github datamodel-code-generator/datamodel-code-generator 0.77.0
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2 hours ago

Breaking Changes

Code Generation Changes

  • Nested Avro bytes and fixed defaults are now decoded to bytes - Avro bytes and fixed defaults nested inside arrays, maps, and records are now converted to Python bytes literals such as b'\xff', whereas previously only top-level bytes and fixed defaults were converted and nested ones remained as strings, so regenerating affected Avro schemas produces different default values across the pydantic v2, dataclass, and msgspec backends (#3896)
  • Dictionary defaults now render as factories for pydantic v2 dataclasses - Fields with a dictionary default now emit Field(default_factory=...) and add a from pydantic import Field import instead of the previous plain default rendering, so regenerating existing schemas produces different output; ClassVar and plain required dictionary fields are additionally kept free of Field statements (#3883)
  • Ruff formatter output changed by pinned ruff upgrade - The pinned ruff dependency was bumped from 0.14.10 to 0.16.6, which changes how generated code is formatted when the ruff formatters are used: blank lines are now inserted between import groups, import statements are regrouped and reordered, and combined aliased imports such as a single line importing several names with an as alias are split onto separate lines, so files regenerated from the same input will differ from output produced by earlier versions (#3874)
  • Avro decimal defaults now emit Decimal values - Avro bytes and fixed fields carrying a decimal logical type with a default now decode the default as a signed big-endian coefficient scaled by the declared scale and emit a Decimal(...) expression for backends that support deserialized defaults, replacing the previous raw bytes literal output, so regenerating existing models yields different default values (#3902)
  • Avro temporal defaults now emit temporal values - For Avro fields with a temporal logical type such as date, time-millis, time-micros, timestamp-millis, timestamp-micros, timestamp-nanos, or the local-timestamp variants, an integer default is now rendered as a temporal constructor like datetime_module.date.fromisoformat or an ISO-8601 string for backends that map these formats to str, instead of the previous raw integer literal, so generated models change for any schema using these defaults; timestamp defaults use UTC while local-timestamp and time defaults are naive (#3901)
  • Avro duration defaults now decode to timedelta - Avro fixed fields using the duration logical type with a default now emit timedelta(milliseconds=N) values instead of the raw bytes previously produced, changing generated output for any schema that relies on such defaults (#3907)
  • XML Schema nillable now recognizes the 1 lexical value - Elements declared with nillable="1" are now treated the same as nillable="true" and generate a nullable field, so schemas that previously produced a required field for nillable="1" will now produce an optional (nullable) field (#3884)
  • Avro unqualified name resolution now prefers the enclosing namespace - When resolving an unqualified Avro reference to a record, enum, or fixed type, the parser previously returned the first matching globally registered name; it now first looks for a matching type in the current enclosing namespace and only falls back to the global name when none exists. For Avro schemas that reuse the same unqualified name in both the null namespace and a nested namespace, generated models now reference the namespaced type instead of the global one, changing the generated output. (#3898)
  • Enum list defaults now preserve unmatched values - Previously, when a field default was a list, only values that matched an enum member were kept and any unmatched entries were silently dropped from the generated default; now unmatched entries such as plain strings, None, nested lists, and dictionaries are retained in place while matching entries are converted to enum members, so generated default lists can differ for the same input (#3887)
  • Multiple enum sources in a union are converted - The generator now inspects every enum branch of a union data type rather than only a single reference, so a value matching any enum member in the union is converted to that member and unmatched values remain literals, changing generated defaults for union-typed fields (#3887)
  • Combined XSD pattern facets change generated regexes - XML Schema restrictions with multiple sibling xs:pattern facets previously kept only the last pattern value, and now the parser merges all supported sibling patterns into a single anchored alternation and intersects any inherited base pattern through a nested lookahead, so regenerating from such schemas produces different pattern strings than before (#3908)
  • Pydantic outputs gain a python-re engine setting - Pydantic model output for these combined-pattern types now emits a regex_engine="python-re" configuration entry that was not present before, because the generated anchored lookahead requires Pydantic's Python regex engine, changing the generated model configuration for affected fields (#3908)
  • Type-alias defaults for msgspec Struct now build real Struct instances - When generating msgspec Struct models with type aliases enabled, a field whose default is an object or array and whose declared type is an alias that resolves through chained aliases or unions to a Struct model now emits a default factory that calls convert to construct the referenced Struct instance, whereas previously such defaults were emitted as plain literal values because only direct Struct references were converted; empty collections, mapping and dict defaults, primitive aliases, and recursive non-model aliases keep their prior output (#3906)

Error Handling Changes

  • Referenced boolean false definitions now rejected - MCP tool input or output schemas that reference a definition whose value is the boolean false now raise an Error reading "Referenced MCP boolean false definition is not supported" instead of emitting a permissive model, so schemas that previously generated code may now fail during conversion (#3890)
  • Invalid Avro decimal defaults now raise errors - Decimal defaults whose scale falls outside Python's Decimal range, whose coefficient exceeds the declared precision, or whose fixed encoding length does not match the declared size now raise an error during generation instead of being emitted, so schemas that previously generated successfully may now fail (#3902)
  • Unrepresentable Avro temporal defaults now raise errors - Temporal defaults outside the Python date or datetime range, time defaults not within a single day, and nanosecond defaults that cannot be represented exactly at microsecond precision now raise an error and abort generation, whereas these schemas previously generated successfully by emitting the raw integer default (#3901)
  • Avro duration defaults with calendar components or wrong size now error - Duration defaults with nonzero months or days, or that are not encoded as exactly 12 bytes with a fixed size of 12, now raise an error during generation instead of decoding to bytes (#3907)

Default Behavior Changes

  • RootModel metadata now reports the field name and alias as root - When emitting model metadata for RootModel classes, the emitted field entry now uses root for both its name and alias instead of the previously emitted synthetic field name, so consumers of the emitted metadata for root models will see different name and alias values (#3897)
  • Dynamic extraction now returns root-model type aliases - The generate_dynamic_models runtime helper now includes specialized RootModel type-alias classes that are assigned at the top level of the generated code, whereas it previously omitted any class whose defining module was not the generated module, so existing callers receive additional entries in the returned mapping while genuine imported dependencies remain excluded (#3904)

What's Changed

Full Changelog: 0.76.2...0.77.0

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