JSON
Mock Data Generators for JSON Tests Demos and Load
Generate JSON test data with Faker, Hypothesis, SQL and jq: seeds for repeatable runs, collisions, and a property test that found real bugs.
6 min read
Topic
Tooling
Clients, formatters, linters and CLIs worth installing. Small tools that save hours.
JSON
Comparing JSON Ignoring Volatile Fields in Python Tests
Compare JSON documents in tests while ignoring ids and timestamps: strip keys, DeepDiff exclusions, placeholders that keep relations, jq del, float tolerance.
6 min read
JSON
Snapshot Testing JSON Output Without Flaky Failures
Snapshot tests for JSON in pytest with syrupy and Node's test runner: what a snapshot stores, why random ids break it, and matchers and scrubbing that fix it.
6 min read
CSV
Choosing Between csvkit and Miller for Everyday CSV Work
csvkit and Miller timed on the same 200,000-row file. Type inference makes csvkit's sort, stat and JSON commands 100 times slower and can rewrite your dates.
6 min read
CSV
Datasette for Publishing CSV as a Searchable Site in Minutes
Turn a CSV into a browsable, searchable, filterable website with sqlite-utils and Datasette, with a JSON and CSV API, facets and full-text search built in.
7 min read
CSV
Polars for Large CSV Processing Beyond Memory Limits
Use Polars lazy scanning to filter and group a large CSV without loading it whole, set column types so zip codes stay text, and write Parquet as you go.
6 min read
YAML
YAML Anchors Aliases and Merge Keys Without Surprises
Define a block once with an anchor, reuse it with an alias, and merge it with the merge key. Real output shows overrides, sharing and where merging stops.
5 min read
YAML
YAML Lists and Mappings Without Confusion in Real Files
Block and flow styles for sequences and mappings, lists of mappings, empty collections and why a missing value is None, each with its parsed result.
6 min read
YAML
YAML Multiline Strings With Pipe and Greater Than Signs
The pipe keeps line breaks, the greater than sign folds them, and chomping indicators control the final newline. Six variants and the exact strings.
5 min read
YAML
YAML Strings Quoting and When You Really Need Quotes
Plain, single quoted and double quoted YAML strings compared, with the characters that force quotes and a table of values that silently change type.
5 min read
YAML
YAML Indentation Rules and Why Tabs Break Everything
How YAML uses spaces to build structure, why a tab is rejected, and how one extra space turns a sibling into a child. Real parser output for each case.
6 min read
XML
Reading a SOAP Response and Pulling the Fields You Need
Pull records out of a SOAP response with lxml: mixed-namespace children, xsi:nil, empty versus absent, repeated nodes and exact decimals.
6 min read
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