Settings¶

Set options on a YAML() instance. Defaults preserve the layout of loaded documents; use formatting options when you create new content.

Indent a new document¶

from yamluna import YAML

yaml = YAML()
yaml.indent(mapping=2, sequence=4, offset=2)
print(yaml.dump({'ports': [80, 443]}), end='')

Output:

ports:
  - 80
  - 443

For existing files, leave indent() unset to keep their indentation. Applying it to some loaded lists can change their layout or produce invalid output; see limitations.

Add document markers¶

from yamluna import YAML

yaml = YAML()
yaml.explicit_start = True
yaml.explicit_end = True
print(yaml.dump({'ready': True}), end='')

Output:

---
ready: true
...

For these two settings, None keeps the original markers, True adds them, and False removes them.

Options you may need¶

Setting	Default	Effect
`preserve_quotes`	`None`	Set `True` for editing or creating quoted strings
`default_flow_style`	`False`	Set `True` to use inline collections such as `{ready: true}`, including loaded collections
`width`	`None` (80 columns)	Preferred wrapping width for newly formatted text; unchanged text keeps its wrapping
`explicit_start` / `explicit_end`	`None`	Control `---` / `...` markers
`line_break`	`None`	Set `'\n'`, `'\r\n'`, or `'\r'` explicitly
`encoding`	`'utf-8'`	Encoding for files and binary output streams
`allow_duplicate_keys`	`False`	Set `True` to warn and keep the last value of a repeated key
`version`	`None`	Set `(1, 2)` or `(1, 1)` to write a YAML version directive

version controls output. Input declaring %YAML 1.1 uses YAML 1.1 rules for booleans and octal numbers; input without a directive uses YAML 1.2 rules.

For Windows-style line endings, set yaml.line_break = '\r\n'. Automatic detection does not preserve them in every file.

For per-value formatting, use string types or node.fa.set_flow_style() / node.fa.set_block_style() on a collection.