YAML
YAML Error Could Not Find Expected Colon and Its Causes
A line with a word and no colon makes the parser fail while scanning a simple key. See the message in three parsers, the usual causes and the fixes.
6 min read
Tag
beginner
54 posts
YAML
YAML Error Did Not Find Expected Key and How to Fix It
Why a line indented between two levels raises did not find expected key, how PyYAML words it differently, and how to realign. Output from three parsers.
6 min read
YAML
YAML Error Found Character That Cannot Start Any Token
Which characters trigger this scanner error, a tab, at sign, backtick or percent sign, what each looks like in output and the fix that clears it.
6 min read
CSV
A Cheat Sheet of CSV Edge Cases to Test Every Parser With
Thirty six tiny CSV files that separate good readers from bad ones, with the right answer for each and the readers that missed it in my tests.
8 min read
YAML
YAML Error Mapping Values Are Not Allowed Here Fixed
What mapping values are not allowed here means, three causes found in real files, an unquoted colon, a stray space and a double value, and the fix for each.
6 min read
CSV
TSV Versus CSV and When Tabs Are the Saner Choice for Data
TSV avoids most quoting because tabs rarely appear in text, but there are three TSV dialects and they disagree. See where each breaks and which to pick.
7 min read
CSV
How to Escape Quotes and Newlines Inside CSV Fields
Write CSV that survives every reader. Wrap fields with commas, quotes or line breaks, double inner quotes, and round trip test it against four readers.
9 min read
CSV
Why a CSV File Has No Types and What That Costs You
A CSV stores text, so every reader infers types. Measure what inference costs in time and memory on 2 million rows, and what it breaks: ZIP codes and dates.
8 min read
CSV
How to Tell What Delimiter an Unknown CSV File Uses
Find a file's delimiter in four steps, from looking at the bytes to a quote aware check, and see where Python, DuckDB and qsv sniffers disagree.
9 min read
PostgreSQLGuide
Setting Up PostgreSQL for Development Without Fighting It
Set up PostgreSQL for development: choose native or Docker, pick a version, create a user, connect, find the config files and fix common errors.
18 min read
CSV
Does a CSV File Need a Header Row and What If It Has None
A CSV has no flag that says whether row one is a header, so readers guess. Test four files, set the header explicitly, and handle duplicate names.
8 min read
CSV
CSV Line Endings and the CR LF Trap in Shells and Loaders
A CSV from Windows leaves an invisible carriage return on every last column. See it in a shell loop and MySQL, and fix it without damaging quoted fields.
8 min read