XMLGuide
Parsing and Writing XML in Python With ElementTree and lxml
A tested guide to XML in Python: ElementTree versus lxml, reading, streaming, writing, namespaces, validation, XSLT, tables, safety and an end-to-end script.
18 min read
Tag
how-to
590 posts
CSV
Using COPY to Load a CSV File Into a PostgreSQL Table
The COPY command in practice: the options that matter, the two ways to feed it, what its row count means, and why one bad value undoes the whole load.
7 min read
Editor's pick
CSVGuide
How to Load a CSV File Into PostgreSQL Without Losing Rows
Load a CSV into PostgreSQL with COPY, see what makes it fast, and learn what each failure means, with a script that loads in one transaction.
20 min read
XMLGuide
XPath Queries That Cover Most Real Needs in XML Work
A tested XPath guide: the twenty expressions that cover most needs, the traps (namespaces, positions, units, injection), tools, timings on 200,000 records.
18 min read
CSV
Handling Emoji in CSV Imports Without Losing Characters
MySQL utf8 columns hold three bytes per character, so an emoji becomes a question mark during a CSV load with only a warning. See the fix and the checks.
7 min read
PostgreSQLGuide
Getting Fast With psql and Habits That Save Hours a Week
Get fast with psql: meta commands, a psqlrc, expanded output and pagers, scripts, variables, timing, editor integration, output to files and pgpass.
18 min read
ExcelGuide
Sending Database Results to Excel Properly Every Time
Export SQL results to Excel that open cleanly: keep types and dates, carry formatting, use several sheets, resist formula injection and run on a schedule.
18 min read
JSON
Python JSONDecodeError Extra Data and Concatenated Objects
Extra data means a valid JSON value was followed by more text. Why concatenated objects and JSON Lines trigger it and three ways to read them in Python.
7 min read
CSV
Converting a CSV From Latin 1 or Windows 1252 to UTF8
Convert a legacy CSV to UTF-8 with iconv or Python, choose between Latin 1 and Windows 1252, and handle the five bytes Windows 1252 leaves undefined.
7 min read
CSV
The UTF8 BOM in CSV Files and When It Helps or Hurts
Three invisible bytes at the start of a CSV can fix Excel or break a header match. See which readers strip a BOM and how to add or remove one.
7 min read
JSON
Python JSONDecodeError Expecting Value Line 1 Column 1
Why json.loads or response.json() raises Expecting value at line 1 column 1 in Python, how to see what the text really is, and a checklist for each cause.
7 min read
XML
Python ParseError Unbound Prefix in XML and How to Fix It
Fix ElementTree ParseError unbound prefix and lxml Namespace prefix is not defined: fragments cut from a document, auto-declared prefixes, recover.
7 min read