CSV
pandas read_csv Dtype Warnings and How to Fix Them
What DtypeWarning mixed types means in pandas read_csv, how it splits one column into ints and strings, and three ways to fix it, with counts.
7 min read
Library
Everything you need to level up your coding skills.
YAML
Reviewing YAML Config Changes in a Pull Request Safely
A two-line YAML diff can move a key to another level or turn a string into a float. Review the loaded data, not the text, with a short script and a linter.
7 min read
Excel
Fixing Circular Reference Warnings in Imported Sheets
Why imported Excel sheets warn about circular references, how to find the loop with the trace tools, and the fix for each cause in formulas and scripts.
7 min read
JSON
Validating JSON Before It Gets Into a MySQL Column
Enforce structure on a MySQL JSON column with JSON_TYPE checks and JSON_SCHEMA_VALID in CHECK constraints, with the draft 4 limits and the insert cost.
8 min read
CSV
Using pandas read_csv for Files That Do Not Behave
Make pandas read_csv cope with title lines, comments, European numbers, odd NA markers, short or long rows and the wrong encoding, one option at a time.
9 min read
XML
XML Signature Wrapping in Plain Language With a Toy Example
Signature wrapping moves a signed element so the signature verifies while the app reads another. A toy HMAC example shows the gap and the fix.
6 min read
Excel
Excel Formula Shows as Text Instead of Calculating
Fix an Excel formula that shows as text instead of a result: Text format, Show Formulas, a leading apostrophe, manual calculation and scripts.
7 min read
CSV
Writing a CSV File With Python and Keeping Quotes Correct
Write CSV in Python with csv.writer and DictWriter: newline='', the quoting modes, how None, floats, dates and bytes are written, and what Excel needs.
9 min read
JSON
MySQL JSON Versus MariaDB JSON and the Differences
MariaDB's JSON is validated text and MySQL's is a binary type. What differs in storage, operators, indexes, errors and speed, measured on 200,000 rows.
8 min read
Excel
Fixing BadZipFile When Reading an XLSX With Python
Fix zipfile.BadZipFile File is not a zip file when openpyxl or pandas reads an xlsx: wrong content, empty or truncated file, encryption and upload mistakes.
7 min read
CSV
Reading a CSV Into Dictionaries With csv DictReader
csv.DictReader turns each CSV row into a dict keyed by the header. See what it does with missing and extra fields, BOMs, duplicate headers and blank lines.
9 min read
XML
Safe XML Handling in PHP and Node for Untrusted Input
Parse untrusted XML in PHP 8.5 and Node 24: why LIBXML_NOENT is the dangerous flag, what DOMDocument does, and how two Node parsers behave.
6 min read
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