Add list constraints (#27)

* add list constraints

* add more testcases

src/drf_pydantic/parse.py

@@ -11,6 +11,7 @@
 import pydantic.fields
 import pydantic_core
 
+from annotated_types import MaxLen, MinLen
 from pydantic._internal._fields import PydanticMetadata
 from rest_framework import serializers  # type: ignore
 from typing_extensions import TypeAliasType
@@ -165,6 +166,24 @@ def _convert_field(field: pydantic.fields.FieldInfo) -> serializers.Field:
                 if item.max_length is not None
                 else drf_field_kwargs.get("max_length", None)
             )
+        elif isinstance(item, MinLen):
+            drf_field_kwargs["min_length"] = (
+                max(
+                    drf_field_kwargs.get("min_length", float("-inf")),
+                    item.min_length,
+                )
+                if item.min_length is not None
+                else drf_field_kwargs.get("min_length", None)
+            )
+        elif isinstance(item, MaxLen):
+            drf_field_kwargs["max_length"] = (
+                min(
+                    drf_field_kwargs.get("max_length", float("inf")),
+                    item.max_length,
+                )
+                if item.max_length is not None
+                else drf_field_kwargs.get("max_length", None)
+            )
         # pydantic.Field constraints
         elif isinstance(item, PydanticMetadata):
             # Decimal constraints

tests/test_fields.py

@@ -45,6 +45,25 @@ class Person(BaseModel):
         assert serializer.fields["name"].min_length == 3
         assert serializer.fields["name"].max_length == 10
 
+    def test_constrained_string_defined_from_field(self):
+        class Person(BaseModel):
+            name: str = pydantic.Field(min_length=3, max_length=10)
+
+        serializer = Person.drf_serializer()
+
+        assert isinstance(serializer.fields["name"], serializers.CharField)
+        assert serializer.fields["name"].min_length == 3
+        assert serializer.fields["name"].max_length == 10
+
+    def test_constrained_list(self):
+        class Person(BaseModel):
+            name: list[int] = pydantic.Field(min_length=3, max_length=10)
+
+        serializer = Person.drf_serializer()
+        assert isinstance(serializer.fields["name"], serializers.ListField)
+        assert serializer.fields["name"].min_length == 3
+        assert serializer.fields["name"].max_length == 10
+
     def test_email(self):
         class Person(BaseModel):
             email: pydantic.EmailStr