rocket_stove_yt_iframes

Rocket Stove YT Iframes: Python 3, Flask app, Jinja 2 template, csv.reader()

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Virtual Environment

A Python virtual environment helps prevent changes to system Python which would render an OS unstable. For example, if a Python module requires a previous version of a dependency, which system Python also uses, and then changes such an existing dependency to another version, system instability can result. So, a Python virtual environment can help contain a Python development within its own sandbox to help prevent it from knocking the swing set over or tilting the merry-go-round. For developers, virtual environments can become a system security measure of sorts.

Below, is an example of virtual environment creation:

user_foo@foo_host:~/Desktop$ python3 -m venv foo
user_foo@foo_host:~/Desktop$ cd foo
user_foo@foo_host:~/Desktop/foo$ ls -l
total 20
drwxrwxr-x 2 user_foo user_foo 4096 Jul  1 10:11 bin
drwxrwxr-x 2 user_foo user_foo 4096 Jul  1 09:30 include
drwxrwxr-x 3 user_foo user_foo 4096 Jul  1 09:30 lib
lrwxrwxrwx 1 user_foo user_foo    3 Jul  1 09:30 lib64 -> lib
-rw-rw-r-- 1 user_foo user_foo   69 Jul  1 10:10 pyvenv.cfg
drwxrwxr-x 3 user_foo user_foo 4096 Jul  1 10:10 share
$ source bin/activate
(foo) user_foo@foo_host:~/Desktop/foo$

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Run App

Navigate to the root directory of rocket_stove and run the app:

. .run.sh

#! /bin/dash

export FLASK_ENV=development
export FLASK_APP=rocket_stove
flask run

• dash is basically the same thing as bash, as they are both Unix shells, but dash is smaller.
• export FLASK_ENV=development environmental variable sets the Flask app to development mode, which includes a debugger.
• export FLASK_APP=rocket_stove environmental variable tells Flask which app to run.
• flask run starts the Flask app

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Shebang/Interpreter Directive

#! /bin/python3

First of all, the Unix shebang line is ignored by the Python executable file because that line starts with a # character which leads a comment string.

The shebang is actually a human-readable instance of a magic number in the executable file, the magic byte string being 0x23 0x21, the two-character encoding in ASCII of #!. This magic number is detected by the exec family of functions, which determine whether a file is a script or an executable binary. The presence of the shebang will result in the execution of the specified executable, usually an interpreter for the script's language.₁

In this case, the interpreter of the script's language is /bin/python3.

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Module __doc__

'''`rocket_stove` module contains `rocket_stove()` method which renders \
a template of YouTube links.'''

Python's interactive shell can be used to access that __doc__ string.

>>> __doc__
'`rocket_stove` module contains `rocket_stove()` method which renders a template of YouTube links.'

This documentation is used to describe the module.

The line break character \ can be added to restrict a newline character from appearing in the doc string.

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Imports

from csv import reader
from flask import Flask
from flask import render_template

• csv.reader() returns a reader object assigned to _reader which iterates over records in csv/rocket_stove.csv.
• A Flask app is an instance of the Flask class. Everything about the application, such as configuration and URLs, will be registered with Flask.
• flask.render_template() is used to render a Jinja 2 template.

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Variables

APP = Flask(__name__)  # initialize Flask instance
VIDEO_TITLE = []  # list of video titles
URL_PROF_MAT = {}  # dict values: URL, profile name, stove material

• APP = Flask(__name__) initializes the Flask instance.
• VIDEO_TITLE = [] initializes the list where video titles will be appended.
• URL_PROF_MAT = {} initializes dictionary where video title keys and URL values are assigned.

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rocket_stove() Method

rocket_stove module can be imported into the Python interactive shell, which enables access to the method's documentation, for example:

>>> import rocket_stove
>>> dir(rocket_stove)
['APP', 'Flask', 'URL_PROF_MAT', 'VIDEO_TITLE', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'reader', 'render_template', 'rocket_stove']
>>> rocket_stove.rocket_stove.__doc__
'`rocket_stove()` method renders list of YouTube links to a template.'

File I/O

• the open() built-in function opens csv/rocket_stove.csv for reading in text mode with 'UTF-8' encoding, as demonstrated below:

>>> open('csv/rocket_stove.csv')
<_io.TextIOWrapper name='csv/rocket_stove.csv' mode='r' encoding='UTF-8'>

CSV Reader

• csv.reader() returns a reader object which iterates over records in csv/rocket_stove.csv.

>>> _file = open('csv/rocket_stove.csv')
>>> rocket_stove.reader(_file)
<_csv.reader object at 0x7fea494d72e0>

• next(_reader) is used to skip the first row of the CSV file which is a title row, and which advances to the first record of the database in the second line. The first row of that database contains Title,URL.

Looping Structure

A for statement is used to iterate through the CSV reader object:

>>> _reader = rocket_stove.reader(_file)
>>> for i in _reader:
...     print(i)
...
['Title', 'URL']
['How To Make Rocket Stove', 'SYYSuHulf-4']
["World's Best Rocket Stove!! - How to Build a Simple Camp Stove", 'GMcDekiRKs8']
['5 Minute Rocket Stove', 'dwZitmJl7zY']
['How to design and make a Rocket Stove Griddle', 's_aKIs8sYPk']
['The Classic Rocket Stove Build', 'X8OOZuJcTFE']
['Hot Water Rocket Stove II - BUILD-', 'PBI4LaeKxDE']
['Hot Water Rocket Stove K Type Part 2', '7wRszNLpuc0']
['Vortex Rocket Stove Pt 1', 'UBIBW1z2gks']
['Rocket stove (Pellet; wood).3 in 1. 거꾸로 타는 난로 만들기', 'uQ2MP6ryYCw']
['Como hacer estufa Rocket. Paso a paso / Handmade rocket stove.', 'JQ8axWRoEtA']
['Homemade wood burning Rocket stove', '9-r4VLHQRlM']
['The Best Homemade Rocket Stove', 'B-9qo6P4NQU']
['로켓스토브 고기불판 (Rocket stove)', 'jjsObiA3Heg']
['立佳設計工坊 - 火箭爐 Rocket stove', 'ug7jmoHf-Bg']
['Brick Rocket Stove Build And Water Boil Test vs Stove Top', 'Z_Rozs12174']
['DIY Brick Rocket Stove - Cooking Without Electrical Power', 'onMbSLuC7Oc']
['How to build a better brick rocket stove for $10', 'r66jjYdBmg8']
['Build Your Own Brick Rocket Stove', 'GRZM8pdsjyc']
['J shaped gravity fed brick rocket stove', 'v26b3jrylEc']
['Rocket stove en briques', 'TqW5Kse3ft0']
['How To Make A Concrete And Perlite Rocket Stove', 'TYr-Uj4HqDs']

Variables

• VIDEO_TITLE is a list of all of the video titles which will also be used as keys to select the associated URLs.
• URL contains key/value pairs of video titles/URLs, e.g. 'How To Make Rocket Stove': ['SYYSuHulf-4']

>>> VIDEO_TITLE = []
>>> URL = {}
>>> import rocket_stove
>>> _file = open('csv/rocket_stove.csv')
>>> _reader = rocket_stove.reader(_file)
>>> for record in _reader:
...     VIDEO_TITLE.append(record[0])
...     URL_PROF_MAT[record[0]] = [record[1]]
...
>>> VIDEO_TITLE
['Title', 'How To Make Rocket Stove', "World's Best Rocket Stove!! - How to Build a Simple Camp Stove", '5 Minute Rocket Stove', 'How to design and make a Rocket Stove Griddle', 'The Classic Rocket Stove Build', 'Hot Water Rocket Stove II - BUILD-', 'Hot Water Rocket Stove K Type Part 2', 'Vortex Rocket Stove Pt 1', 'Rocket stove (Pellet; wood).3 in 1. 거꾸로 타는 난로 만들기', 'Como hacer estufa Rocket. Paso a paso / Handmade rocket stove.', 'Homemade wood burning Rocket stove', 'The Best Homemade Rocket Stove', '로켓스토브 고기불판 (Rocket stove)', '立佳設計工坊 - 火箭爐 Rocket stove', 'Brick Rocket Stove Build And Water Boil Test vs Stove Top', 'DIY Brick Rocket Stove - Cooking Without Electrical Power', 'How to build a better brick rocket stove for $10', 'Build Your Own Brick Rocket Stove', 'J shaped gravity fed brick rocket stove', 'Rocket stove en briques', 'How To Make A Concrete And Perlite Rocket Stove']
>>> URL_PROF_MAT
{'Title': ['URL'], 'How To Make Rocket Stove': ['SYYSuHulf-4'], "World's Best Rocket Stove!! - How to Build a Simple Camp Stove": ['GMcDekiRKs8'], '5 Minute Rocket Stove': ['dwZitmJl7zY'], 'How to design and make a Rocket Stove Griddle': ['s_aKIs8sYPk'], 'The Classic Rocket Stove Build': ['X8OOZuJcTFE'], 'Hot Water Rocket Stove II - BUILD-': ['PBI4LaeKxDE'], 'Hot Water Rocket Stove K Type Part 2': ['7wRszNLpuc0'], 'Vortex Rocket Stove Pt 1': ['UBIBW1z2gks'], 'Rocket stove (Pellet; wood).3 in 1. 거꾸로 타는 난로 만들기': ['uQ2MP6ryYCw'], 'Como hacer estufa Rocket. Paso a paso / Handmade rocket stove.': ['JQ8axWRoEtA'], 'Homemade wood burning Rocket stove': ['9-r4VLHQRlM'], 'The Best Homemade Rocket Stove': ['B-9qo6P4NQU'], '로켓스토브 고기불판 (Rocket stove)': ['jjsObiA3Heg'], '立佳設計工坊 - 火箭爐 Rocket stove': ['ug7jmoHf-Bg'], 'Brick Rocket Stove Build And Water Boil Test vs Stove Top': ['Z_Rozs12174'], 'DIY Brick Rocket Stove - Cooking Without Electrical Power': ['onMbSLuC7Oc'], 'How to build a better brick rocket stove for $10': ['r66jjYdBmg8'], 'Build Your Own Brick Rocket Stove': ['GRZM8pdsjyc'], 'J shaped gravity fed brick rocket stove': ['v26b3jrylEc'], 'Rocket stove en briques': ['TqW5Kse3ft0'], 'How To Make A Concrete And Perlite Rocket Stove': ['TYr-Uj4HqDs']}

Render Template

• render_template('template.htm', video_title=VIDEO_TITLE, url=URL) renders the Jinja2 template.

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¹ magic number