Category & Subcategory In Pyhton

0-PY-CATEGORY.MD

PYTHON CATEGORY & SUBCATEGORY

https://code-boxx.com/categories-subcategories-python/

NOTES

1. Run unpack.bat (Windows) unpack.sh (Linux/Mac). This will automatically:
   • Create a virtual environment - virtualenv venv.
   • Activate the virtual environment - venv\scripts\activate (Windows) venv/bin/activate (Mac/Linux)
   • Run python S1B_create.py to create the category database.
   • Run python S3_draw.py and draw the nested categories.
2. Also see S4_actions.py for the "admin functions".

LICENSE

Copyright by Code Boxx

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

S1A_category.sql

CREATE TABLE category (
  category_id INTEGER,
  parent_id INTEGER DEFAULT 0,
  category_name TEXT NOT NULL,
  PRIMARY KEY("category_id" AUTOINCREMENT)
);
CREATE INDEX parent_id ON category (parent_id);

INSERT INTO `category` (`category_id`, `parent_id`, `category_name`) VALUES
(1, 0, 'Electronics'),
(2, 1, 'Computers'),
(3, 1, 'Cameras'),
(4, 2, 'Desktop'),
(5, 2, 'Laptop');

S1B_create.py

# (A) LOAD PACKAGES
import sqlite3, os
from sqlite3 import Error

# (B) DATABASE + SQL FILE
DBFILE = "category.db"
SQLFILE = "S1A_category.sql"

# (C) DELETE OLD DATABASE IF EXIST
if os.path.exists(DBFILE):
  os.remove(DBFILE)

# (D) IMPORT SQL
conn = sqlite3.connect(DBFILE)
with open(SQLFILE) as f:
  conn.executescript(f.read())
conn.commit()
conn.close()
print("Database created!")

S2_lib.py

# (A) LOAD SQLITE MODULE
import sqlite3
DBFILE = "category.db"

# (B) GET CATEGORIES
def get (parent=0):
  # (B1) CONNECT
  conn = sqlite3.connect(DBFILE)
  cursor = conn.cursor()

  # (B2) GET CATEGORY WITH PARENT ID
  cursor.execute(
    "SELECT * FROM `category` WHERE `parent_id`=?",
    (parent,)
  )
  rows = cursor.fetchall()

  # (B3) NO CHILDREN IN THIS CATEGORY
  if len(rows)==0:
    return None

  # (B4) ARRANGE DATA & RECURSIVE
  data = {}
  for r in rows:
    data[r[0]] = {
      "n" : r[2],
      "c" : get(r[0])
    }
  return data

# (C) SAVE CATEGORY
def save (name, parent, id=None):
  # (C1) CONNECT TO DATABASE
  conn = sqlite3.connect(DBFILE)
  cursor = conn.cursor()

  # (C2) ADD OR UPDATE SQL
  if id is None:
    sql = "INSERT INTO `category` (`category_name`, `parent_id`) VALUES (?,?)"
    data = (name, parent,)
  else:
    sql = "UPDATE `category` SET `category_name`=?, `parent_id`=? WHERE `category_id`=?"
    data = (name, parent, id,)

  # (C3) GO!
  cursor.execute(sql, data)
  conn.commit()
  conn.close()
  return True

# (D) GET CHILD CATEGORIES
def getchildren (id):
  conn = sqlite3.connect(DBFILE)
  cursor = conn.cursor()
  cursor.execute(
    "SELECT `category_id` FROM `category` WHERE `parent_id`=?",
    (id,)
  )
  cat = ()
  for r in cursor.fetchall():
    cat = cat + r
  for id in cat:
    cat = cat + getchildren(id)
  return cat

# (E) GET "LEGAL" PARENT IDS
def getswitchable (id):
  # (E1) PARENT ID CANNOT BE SELF AND CHILDREN
  illegal = getchildren(id)
  illegal = illegal + (id,)
  illegal = ",".join([str(v) for v in illegal])

  # (E2) GET ALL "LEGAL" PARENT ID
  conn = sqlite3.connect(DBFILE)
  cursor = conn.cursor()
  cursor.execute(f"SELECT `category_id` FROM `category` WHERE `category_id` NOT IN ({illegal})")
  cat = (0,)
  for r in cursor.fetchall():
    cat = cat + r
  return cat

# (F) DELETE CATEGORY
def delete (id):
  # (F1) CONNECT TO DATABASE
  conn = sqlite3.connect(DBFILE)
  cursor = conn.cursor()

  # (F2) REVERT ALL CHILDREN TO ROOT
  children = getchildren(id)
  if (len(children)>0):
    children = ",".join([str(v) for v in children])
    cursor.execute(f"UPDATE `category` SET `parent_id`=0 WHERE `category_id` IN ({children})")

  # (F3) DELETE CATEGORY
  cursor.execute(
    "DELETE FROM `category` WHERE `category_id`=?",
    (id,)
  )
  conn.commit()
  conn.close()
  return True

S3_draw.py

# (A) LOAD MODULES
import S2_lib as cat

# (B) DRAW CATEGORIES
def draw (data, level=0):
  for id, cat in data.items():
    # (B1) INDENTATION
    if level>0:
      for i in range(level):
        print(" ", end="")

    # (B2) CATEGORY ID & NAME
    print(f"({id}) {cat['n']}")
    if cat["c"] is not None:
      draw(cat["c"], level+1)

# (C) GO!
draw(cat.get())

S4_actions.py

# (A) LOAD MODULES
import S2_lib as cat

# (B) ADD A NEW CATEGORY
#cat.save("Smartphones", 2)
#cat.save("Tablets", 2)

# (C) UPDATE CATEGORY
#all = cat.getswitchable(2)
#print(all)
#cat.save("Computerzzz", 3, 2)

# (D) DELETE CATEGORY
cat.delete(2)

unpack.bat

virtualenv venv
call venv\Scripts\activate
python S1B_create.py
python S3_draw.py

unpack.sh

virtualenv venv
source "venv/bin/activate"
python S1B_create.py
python S3_draw.py