Alexey Rogachev arogachev

Django Migrations without Downtime

The following instructions describe a set of processes allowing you to run Django database migrations against a production database without having to bring the web service down.

Note that in the below instructions, migrations are all run manually at explicit points, and are not an automatic part of the deployment process.

Adding Fields or Tables

Adding a (nullable) field or a new table

Make the model or column addition in your code.

Intro

This is a basic collection of things I do when setting up a new headless ubuntu machine as a webserver. Following the steps below should give you a reasonable secure server with HTTP/2 support (including ALPN in chrome) and the fast NGINX server. I am happy to add things so leave a comment.

Basics

After creating the server (droplet on DigitalOcean) log in with

Python 2.7. Unicode Errors Simply Explained

I know I'm late with this article for about 5 years or so, but people are still using Python 2.x, so this subject is relevant I think.

Some facts first:

Unicode is an international encoding standard for use with different languages and scripts
In python-2.x, there are two types that deal with text.
1. str is an 8-bit string.

unicode is for strings of unicode code points.

	// This injects a box into the page that moves with the mouse;
	// Useful for debugging
	async function installMouseHelper(page) {
	await page.evaluateOnNewDocument(() => {
	// Install mouse helper only for top-level frame.
	if (window !== window.parent)
	return;
	window.addEventListener('DOMContentLoaded', () => {
	const box = document.createElement('puppeteer-mouse-pointer');
	const styleElement = document.createElement('style');

	const autoprefixer = require('autoprefixer');
	const webpack = require('webpack');
	const path = require('path');
	const precss = require('precss');

	const TransferWebpackPlugin = require('transfer-webpack-plugin');
	const ExtractTextPlugin = require('extract-text-webpack-plugin');

	module.exports = {
	devtool: 'eval',

	# Set inotify watch limit high enough for IntelliJ IDEA (PhpStorm, PyCharm, RubyMine, WebStorm).
	# Create this file as /etc/sysctl.d/60-jetbrains.conf (Debian, Ubuntu), and
	# run `sudo service procps start` or reboot.
	# Source: https://confluence.jetbrains.com/display/IDEADEV/Inotify+Watches+Limit
	#
	# More information resources:
	# -$ man inotify # manpage
	# -$ man sysctl.conf # manpage
	# -$ cat /proc/sys/fs/inotify/max_user_watches # print current value in use

	# The command finds the most recent tag that is reachable from a commit.
	# If the tag points to the commit, then only the tag is shown.
	# Otherwise, it suffixes the tag name with the number of additional commits on top of the tagged object
	# and the abbreviated object name of the most recent commit.
	git describe

	# With --abbrev set to 0, the command can be used to find the closest tagname without any suffix:
	git describe --abbrev=0

	# other examples

	vagrantfile:
	target: local
	vm:
	box: puphpet/ubuntu1404-x64
	box_url: puphpet/ubuntu1404-x64
	hostname: vagrant.local
	memory: '256'
	cpus: '1'
	chosen_provider: virtualbox
	network:

	class NonHtmlDebugToolbarMiddleware(object):
	"""
	The Django Debug Toolbar usually only works for views that return HTML.
	This middleware wraps any JSON response in HTML if the request
	has a 'debug' query parameter (e.g. http://localhost/foo?debug)
	"""

	@staticmethod
	def process_response(request, response):
	if request.GET.get('debug'):

	/**
	* Convert Excel file to Sheets
	* @param {Blob} excelFile The Excel file blob data; Required
	* @param {String} filename File name on uploading drive; Required
	* @param {Array} arrParents Array of folder ids to put converted file in; Optional, will default to Drive root folder
	* @return {Spreadsheet} Converted Google Spreadsheet instance
	**/
	function convertExcel2Sheets(excelFile, filename, arrParents) {

	var parents = arrParents \|\| []; // check if optional arrParents argument was provided, default to empty array if not