code-boxx/0-PY-DEPENDENT-DROPDOWN.MD

## 0-PY-DEPENDENT-DROPDOWN.MD

      
    Raw
  

              0-PY-DEPENDENT-DROPDOWN.MD
            
          
    PYTHON FLASK DEPENDENT DROPDOWN

https://code-boxx.com/python-flask-dependent-dropdown/
NOTES


Run unpack.bat (Windows) unpack.sh (Linux/Mac). This will automatically:

Create 2 folders - static, templates
Move S3B_selector.js and S3C_selector.css into static.
Move S3A_selector.html into templates.
Create a virtual environment - virtualenv venv
Activate the virtual environment - venv\scripts\activate (Windows) venv/bin/activate (Mac/Linux)
Install Flask pip install flask
Create the database python S1B_create.py
Start the server python S1_server.py


Access http://localhost in your browser.

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_cat.sql
-- (A) CATEGORY TABLE
CREATE TABLE `category` (
  `id` INTEGER PRIMARY KEY AUTOINCREMENT,
  `parent` INTEGER DEFAULT 0 NOT NULL,
  `name` TEXT NOT NULL
);
CREATE INDEX `idx_parent` ON `category` (`parent`);

-- (B) DUMMY CATEGORIES
INSERT INTO `category` (`id`, `parent`, `name`) VALUES
(1, 0, 'Electronics'),
(2, 0, 'Sports'),
(3, 1, 'Mobile'),
(4, 1, 'Tablet'),
(5, 1, 'Laptop'),
(6, 1, 'Desktop'),
(7, 2, 'Jogging'),
(8, 2, 'Swimming'),
(9, 2, 'Cycling');

## S1B_create.py
# (A) LOAD PACKAGES
import sqlite3, os
from sqlite3 import Error

# (B) DATABASE + SQL FILE
DBFILE = "cat.db"
SQLFILE = "S1A_cat.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_server.py
# (A) INIT
# (A1) LOAD MODULES
from flask import Flask, request, render_template
import sqlite3, json

# (A2) FLASK SETTINGS + INIT
DBFILE = "cat.db"
HOST_NAME = "localhost"
HOST_PORT = 80
app = Flask(__name__)
# app.debug = True

# (B) ROUTES
# (B1) SERVE DEMO PAGE
@app.route("/")
def demo():
  return render_template("S3A_selector.html")

# (B2) GET CATEGORIES FROM DATABASE
@app.route("/getcat", methods=["POST"])
def getcat():
  data = dict(request.form)
  conn = sqlite3.connect(DBFILE)
  cat = conn.cursor().execute("SELECT `id`, `name` FROM `category` WHERE `parent`=?", (data["id"],)).fetchall()
  conn.close()
  return json.dumps(cat)

# (C) START
if __name__ == "__main__":
  app.run(HOST_NAME, HOST_PORT)

## S3A_selector.html
<!DOCTYPE html>
<html>
  <head>
    <title>Dependent Dropdown Selector</title>
    <meta charset="utf-8">
    <script src="static/S3B_selector.js"></script>
    <link rel="stylesheet" href="static/S3C_selector.css">
  </head>
  <body>
    <form onsubmit="return false;">
      <label>Main Category</label>
      <select id="cat1" onchange="loadcat(2)"></select>

      <label>Sub Category</label>
      <select id="cat2"></select>
    </form>
  </body>
</html>

## S3B_selector.js
// (A) LOAD CATEGORY SELECTOR
// level 1 = main category
// level 2 = sub category
function loadcat (level) {
  // (A1) GET SELECTED PARENT ID
  var data = new FormData();
  data.append("id", (level==1 ? 0 : document.getElementById("cat1").value));

  // (A2) AJAX FETCH CATEGORIES
  fetch("/getcat", { method: "POST", body: data })
  .then(res => res.json())
  .then(cat => {
    // (A2-1) UPDATE HTML SELECTOR
    let selector = document.getElementById("cat" + level);
    selector.innerHTML = "";
    for (let c of cat) {
      let opt = document.createElement("option");
      opt.value = c[0];
      opt.innerHTML = c[1];
      selector.appendChild(opt);
    }

    // (A2-2) CASCADE LOAD SUB-CATEGORY
    if (level==1) { loadcat(2); }
  });
}

// (B) INIT LOAD
window.onload = () => loadcat(1);

## S3C_selector.css
/* (X) DOES NOT MATTER */
* {
  font-family: Arial, Helvetica, sans-serif;
  box-sizing: border-box;
}
form {
  max-width: 400px;
  padding: 30px 20px;
  border: 1px solid #e1e1e1;
  background: #f2f2f2;
}
label, select {
  display: block;
  width: 100%;
}
label {
  margin: 10px 0;
  color: #4a4a4a;
}
form label:first-child { margin-top: 0; }
select {
  padding: 10px;
  border: 1px solid #d5d5d5;
}

## unpack.bat
md templates
md static
move S3A_selector.html templates
move S3B_selector.js static
move S3C_selector.css static
virtualenv venv
call venv\Scripts\activate
pip install flask
python S1B_create.py
python S2_server.py

## unpack.sh
mkdir -m 777 templates
mkdir -m 777 static
mv ./S3A_selector.html ./templates
mv ./S3B_selector.js ./static
mv ./S3C_selector.css ./static
virtualenv venv
source "venv/bin/activate"
pip install flask
python S1B_create.py
python S2_server.py
	-- (A) CATEGORY TABLE
	CREATE TABLE `category` (
	`id` INTEGER PRIMARY KEY AUTOINCREMENT,
	`parent` INTEGER DEFAULT 0 NOT NULL,
	`name` TEXT NOT NULL
	);
	CREATE INDEX `idx_parent` ON `category` (`parent`);

	-- (B) DUMMY CATEGORIES
	INSERT INTO `category` (`id`, `parent`, `name`) VALUES
	(1, 0, 'Electronics'),
	(2, 0, 'Sports'),
	(3, 1, 'Mobile'),
	(4, 1, 'Tablet'),
	(5, 1, 'Laptop'),
	(6, 1, 'Desktop'),
	(7, 2, 'Jogging'),
	(8, 2, 'Swimming'),
	(9, 2, 'Cycling');
	# (A) LOAD PACKAGES
	import sqlite3, os
	from sqlite3 import Error

	# (B) DATABASE + SQL FILE
	DBFILE = "cat.db"
	SQLFILE = "S1A_cat.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!")
	# (A) INIT
	# (A1) LOAD MODULES
	from flask import Flask, request, render_template
	import sqlite3, json

	# (A2) FLASK SETTINGS + INIT
	DBFILE = "cat.db"
	HOST_NAME = "localhost"
	HOST_PORT = 80
	app = Flask(__name__)
	# app.debug = True

	# (B) ROUTES
	# (B1) SERVE DEMO PAGE
	@app.route("/")
	def demo():
	return render_template("S3A_selector.html")

	# (B2) GET CATEGORIES FROM DATABASE
	@app.route("/getcat", methods=["POST"])
	def getcat():
	data = dict(request.form)
	conn = sqlite3.connect(DBFILE)
	cat = conn.cursor().execute("SELECT `id`, `name` FROM `category` WHERE `parent`=?", (data["id"],)).fetchall()
	conn.close()
	return json.dumps(cat)

	# (C) START
	if __name__ == "__main__":
	app.run(HOST_NAME, HOST_PORT)
	<!DOCTYPE html>
	<html>
	<head>
	<title>Dependent Dropdown Selector</title>
	<meta charset="utf-8">
	<script src="static/S3B_selector.js"></script>
	<link rel="stylesheet" href="static/S3C_selector.css">
	</head>
	<body>
	<form onsubmit="return false;">
	<label>Main Category</label>
	<select id="cat1" onchange="loadcat(2)"></select>

	<label>Sub Category</label>
	<select id="cat2"></select>
	</form>
	</body>
	</html>
	// (A) LOAD CATEGORY SELECTOR
	// level 1 = main category
	// level 2 = sub category
	function loadcat (level) {
	// (A1) GET SELECTED PARENT ID
	var data = new FormData();
	data.append("id", (level==1 ? 0 : document.getElementById("cat1").value));

	// (A2) AJAX FETCH CATEGORIES
	fetch("/getcat", { method: "POST", body: data })
	.then(res => res.json())
	.then(cat => {
	// (A2-1) UPDATE HTML SELECTOR
	let selector = document.getElementById("cat" + level);
	selector.innerHTML = "";
	for (let c of cat) {
	let opt = document.createElement("option");
	opt.value = c[0];
	opt.innerHTML = c[1];
	selector.appendChild(opt);
	}

	// (A2-2) CASCADE LOAD SUB-CATEGORY
	if (level==1) { loadcat(2); }
	});
	}

	// (B) INIT LOAD
	window.onload = () => loadcat(1);
	/* (X) DOES NOT MATTER */
	* {
	font-family: Arial, Helvetica, sans-serif;
	box-sizing: border-box;
	}
	form {
	max-width: 400px;
	padding: 30px 20px;
	border: 1px solid #e1e1e1;
	background: #f2f2f2;
	}
	label, select {
	display: block;
	width: 100%;
	}
	label {
	margin: 10px 0;
	color: #4a4a4a;
	}
	form label:first-child { margin-top: 0; }
	select {
	padding: 10px;
	border: 1px solid #d5d5d5;
	}
	md templates
	md static
	move S3A_selector.html templates
	move S3B_selector.js static
	move S3C_selector.css static
	virtualenv venv
	call venv\Scripts\activate
	pip install flask
	python S1B_create.py
	python S2_server.py
	mkdir -m 777 templates
	mkdir -m 777 static
	mv ./S3A_selector.html ./templates
	mv ./S3B_selector.js ./static
	mv ./S3C_selector.css ./static
	virtualenv venv
	source "venv/bin/activate"
	pip install flask
	python S1B_create.py
	python S2_server.py