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
Tag
how-to
590 posts
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
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
YAML
Naming Keys Consistently in YAML Config Files Everywhere
Pick one key style, enforce it with a JSON Schema pattern and fix old files with a yq command that renames every key. Real output for each step.
6 min read
CSV
Using the Python csv Module for Reading Files Line by Line
Read CSV in Python with csv.reader: open with newline='', handle quoted commas and multi-line fields, set the dialect, and stream millions of rows.
8 min read
JSON
Building JSON Output With JSON_OBJECT and JSON_ARRAYAGG
Build nested JSON from MySQL tables with JSON_OBJECT and JSON_ARRAYAGG, and handle booleans, ordering, empty results and join fan-out.
7 min read
XML
Disabling DTDs and External Entities in Java and Python
Parser settings that stop XXE in Java and Python, tested on one file: which Java features block it, what each error says, and the lxml options.
7 min read
Editor's pick
CSVGuide
Reading and Writing CSV Files in Python the Right Way
A working guide to CSV in Python: csv module, DictReader, pandas, polars and DuckDB measured on 2,000,000 rows, plus the encoding, quoting and type rules.
22 min read
CSV
Writing Query Results Back Out to CSV With DuckDB COPY
Export a DuckDB query to CSV with COPY. Control the delimiter, NULL text, quoting, date format and compression, and split output into one file per value.
9 min read
YAML
Comments That Help the Next Person Reading Your YAML
What to write in YAML comments, what to leave out and how to lint comment style. Includes yamllint output for spacing and indentation, and what tools drop.
6 min read