Library

Everything you need to level up your coding skills.

YAML

Environment Variable Substitution in YAML Config Files

Substitute environment variables into YAML config after parsing, not before. Expanding text first broke on a colon and hash; a typed walk kept the value.

6 min read

YAML

Reading YAML Front Matter From Markdown Files in Python

Split a Markdown file into YAML metadata and body with one regex, then handle dates, CRLF, a BOM, a missing closing line and body text with dashes.

6 min read

YAML

Merging Two YAML Files in Python With a Deep Merge

dict update is shallow and replaces whole blocks. A 10-line deep merge, the list policy choice and what null means, tested on a base and an override file.

6 min read

YAML

Diffing YAML Files Without Whitespace Noise or Reordering

diff -w hides YAML indentation changes that alter meaning. Normalize both files with yq sort_keys and compare as data to ignore layout and order only.

6 min read

YAML

Merging YAML Files From the Command Line With yq Safely

Deep-merge a base and an override with yq eval-all, choose whether lists replace or append, and check what a null or an empty value in the override does.

6 min read

YAML

Validating YAML Configuration With pydantic Models

Load YAML, validate it with pydantic models and get every error with its path. The Norway problem caught, extra keys rejected and ranges enforced.

7 min read

YAML

Loading Multiple Documents From One YAML File in Python

A YAML file can hold several documents separated by three dashes. safe_load fails on them, safe_load_all reads them and safe_dump_all writes them.

6 min read

YAML

Preserving Comments and Order With ruamel yaml Round Trips

Edit a YAML file from Python and keep its comments, key order, quotes and block strings with ruamel.yaml round-trip mode, plus settings and caveats.

7 min read

JSON

Converting YAML to JSON for Tools That Need It Safely

Convert YAML to JSON with PyYAML and ruamel.yaml, and handle dates, yes and no, octal numbers, non-string keys, anchors, multiple documents and floats.

8 min read

JSON

Converting JSON to YAML on the Command Line Safely

Convert JSON to YAML with yq, Python's yq and a PyYAML one-liner, and see which strings get corrupted by YAML 1.1 readers: NO, yes, 12:30, 0123 and 1e3.

7 min read

YAML

Writing YAML From Python Without Ugly Output or Surprises

PyYAML safe_dump sorts keys, escapes Unicode and quotes multiline strings with blank lines. The options and a block-string representer that fix each default.

6 min read

YAML

Loading YAML in Python With PyYAML safe_load Explained

What yaml.safe_load returns, how to open files correctly, why the C loader is six times faster and the type surprises that come with PyYAML.

6 min read

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