OpenAPITools · timonrieger · Feb 9, 2026 · Feb 9, 2026 · Feb 9, 2026
diff --git a/modules/openapi-generator/src/main/resources/python-fastapi/model_generic.mustache b/modules/openapi-generator/src/main/resources/python-fastapi/model_generic.mustache
@@ -81,7 +81,8 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
 {{/vars}}
 
     model_config = {
-        "populate_by_name": True,
+        "validate_by_name": True,
+        "validate_by_alias": True,
         "validate_assignment": True,
         "protected_namespaces": (),
     }

diff --git a/modules/openapi-generator/src/main/resources/python/README_onlypackage.mustache b/modules/openapi-generator/src/main/resources/python/README_onlypackage.mustache
@@ -39,7 +39,7 @@ To be able to use it, you will need these dependencies in your own package that
 * pem >= 19.3.0
 * pycryptodome >= 3.9.0
 {{/hasHttpSignatureMethods}}
-* pydantic >= 2
+* pydantic >= 2.11
 * typing-extensions >= 4.7.1
 
 ## Getting Started

diff --git a/modules/openapi-generator/src/main/resources/python/model_generic.mustache b/modules/openapi-generator/src/main/resources/python/model_generic.mustache
@@ -94,7 +94,8 @@ class {{classname}}({{#parent}}{{{.}}}{{/parent}}{{^parent}}BaseModel{{/parent}}
 {{/vars}}
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/modules/openapi-generator/src/main/resources/python/pyproject.mustache b/modules/openapi-generator/src/main/resources/python/pyproject.mustache
@@ -51,7 +51,7 @@ tornado = ">=4.2, <5"
 pem = ">= 19.3.0"
 pycryptodome = ">= 3.9.0"
 {{/hasHttpSignatureMethods}}
-pydantic = ">= 2"
+pydantic = ">= 2.11"
 typing-extensions = ">= 4.7.1"
 {{#lazyImports}}
 lazy-imports = ">= 1, < 2"

diff --git a/modules/openapi-generator/src/main/resources/python/requirements.mustache b/modules/openapi-generator/src/main/resources/python/requirements.mustache
@@ -16,7 +16,7 @@ tornado = ">= 4.2, < 5"
 pem >= 19.3.0
 pycryptodome >= 3.9.0
 {{/hasHttpSignatureMethods}}
-pydantic >= 2
+pydantic >= 2.11
 typing-extensions >= 4.7.1
 {{#lazyImports}}
 lazy-imports >= 1, < 2

diff --git a/modules/openapi-generator/src/main/resources/python/setup.mustache b/modules/openapi-generator/src/main/resources/python/setup.mustache
@@ -33,7 +33,7 @@ REQUIRES = [
     "pem >= 19.3.0",
     "pycryptodome >= 3.9.0",
 {{/hasHttpSignatureMethods}}
-    "pydantic >= 2",
+    "pydantic >= 2.11",
     "typing-extensions >= 4.7.1",
 {{#lazyImports}}
     "lazy-imports >= 1, < 2",

diff --git a/...nt/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/bird.py b/...nt/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/bird.py
@@ -32,7 +32,8 @@ class Bird(BaseModel):
     __properties: ClassVar[List[str]] = ["size", "color"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...cho_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/category.py b/...cho_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/category.py
@@ -32,7 +32,8 @@ class Category(BaseModel):
     __properties: ClassVar[List[str]] = ["id", "name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...o_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/data_query.py b/...o_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/data_query.py
@@ -35,7 +35,8 @@ class DataQuery(Query):
     __properties: ClassVar[List[str]] = ["id", "outcomes", "suffix", "text", "date"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...pi/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/default_value.py b/...pi/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/default_value.py
@@ -50,7 +50,8 @@ def array_string_enum_default_validate_enum(cls, value):
         return value
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/number_properties_only.py b/...-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/number_properties_only.py
@@ -34,7 +34,8 @@ class NumberPropertiesOnly(BaseModel):
     __properties: ClassVar[List[str]] = ["number", "float", "double"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...ent/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/pet.py b/...ent/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/pet.py
@@ -48,7 +48,8 @@ def status_validate_enum(cls, value):
         return value
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...t/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/query.py b/...t/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/query.py
@@ -43,7 +43,8 @@ def outcomes_validate_enum(cls, value):
         return value
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...ent/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/tag.py b/...ent/echo_api/python-disallowAdditionalPropertiesIfNotPresent/openapi_client/models/tag.py
@@ -32,7 +32,8 @@ class Tag(BaseModel):
     __properties: ClassVar[List[str]] = ["id", "name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...PropertiesIfNotPresent/openapi_client/models/test_form_object_multipart_request_marker.py b/...PropertiesIfNotPresent/openapi_client/models/test_form_object_multipart_request_marker.py
@@ -31,7 +31,8 @@ class TestFormObjectMultipartRequestMarker(BaseModel):
     __properties: ClassVar[List[str]] = ["name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/.../models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.py b/.../models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.py
@@ -34,7 +34,8 @@ class TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter(BaseMod
     __properties: ClassVar[List[str]] = ["size", "color", "id", "name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...i_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.py b/...i_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.py
@@ -31,7 +31,8 @@ class TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter(BaseModel):
     __properties: ClassVar[List[str]] = ["values"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/requirements.txt b/samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/requirements.txt
@@ -1,4 +1,4 @@
 urllib3 >= 2.1.0, < 3.0.0
 python_dateutil >= 2.8.2
-pydantic >= 2
+pydantic >= 2.11
 typing-extensions >= 4.7.1
diff --git a/samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/setup.py b/samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/setup.py
@@ -27,7 +27,7 @@
 REQUIRES = [
     "urllib3 >= 2.1.0, < 3.0.0",
     "python-dateutil >= 2.8.2",
-    "pydantic >= 2",
+    "pydantic >= 2.11",
     "typing-extensions >= 4.7.1",
 ]
 

diff --git a/samples/client/echo_api/python/openapi_client/models/bird.py b/samples/client/echo_api/python/openapi_client/models/bird.py
@@ -32,7 +32,8 @@ class Bird(BaseModel):
     __properties: ClassVar[List[str]] = ["size", "color"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/client/echo_api/python/openapi_client/models/category.py b/samples/client/echo_api/python/openapi_client/models/category.py
@@ -32,7 +32,8 @@ class Category(BaseModel):
     __properties: ClassVar[List[str]] = ["id", "name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/client/echo_api/python/openapi_client/models/data_query.py b/samples/client/echo_api/python/openapi_client/models/data_query.py
@@ -35,7 +35,8 @@ class DataQuery(Query):
     __properties: ClassVar[List[str]] = ["id", "outcomes", "suffix", "text", "date"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/client/echo_api/python/openapi_client/models/default_value.py b/samples/client/echo_api/python/openapi_client/models/default_value.py
@@ -50,7 +50,8 @@ def array_string_enum_default_validate_enum(cls, value):
         return value
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/client/echo_api/python/openapi_client/models/number_properties_only.py b/samples/client/echo_api/python/openapi_client/models/number_properties_only.py
@@ -34,7 +34,8 @@ class NumberPropertiesOnly(BaseModel):
     __properties: ClassVar[List[str]] = ["number", "float", "double"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/client/echo_api/python/openapi_client/models/pet.py b/samples/client/echo_api/python/openapi_client/models/pet.py
@@ -48,7 +48,8 @@ def status_validate_enum(cls, value):
         return value
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/client/echo_api/python/openapi_client/models/query.py b/samples/client/echo_api/python/openapi_client/models/query.py
@@ -43,7 +43,8 @@ def outcomes_validate_enum(cls, value):
         return value
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/client/echo_api/python/openapi_client/models/tag.py b/samples/client/echo_api/python/openapi_client/models/tag.py
@@ -32,7 +32,8 @@ class Tag(BaseModel):
     __properties: ClassVar[List[str]] = ["id", "name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...client/echo_api/python/openapi_client/models/test_form_object_multipart_request_marker.py b/...client/echo_api/python/openapi_client/models/test_form_object_multipart_request_marker.py
@@ -31,7 +31,8 @@ class TestFormObjectMultipartRequestMarker(BaseModel):
     __properties: ClassVar[List[str]] = ["name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/.../models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.py b/.../models/test_query_style_deep_object_explode_true_object_all_of_query_object_parameter.py
@@ -34,7 +34,8 @@ class TestQueryStyleDeepObjectExplodeTrueObjectAllOfQueryObjectParameter(BaseMod
     __properties: ClassVar[List[str]] = ["size", "color", "id", "name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...i_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.py b/...i_client/models/test_query_style_form_explode_true_array_string_query_object_parameter.py
@@ -31,7 +31,8 @@ class TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter(BaseModel):
     __properties: ClassVar[List[str]] = ["values"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/client/echo_api/python/requirements.txt b/samples/client/echo_api/python/requirements.txt
@@ -1,4 +1,4 @@
 urllib3 >= 2.1.0, < 3.0.0
 python_dateutil >= 2.8.2
-pydantic >= 2
+pydantic >= 2.11
 typing-extensions >= 4.7.1
diff --git a/samples/client/echo_api/python/setup.py b/samples/client/echo_api/python/setup.py
@@ -27,7 +27,7 @@
 REQUIRES = [
     "urllib3 >= 2.1.0, < 3.0.0",
     "python-dateutil >= 2.8.2",
-    "pydantic >= 2",
+    "pydantic >= 2.11",
     "typing-extensions >= 4.7.1",
 ]
 

diff --git a/...api3/client/petstore/python-aiohttp/petstore_api/models/additional_properties_any_type.py b/...api3/client/petstore/python-aiohttp/petstore_api/models/additional_properties_any_type.py
@@ -31,7 +31,8 @@ class AdditionalPropertiesAnyType(BaseModel):
     __properties: ClassVar[List[str]] = ["name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...penapi3/client/petstore/python-aiohttp/petstore_api/models/additional_properties_class.py b/...penapi3/client/petstore/python-aiohttp/petstore_api/models/additional_properties_class.py
@@ -31,7 +31,8 @@ class AdditionalPropertiesClass(BaseModel):
     __properties: ClassVar[List[str]] = ["map_property", "map_of_map_property"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...enapi3/client/petstore/python-aiohttp/petstore_api/models/additional_properties_object.py b/...enapi3/client/petstore/python-aiohttp/petstore_api/models/additional_properties_object.py
@@ -31,7 +31,8 @@ class AdditionalPropertiesObject(BaseModel):
     __properties: ClassVar[List[str]] = ["name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...etstore/python-aiohttp/petstore_api/models/additional_properties_with_description_only.py b/...etstore/python-aiohttp/petstore_api/models/additional_properties_with_description_only.py
@@ -31,7 +31,8 @@ class AdditionalPropertiesWithDescriptionOnly(BaseModel):
     __properties: ClassVar[List[str]] = ["name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/all_of_super_model.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/all_of_super_model.py
@@ -30,7 +30,8 @@ class AllOfSuperModel(BaseModel):
     __properties: ClassVar[List[str]] = ["_name"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...les/openapi3/client/petstore/python-aiohttp/petstore_api/models/all_of_with_single_ref.py b/...les/openapi3/client/petstore/python-aiohttp/petstore_api/models/all_of_with_single_ref.py
@@ -32,7 +32,8 @@ class AllOfWithSingleRef(BaseModel):
     __properties: ClassVar[List[str]] = ["username", "SingleRefType"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/animal.py b/samples/openapi3/client/petstore/python-aiohttp/petstore_api/models/animal.py
@@ -37,7 +37,8 @@ class Animal(BaseModel):
     __properties: ClassVar[List[str]] = ["className", "color"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...es/openapi3/client/petstore/python-aiohttp/petstore_api/models/array_of_array_of_model.py b/...es/openapi3/client/petstore/python-aiohttp/petstore_api/models/array_of_array_of_model.py
@@ -31,7 +31,8 @@ class ArrayOfArrayOfModel(BaseModel):
     __properties: ClassVar[List[str]] = ["another_property"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )

diff --git a/...napi3/client/petstore/python-aiohttp/petstore_api/models/array_of_array_of_number_only.py b/...napi3/client/petstore/python-aiohttp/petstore_api/models/array_of_array_of_number_only.py
@@ -30,7 +30,8 @@ class ArrayOfArrayOfNumberOnly(BaseModel):
     __properties: ClassVar[List[str]] = ["ArrayArrayNumber"]
 
     model_config = ConfigDict(
-        populate_by_name=True,
+        validate_by_name=True,
+        validate_by_alias=True,
         validate_assignment=True,
         protected_namespaces=(),
     )