Implement ClassVar feature in code without changing template

Author: ubaumann

src/datamodel_code_generator/model/pydantic/base_model.py

@@ -19,7 +19,7 @@
     DataModelFieldBase,
 )
 from datamodel_code_generator.model._types import WrappedDefault
-from datamodel_code_generator.model.base import UNDEFINED
+from datamodel_code_generator.model.base import UNDEFINED, repr_set_sorted
 from datamodel_code_generator.model.pydantic.imports import (
     IMPORT_ANYURL,
     IMPORT_EXTRA,
@@ -250,18 +250,34 @@ def __str__(self) -> str:  # noqa: PLR0912
         elif self.required:
             field_arguments = ["...", *field_arguments]
         elif not default_factory:
-            from datamodel_code_generator.model.base import repr_set_sorted  # noqa: PLC0415
-
             default_repr = repr_set_sorted(self.default) if isinstance(self.default, set) else repr(self.default)
             field_arguments = [default_repr, *field_arguments]
 
+        if self.is_class_var:
+            return repr_set_sorted(self.default) if isinstance(self.default, set) else repr(self.default)
+
         return f"Field({', '.join(field_arguments)})"
 
+    @property
+    def is_class_var(self) -> bool:
+        return self.extras.get("x-is-classvar") is True
+
+    @property
+    def type_hint(self) -> str:
+        """Get the type hint including ClassVar if applicable."""
+        # if self.name == "name":
+        #     breakpoint()
+        if self.is_class_var:
+            return f"ClassVar[{super().type_hint}]"
+        return super().type_hint
+
     @property
     def annotated(self) -> str | None:
         """Get the Annotated type hint if use_annotated is enabled."""
         if not self.use_annotated or not str(self):
             return None
+        if self.is_class_var:
+            return self.type_hint
         return f"Annotated[{self.type_hint}, {self!s}]"
 
     @property

src/datamodel_code_generator/model/pydantic_v2/base_model.py

@@ -188,14 +188,6 @@ def _has_discriminator_in_data_type(self) -> bool:
         """Check if any nested DataType has a discriminator."""
         return any(dt.discriminator for dt in self.data_type.all_data_types)
 
-    @property
-    def class_var_type_hint(self) -> str:
-        return f"ClassVar[{self.type_hint}]"
-
-    @property
-    def is_class_var(self) -> bool:
-        return self.extras.get("x-is_classvar") is True
-
     @property
     def imports(self) -> tuple[Import, ...]:
         """Get all required imports including AliasChoices and Field for discriminator."""

src/datamodel_code_generator/model/template/pydantic_v2/BaseModel.jinja2

@@ -16,9 +16,7 @@ class {{ class_name }}({{ base_class }}):{% if comment is defined %}  # {{ comme
 {%- endfilter %}
 {%- endif %}
 {%- for field in fields %}
-    {%- if field.is_class_var and field.represented_default %}
-    {{ field.name }}: {{ field.class_var_type_hint }} = {{ field.represented_default }}
-    {%- elif not field.annotated and field.field %}
+    {%- if not field.annotated and field.field %}
     {{ field.name }}: {{ field.type_hint }} = {{ field.field }}
     {%- else %}
     {%- if field.annotated %}

tests/data/jsonschema/has_classvar_extra.json

@@ -3,7 +3,7 @@
     "properties": {
         "namespace": {
             "type": "string",
-            "x-is_classvar": true,
+            "x-is-classvar": true,
             "default": "test"
         }
     }