete menu tree structure

Convert to Json

The ORM framework I use is: sqlalchemy. The Menu object queried directly from the database will report an error when it is converted to Json. A DTO class needs to be redefined to convert the Menu object into a Dto object.

MenuDto


class MenuDto():
  def __init__(self, id, menu_name, menu_url, type, parent, subMenus):
    super().__init__()
    self.id = id
    self.menu_name = menu_name
    self.menu_url = menu_url
    self.type = type
    self.parent = parent
    self.subMenus = subMenus

  def __str__(self):
    return '%s(id=%s,menu_name=%s,menu_url=%s,type=%s,parent=%s)' % (
      self.__class__.__name__, self.id, self.menu_name, self.menu_url, self.type, self.parent)

  __repr = __str__

So, the method of recursively setting submenus was redefined


def set_subMenuDtos(id, menuDtos):
  """
  根据传递过来的父菜单id,递归设置各层次父菜单的子菜单列表

  :param id: 父级id
  :param menuDtos: 子菜单列表
  :return: 如果这个菜单没有子菜单,返回None;如果有子菜单,返回子菜单列表
  """
  # 记录子菜单列表
  subMenuDtos = []
  # 遍历子菜单
  for m in menuDtos:
    m.name = to_pinyin(m.menu_name)
    if m.parent == id:
      subMenuDtos.append(m)

  # 把子菜单的子菜单再循环一遍
  for sub in subMenuDtos:
    menus2 = queryByParent(sub.id)
    menusDto2 = model_list_2_dto_list(menus2,
                     "MenuDto(id='', menu_name='', menu_url='', type='', parent='', subMenus='')")
    # 还有子菜单
    if len(menuDtos):
      if len(menusDto2):
        sub.subMenus = set_subMenuDtos(sub.id, menusDto2)
      else: # 没有子菜单,删除该节点
        sub.__delattr__('subMenus')

  # 子菜单列表不为空
  if len(subMenuDtos):
    return subMenuDtos
  else: # 没有子菜单了
    return None

Note:

  1. When a menu has no submenus, delete the "subMenus" attribute, otherwise a null value will appear when converting to Json

  2. model_list_2_dto_list method can convert Menu list into MenuDto list

  3. to_pinyin is a method to convert Chinese characters into pinyin, no need to pay attention here

View layer's method of returning Json


  def get(self):
    param = request.args
    id = param['id']
    # 如果id为空,查询的是从根目录开始的各级菜单
    rootMenus = queryByParent(id)
    rootMenuDtos = model_list_2_dto_list(rootMenus,
                       "MenuDto(id='', menu_name='', menu_url='', type='', parent='', subMenus='')")
    # 设置各级子菜单
    for menu in rootMenuDtos:
      menu.name = to_pinyin(menu.menu_name)
      subMenus = queryByParent(menu.id)
      if len(subMenus):
        subMenuDtos = model_list_2_dto_list(subMenus,
                          "MenuDto(id='', menu_name='', menu_url='', type='', parent='', subMenus='')")
        menu.subMenus = set_subMenuDtos(menu.id, subMenuDtos)
      else:
        menu.__delattr__('subMenus')

    menus_json = json.dumps(rootMenuDtos, default=lambda o: o.__dict__, sort_keys=True, allow_nan=false,
                skipkeys=true)
    # 需要转字典,否则返回的字符串会带有“\”
    menus_dict = json_dict(menus_json)
    return fullResponse(menus_dict)
fullResponse

from flask import jsonify


def fullResponse(data='', msg='', code=0):
  if msg == '':
    return jsonify({'code': code, 'data': data})
  elif data == '':
    return jsonify({'code': code, 'msg': msg})
  else:
    return jsonify({'code': code, 'msg': msg, 'data': data})

Note: The meanings of json and dictionary in python are similar. When json is finally returned to the page, You need to use the json_dict method to convert to dict type first, otherwise the returned string will contain "\"

Query results

Detailed explanation of python recursive query menu and conversion into json example code

The above is the detailed content of Detailed explanation of python recursive query menu and conversion into json example code. For more information, please follow other related articles on the PHP Chinese website!

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
How to Use Python to Find the Zipf Distribution of a Text FileHow to Use Python to Find the Zipf Distribution of a Text FileMar 05, 2025 am 09:58 AM

This tutorial demonstrates how to use Python to process the statistical concept of Zipf's law and demonstrates the efficiency of Python's reading and sorting large text files when processing the law. You may be wondering what the term Zipf distribution means. To understand this term, we first need to define Zipf's law. Don't worry, I'll try to simplify the instructions. Zipf's Law Zipf's law simply means: in a large natural language corpus, the most frequently occurring words appear about twice as frequently as the second frequent words, three times as the third frequent words, four times as the fourth frequent words, and so on. Let's look at an example. If you look at the Brown corpus in American English, you will notice that the most frequent word is "th

How Do I Use Beautiful Soup to Parse HTML?How Do I Use Beautiful Soup to Parse HTML?Mar 10, 2025 pm 06:54 PM

This article explains how to use Beautiful Soup, a Python library, to parse HTML. It details common methods like find(), find_all(), select(), and get_text() for data extraction, handling of diverse HTML structures and errors, and alternatives (Sel

Image Filtering in PythonImage Filtering in PythonMar 03, 2025 am 09:44 AM

Dealing with noisy images is a common problem, especially with mobile phone or low-resolution camera photos. This tutorial explores image filtering techniques in Python using OpenCV to tackle this issue. Image Filtering: A Powerful Tool Image filter

How to Work With PDF Documents Using PythonHow to Work With PDF Documents Using PythonMar 02, 2025 am 09:54 AM

PDF files are popular for their cross-platform compatibility, with content and layout consistent across operating systems, reading devices and software. However, unlike Python processing plain text files, PDF files are binary files with more complex structures and contain elements such as fonts, colors, and images. Fortunately, it is not difficult to process PDF files with Python's external modules. This article will use the PyPDF2 module to demonstrate how to open a PDF file, print a page, and extract text. For the creation and editing of PDF files, please refer to another tutorial from me. Preparation The core lies in using external module PyPDF2. First, install it using pip: pip is P

How to Cache Using Redis in Django ApplicationsHow to Cache Using Redis in Django ApplicationsMar 02, 2025 am 10:10 AM

This tutorial demonstrates how to leverage Redis caching to boost the performance of Python applications, specifically within a Django framework. We'll cover Redis installation, Django configuration, and performance comparisons to highlight the bene

How to Perform Deep Learning with TensorFlow or PyTorch?How to Perform Deep Learning with TensorFlow or PyTorch?Mar 10, 2025 pm 06:52 PM

This article compares TensorFlow and PyTorch for deep learning. It details the steps involved: data preparation, model building, training, evaluation, and deployment. Key differences between the frameworks, particularly regarding computational grap

Introduction to Parallel and Concurrent Programming in PythonIntroduction to Parallel and Concurrent Programming in PythonMar 03, 2025 am 10:32 AM

Python, a favorite for data science and processing, offers a rich ecosystem for high-performance computing. However, parallel programming in Python presents unique challenges. This tutorial explores these challenges, focusing on the Global Interprete

How to Implement Your Own Data Structure in PythonHow to Implement Your Own Data Structure in PythonMar 03, 2025 am 09:28 AM

This tutorial demonstrates creating a custom pipeline data structure in Python 3, leveraging classes and operator overloading for enhanced functionality. The pipeline's flexibility lies in its ability to apply a series of functions to a data set, ge

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
2 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
Repo: How To Revive Teammates
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌
Hello Kitty Island Adventure: How To Get Giant Seeds
4 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

ZendStudio 13.5.1 Mac

ZendStudio 13.5.1 Mac

Powerful PHP integrated development environment

Safe Exam Browser

Safe Exam Browser

Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool