Options

Options are integer bit flags. Combine them with the bitwise-OR operator | and pass the result as option:

import yamlrocks

yamlrocks.dumps({"b": 1, "a": 2}, option=yamlrocks.OPT_SORT_KEYS | yamlrocks.OPT_INDENT_4)
# b'a: 2\nb: 1\n'

A flag that does not apply to a given call is ignored, so it is safe to keep a single option constant and reuse it across loads and dumps.

Parsing

These flags change how loads, loads_all, load, and load_all interpret a document.

Flag	Effect
OPT_YAML_1_1	Use the YAML 1.1 schema: yes/no/on/off booleans (and bare y/n, per the spec), 0777 octals, and sexagesimal numbers.
OPT_PYYAML_COMPAT	Use PyYAML’s deliberately off-spec boolean set: yes/no/on/off/true/false but not bare y/n (they stay strings). Implies the 1.1 schema; matches the PyYAML ecosystem.
OPT_ROUND_TRIP	Return a YAMLRocksDocument preserving comments, anchors, and formatting.
OPT_ANNOTATED	Return dict/list/str subclasses carrying source line and column.
OPT_ANNOTATE_NUMBERS	With OPT_ANNOTATED, also annotate int/float (as YAMLRocksAnnotatedInt/Float) so numbers carry a source location. Off by default; makes type(x) is int false. bool/None stay plain.
OPT_REJECT_COMPLEX_KEYS	Reject a collection (sequence or mapping) used as a mapping key, raising YAMLRocksComplexKeyError with a location, instead of converting it to a tuple (a mapping key becomes a tuple of its pairs). Off by default (accept-and-convert is spec-compliant). For scalar-keyed consumers; catches the unquoted-template typo early.
OPT_INCLUDES	Resolve the !include family of tags. Needs include_dir, or use load() so includes resolve next to the file.
OPT_INCLUDE_DIR_RECURSIVE	Make the !include_dir_* tags descend into subdirectories (os.walk-style); off by default (top level only).
OPT_SECRETS	Resolve !secret name against a secrets.yaml, searching up to the config root. Needs include_dir, or use load().
OPT_SECRET_NOT_FOUND_WARN	Downgrade an undefined !secret from a hard error to a logged WARNING that resolves to None, so one pass reports every miss. Off by default (loading stays fail-fast); needs OPT_SECRETS. For a structured per-miss callback, see on_missing_secret.
OPT_ENV_VAR	Resolve !env_var NAME [default] against the process environment.
OPT_ENV_VAR_NOT_FOUND_WARN	Downgrade a bare undefined !env_var (no default) from a hard error to a logged WARNING that resolves to None, so one pass reports every miss. Off by default; needs OPT_ENV_VAR. For a structured per-miss callback, see on_missing_env_var.
OPT_UPGRADE_1_1	Read as YAML 1.1 but always emit canonical 1.2, a bridge for easing into 1.2.
OPT_YAML_1_1_WARN	Log (on the yamlrocks logger) each scalar that resolves to a different type under 1.1 than 1.2, a migration aid. Pair with OPT_YAML_1_1 or OPT_UPGRADE_1_1; a no-op without them.
OPT_PASSTHROUGH_TAG	Surface custom-tagged values as YAMLRocksTag objects instead of dropping the tag.
OPT_DUPLICATE_KEYS_ERROR	Raise YAMLRocksDecodeError on a repeated mapping key (default: last wins). The merge key << is exempt.
OPT_DUPLICATE_KEYS_WARN	Log a repeated mapping key on the yamlrocks logger (WARNING) but keep the last value. Ignored when OPT_DUPLICATE_KEYS_ERROR is also set.

By default yes is a plain string in YAML 1.2; OPT_YAML_1_1 switches to the older schema where it is a boolean:

import yamlrocks

yamlrocks.loads(b"a: yes")                              # {'a': 'yes'}
yamlrocks.loads(b"a: yes", option=yamlrocks.OPT_YAML_1_1)  # {'a': True}

OPT_DUPLICATE_KEYS_ERROR rejects a repeated key with the offending location in the message:

import yamlrocks

source = """
a: 1
a: 2
"""

yamlrocks.loads(source, option=yamlrocks.OPT_DUPLICATE_KEYS_ERROR)
# yamlrocks.YAMLRocksDecodeError: duplicate mapping key: a at line 2, column 1

For a non-fatal middle ground, OPT_DUPLICATE_KEYS_WARN keeps the last value but logs each duplicate on the yamlrocks logger, so you can surface them through your existing logging configuration without catching an exception:

import logging
import yamlrocks

source = """
a: 1
a: 2
"""

logging.getLogger("yamlrocks")  # configure/route as you like
yamlrocks.loads(source, option=yamlrocks.OPT_DUPLICATE_KEYS_WARN)
# logs WARNING "duplicate mapping key 'a' ...", returns {'a': 2}

When moving a YAML 1.1 codebase to 1.2, OPT_YAML_1_1_WARN (alongside OPT_YAML_1_1 or OPT_UPGRADE_1_1) logs every scalar that the two schemas type differently, so you can find each yes/no boolean, 0777 octal, or sexagesimal that would silently become a plain string under 1.2:

import yamlrocks

source = """
enabled: yes
mask: 0777
"""

yamlrocks.loads(
    source,
    option=yamlrocks.OPT_YAML_1_1 | yamlrocks.OPT_YAML_1_1_WARN,
)
# logs "YAML 1.1 syntax 'yes' resolves as bool in 1.1 but str in 1.2 ..." (and 0777)

Emitting

These flags change how dumps and dump format output. Indentation defaults to two spaces.

Flag	Effect
OPT_INDENT_2	Two-space indentation (the default).
OPT_INDENT_4	Four-space indentation.
OPT_SORT_KEYS	Sort mapping keys alphabetically.
OPT_FLOW_STYLE	Emit flow style ({} / []) instead of block style.
OPT_SINGLE_QUOTES	Use single quotes when quoting, instead of the default double.
OPT_INDENTLESS_SEQUENCES	Align a sequence’s dashes with its key instead of indenting.
OPT_EXPLICIT_START	Emit a --- document-start marker.
OPT_EXPLICIT_END	Emit a ... document-end marker.
OPT_NULL_AS_KEYWORD	Emit None as the explicit null keyword instead of blank.
OPT_NULL_AS_TILDE	Emit None as the ~ indicator instead of blank.

import yamlrocks

yamlrocks.dumps({"a": [1, 2]}, option=yamlrocks.OPT_FLOW_STYLE)
# b'{a: [1, 2]}\n'

yamlrocks.dumps({"a": 1}, option=yamlrocks.OPT_EXPLICIT_START | yamlrocks.OPT_EXPLICIT_END)
# b'---\na: 1\n...\n'

Null style

When dumps serializes None, it leaves the value blank by default (key:), matching the dominant real-world configuration style. OPT_NULL_AS_KEYWORD switches the default to the explicit null keyword and OPT_NULL_AS_TILDE to ~; the two flags are mutually exclusive (setting both raises ValueError). The per-call null_style argument of dumps/dump overrides the flag for one call. The accepted styles are "null", "empty", and "~". All three parse back to None, so the choice is purely cosmetic.

The blank form is used only where it reads back unambiguously as null: a block mapping value (key:) or a block sequence entry (-). At the top level, inside a flow collection, or as a mapping key it falls back to null, so the output is always valid YAML 1.2. The ~ form is unambiguous everywhere and is used as-is.

import yamlrocks

yamlrocks.dumps({"a": None})
# b'a:\n'

yamlrocks.dumps({"a": None}, null_style="null")
# b'a: null\n'

yamlrocks.dumps({"a": None}, null_style="~")
# b'a: ~\n'

# The argument overrides the flag for one call.
yamlrocks.dumps({"a": None}, option=yamlrocks.OPT_NULL_AS_KEYWORD, null_style="empty")
# b'a:\n'

Round-trip editing

The same default applies when you edit a round-trip YAMLRocksDocument and assign None to a key: it re-emits as a blank value (key:). OPT_NULL_AS_KEYWORD or OPT_NULL_AS_TILDE at load time switches assigned nulls to null or ~. A null that was already in the file keeps its original form, so an untouched value always re-emits byte-for-byte.

import yamlrocks

doc = yamlrocks.loads(b"x: 1\n", option=yamlrocks.OPT_ROUND_TRIP)
doc["x"] = None
doc.to_yaml()
# b'x:\n'

Type serialization

These flags control how dumps renders standard-library values.

Flag	Effect
OPT_SERIALIZE_NUMPY	Serialize numpy arrays and scalars (off by default; without it they raise YAMLRocksEncodeError).
OPT_OMIT_MICROSECONDS	Drop the microsecond field from datetime and time.
OPT_NAIVE_UTC	Treat a naive datetime as UTC, appending a +00:00 offset.
OPT_UTC_Z	Render a +00:00 UTC offset as Z.
OPT_PASSTHROUGH_DATETIME	Do not auto-serialize datetime/date/time; route them to default.
OPT_PASSTHROUGH_DATACLASS	Do not auto-serialize dataclass instances; route them to default.

The datetime flags compose. A UTC datetime renders in full ISO 8601 by default; combine OPT_OMIT_MICROSECONDS and OPT_UTC_Z for the compact form:

import datetime
import yamlrocks

dt = datetime.datetime(2026, 6, 5, 12, 30, 45, 123456, tzinfo=datetime.timezone.utc)

yamlrocks.dumps(dt)
# b'2026-06-05T12:30:45.123456+00:00\n'

yamlrocks.dumps(dt, option=yamlrocks.OPT_OMIT_MICROSECONDS | yamlrocks.OPT_UTC_Z)
# b'2026-06-05T12:30:45Z\n'

The passthrough flags hand a value to your default callback instead of using the built-in renderer, so you can emit a custom format:

import datetime
import yamlrocks

def default(obj):
    if isinstance(obj, datetime.datetime):
        return obj.strftime("%Y/%m/%d")
    raise TypeError

yamlrocks.dumps(
    {"when": datetime.datetime(2026, 6, 5)},
    default=default,
    option=yamlrocks.OPT_PASSTHROUGH_DATETIME,
)
# b'when: 2026/06/05\n'

See also

• API reference: the functions these flags configure.
• Dumping: emit styles and the default hook.
• YAML 1.1 vs 1.2: what OPT_YAML_1_1 changes.