Today I Learned

My Today I Learned snippets. Inspired by jbranchaud/til, which I spotted on Hacker News.

Search these TILs at https://til.simonwillison.net/

github-actions

• Only run GitHub Action on push to master / main - 2020-04-19
• Dump out all GitHub Actions context - 2020-04-19
• Set environment variables for all steps in a GitHub Action - 2020-04-19
• Commit a file if it changed - 2020-04-19
• Running different steps on a schedule - 2020-04-20
• Updating a Markdown table of contents with a GitHub Action - 2020-07-22
• Using grep to write tests in CI - 2020-08-19
• Skipping a GitHub Actions step without failing - 2020-08-22
• Open a debugging shell in GitHub Actions with tmate - 2020-09-14
• Talking to a PostgreSQL service container from inside a Docker container - 2020-09-18
• Using Prettier to check JavaScript code style in GitHub Actions - 2020-12-31
• Running tests against PostgreSQL in a service container - 2021-02-23

python

• Convert a datetime object to UTC without using pytz - 2020-04-19
• macOS Catalina sort-of includes Python 3 - 2020-04-21
• Generated a summary of nested JSON data - 2020-04-28
• Installing and upgrading Datasette plugins with pipx - 2020-05-04
• Use setup.py to install platform-specific dependencies - 2020-05-05
• Build the official Python documentation locally - 2020-05-08
• Introspecting Python function parameters - 2020-05-27
• Password hashing in Python with pbkdf2 - 2020-07-13
• How to call pip programatically from Python - 2020-08-11
• Outputting JSON with reduced floating point precision - 2020-08-21
• Debugging a Click application using pdb - 2020-09-03
• Understanding option names in Click - 2020-09-22
• Explicit file encodings using click.File - 2020-10-16
• Decorators with optional arguments - 2020-10-28
• Running Python code in a subprocess with a time limit - 2020-12-06
• Controlling the style of dumped YAML using PyYAML - 2020-12-07
• Relinquishing control in Python asyncio - 2020-12-29
• Packaging a Python app as a standalone binary with PyInstaller - 2021-01-04
• Handling CSV files with wide columns in Python - 2021-02-15
• Using io.BufferedReader to peek against a non-peekable stream - 2021-02-15

zeit-now

• Running a Python ASGI app on Vercel - 2020-04-19

sqlite

• Lag window function in SQLite - 2020-04-19
• Null case comparisons in SQLite - 2020-04-21
• Compile a new sqlite3 binary on Ubuntu - 2020-04-30
• List all columns in a SQLite database - 2020-05-06
• Using LD_PRELOAD to run any version of SQLite with Python - 2020-06-17
• SQLite BLOB literals - 2020-07-29
• Enabling WAL mode for SQLite database files - 2020-08-09
• Compiling the SQLite spellfix.c module on macOS - 2020-09-19
• Figuring out if a text value in SQLite is a valid integer or float - 2020-09-27
• Replicating SQLite with rqlite - 2020-12-28
• Identifying column combination patterns in a SQLite table - 2021-01-12
• Fixing broken text encodings with sqlite-transform and ftfy - 2021-01-18
• Splitting on commas in SQLite - 2021-02-01
• Querying for items stored in UTC that were created on a Thursday in PST - 2021-03-12

presenting

• Using macOS stickies to display a workshop link on the screen - 2020-04-20

macos

• Running pip install -e .[test] in zsh on macOS Catalina - 2020-04-21
• Get Skitch working on Catalina - 2020-04-21
• Close terminal window on Ctrl+D for macOS - 2020-04-21
• Fixing "compinit: insecure directories" error - 2020-04-26
• Finding the largest SQLite files on a Mac - 2020-08-19
• Shrinking PNG files with pngquant and oxipng - 2021-02-07

cloudrun

• Use labels on Cloud Run services for a billing breakdown - 2020-04-21
• How to deploy a folder with a Dockerfile to Cloud Run - 2020-08-04
• Using the gcloud run services list command - 2020-09-01

tailscale

• Restricting SSH connections to devices within a Tailscale network - 2020-04-23

pytest

• Session-scoped temporary directories in pytest - 2020-04-26
• How to mock httpx using pytest-mock - 2020-04-29
• Asserting a dictionary is a subset of another dictionary - 2020-05-28
• Registering temporary pluggy plugins inside tests - 2020-07-21
• Code coverage using pytest and codecov.io - 2020-08-15
• Start a server in a subprocess during a pytest session - 2020-08-31

github

• Accessing repository dependencies in the GitHub GraphQL API - 2020-04-30
• Paginating through the GitHub GraphQL API with Python - 2020-07-09
• Searching for repositories by topic using the GitHub GraphQL API - 2020-10-09
• Bulk fetching repository details with the GitHub GraphQL API - 2021-01-17
• Syntax highlighting Python console examples with GFM - 2021-01-18

node

• Constant-time comparison of strings in Node - 2020-05-01

firefox

• Search across all loaded resources in Firefox - 2020-05-05

markdown

• Converting HTML and rich-text to Markdown - 2020-05-09
• Rendering Markdown with the GitHub Markdown API - 2020-08-22

pypi

• Adding project links to PyPI - 2020-05-11

asgi

• Writing tests for the ASGI lifespan protocol with HTTPX - 2020-06-29

heroku

• Using heroku pg:pull to restore a backup to a macOS laptop - 2020-07-10
• Upgrading a Heroku PostgreSQL database with pg:copy - 2020-07-20
• Programatically accessing Heroku PostgreSQL from GitHub Actions - 2020-08-18

javascript

• Implementing a "copy to clipboard" button - 2020-07-23
• Working around the size limit for nodeValue in the DOM - 2020-08-21
• Dynamically loading multiple assets with a callback - 2020-08-21
• Minifying JavaScript with npx uglify-js - 2020-08-30
• Manipulating query strings with URLSearchParams - 2020-10-04
• Writing JavaScript that responds to media queries - 2020-10-21
• Dropdown menu with details summary - 2020-10-31
• Using Jest without a package.json - 2020-12-30

django

• PostgreSQL full-text search in the Django Admin - 2020-07-25
• Adding extra read-only information to a Django admin change page - 2021-02-25
• Writing tests for the Django admin with pytest-django - 2021-03-02
• Show the timezone for datetimes in the Django admin - 2021-03-02
• Pretty-printing all read-only JSON in the Django admin - 2021-03-07
• How to almost get facet counts in the Django admin - 2021-03-11

docker

• Attaching a bash shell to a running Docker container - 2020-08-10

homebrew

• Packaging a Python CLI tool for Homebrew - 2020-08-11
• Browsing your local git checkout of homebrew-core - 2020-08-27
• Upgrading Python Homebrew packages using pip - 2020-10-14

zsh

• Customizing my zsh prompt - 2020-08-12

readthedocs

• Pointing a custom subdomain at Read the Docs - 2020-08-14
• Read the Docs Search API - 2020-08-16
• Using custom Sphinx templates on Read the Docs - 2020-12-07

ics

• Providing a "subscribe in Google Calendar" link for an ics feed - 2020-08-21

svg

• Creating a dynamic line chart with SVG - 2020-08-22

linux

• Piping echo to a file owned by root using sudo and tee - 2020-08-24
• Basic strace to see what a process is doing - 2020-09-07

jq

• Converting Airtable JSON for use with sqlite-utils using jq - 2020-08-28
• Loading radio.garden into SQLite using jq - 2021-02-17
• Flattening nested JSON objects with jq - 2021-03-11
• Converting no-decimal-point latitudes and longitudes using jq - 2021-03-11

bash

• Looping over comma-separated values in Bash - 2020-09-01
• Escaping strings in Bash using !:q - 2020-10-01
• Escaping a SQL query to use with curl and Datasette - 2020-12-08
• Skipping CSV rows with odd numbers of quotes using ripgrep - 2020-12-11

typescript

• Very basic tsc usage - 2020-09-06

aws

• Display EC2 instance costs per month - 2020-09-06
• Recovering data from AWS Lightsail using EC2 - 2021-01-16

jinja

• Turning on Jinja autoescaping when using Template() directly - 2020-09-18

selenium

• Installing Selenium for Python on macOS with ChromeDriver - 2020-10-02
• Using async/await in JavaScript in Selenium - 2020-10-02

digitalocean

• Running Datasette on DigitalOcean App Platform - 2020-10-06

datasette

• Redirects for Datasette - 2020-11-25
• Serving MBTiles with datasette-media - 2021-02-03
• Querying for GitHub issues open for less than 60 seconds - 2021-03-12

jupyter

• Embedding JavaScript in a Jupyter notebook - 2021-01-22

cookiecutter

• Testing cookiecutter templates with pytest - 2021-01-27
• Conditionally creating directories in cookiecutter - 2021-01-27

gis

• Downloading MapZen elevation tiles - 2021-02-04

sphinx

• Using sphinx.ext.extlinks for issue links - 2021-02-17

postgresql

• Show the SQL schema for a PostgreSQL database - 2021-02-23
• Granting a PostgreSQL user read-only access to some tables - 2021-02-26

mediawiki

• How to run MediaWiki with SQLite on a macOS laptop - 2021-03-06