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fix: OpenAPI schema missing minItems/maxItems for msgspec Meta on collections #4605

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fix: OpenAPI schema missing minItems/maxItems for msgspec Meta on collections #4605

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b52da33
Fix OpenAPI schema missing minItems/maxItems for msgspec collection f…
worksbyfriday Feb 22, 2026
ebde883
Move msgspec.Meta handling out of _annotated_types_extractor
worksbyfriday Feb 22, 2026
5983ddd
Merge collection test into existing msgspec annotated type test
worksbyfriday Feb 23, 2026
b834398
Fix msgspec Struct field ordering in test
worksbyfriday Feb 27, 2026
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11 changes: 11 additions & 0 deletions litestar/plugins/core/_msgspec.py
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,17 @@ def kwarg_definition_from_field(field: msgspec.inspect.Field) -> tuple[Parameter
kwargs["max_length"] = field_type.max_length
if isinstance(field_type, msgspec.inspect.StrType):
kwargs["pattern"] = field_type.pattern
elif isinstance(
field_type,
(
msgspec.inspect.ListType,
msgspec.inspect.SetType,
msgspec.inspect.FrozenSetType,
msgspec.inspect.VarTupleType,
),
):
kwargs["min_items"] = field_type.min_length
kwargs["max_items"] = field_type.max_length

parameter_defaults = {
f.name: default for f in dataclasses.fields(ParameterKwarg) if (default := f.default) is not dataclasses.MISSING
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9 changes: 8 additions & 1 deletion tests/unit/test_openapi/test_schema.py
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Original file line number Diff line number Diff line change
Expand Up @@ -294,13 +294,17 @@ class Foo(TypedDict):


def test_create_schema_from_msgspec_annotated_type() -> None:
from uuid import UUID

class Lookup(msgspec.Struct):
int_field: Annotated[int, msgspec.Meta(gt=0)]
str_field: Annotated[
str,
msgspec.Meta(max_length=16, examples=["example"], description="description", title="title", pattern=r"\w+"),
]
bytes_field: Annotated[bytes, msgspec.Meta(max_length=2, min_length=1)]
list_field: Annotated[list[UUID], msgspec.Meta(min_length=1, max_length=10)]
set_field: Annotated[set[int], msgspec.Meta(min_length=2)]
default_field: Annotated[str, msgspec.Meta(min_length=1)] = "a"

schema = get_schema_for_field_definition(FieldDefinition.from_kwarg(name="Lookup", annotation=Lookup))
Expand All @@ -312,13 +316,16 @@ class Lookup(msgspec.Struct):
assert schema.properties["str_field"].description == "description" # type: ignore[index]
assert schema.properties["str_field"].title == "title" # type: ignore[index, union-attr]
assert schema.properties["str_field"].max_length == 16 # type: ignore[index, union-attr]
assert sorted(schema.required) == sorted(["int_field", "str_field", "bytes_field"]) # type: ignore[arg-type]
assert sorted(schema.required) == sorted(["int_field", "str_field", "bytes_field", "list_field", "set_field"]) # type: ignore[arg-type]
assert schema.properties["bytes_field"].to_schema() == { # type: ignore[index]
"contentEncoding": "utf-8",
"maxLength": 2,
"minLength": 1,
"type": "string",
}
assert schema.properties["list_field"].min_items == 1 # type: ignore[index, union-attr]
assert schema.properties["list_field"].max_items == 10 # type: ignore[index, union-attr]
assert schema.properties["set_field"].min_items == 2 # type: ignore[index, union-attr]


def test_annotated_types() -> None:
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