Fix RootModel default value not being applied

Author: koxudaxi

docs/cli-reference/model-customization.md

@@ -5029,7 +5029,7 @@ where optional fields have defaults but cannot accept `None` values.
 
 
     class Id(BaseModel):
-        __root__: int
+        __root__: int = 1
 
 
     class Description(BaseModel):

docs/cli-reference/template-customization.md

@@ -2625,7 +2625,7 @@ helps maintain consistency with codebases that prefer double-quote formatting.
 
 
     class Zoom(BaseModel):
-        __root__: confloat(ge=0.0, le=25.0)
+        __root__: confloat(ge=0.0, le=25.0) = 0
     ```
 
 ---

src/datamodel_code_generator/model/template/pydantic/BaseModel_root.jinja2

@@ -24,7 +24,7 @@ class {{ class_name }}({{ base_class }}):{% if comment is defined %}  # {{ comme
     {%- else %}
     __root__: {{ field.type_hint }}
     {%- endif %}
-    {%- if not field.has_default_factory_in_field and not (field.required or (field.represented_default == 'None' and field.strip_default_none))
+    {%- if not field.has_default_factory_in_field and not ((field.required and not field.has_default) or (field.represented_default == 'None' and field.strip_default_none))
             %} = {{ field.represented_default }}
     {%- endif -%}
     {%- endif %}

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

@@ -42,7 +42,7 @@ class {{ class_name }}({{ base_class }}{%- if fields -%}[{{get_type_hint(fields,
     {%- else %}
     root: {{ field.type_hint }}
     {%- endif %}
-    {%- if not field.has_default_factory_in_field and not (field.required or (field.represented_default == 'None' and field.strip_default_none))
+    {%- if not field.has_default_factory_in_field and not ((field.required and not field.has_default) or (field.represented_default == 'None' and field.strip_default_none))
             %} = {{ field.represented_default }}
     {%- endif -%}
     {%- endif %}

tests/data/expected/main/jsonschema/all_of_any_of_base_class_ref.py

@@ -75,4 +75,4 @@ class Pitch(BaseModel):
 
 
 class Zoom(BaseModel):
-    __root__: confloat(ge=0.0, le=25.0)
+    __root__: confloat(ge=0.0, le=25.0) = 0

tests/data/expected/main/jsonschema/has_default_value.py

@@ -17,19 +17,19 @@ class TeamType(Enum):
 
 
 class ID(BaseModel):
-    __root__: str
+    __root__: str = 'abc'
 
 
 class Pet(BaseModel):
     name: str | None = None
 
 
 class Family(BaseModel):
-    __root__: list[ID]
+    __root__: list[ID] = ['abc', 'efg']
 
 
 class FamilyPets(BaseModel):
-    __root__: list[Pet]
+    __root__: list[Pet] = ['taro', 'shiro']
 
 
 class Person(BaseModel):

tests/data/expected/main/openapi/nullable.py

@@ -57,7 +57,7 @@ class Email(BaseModel):
 
 
 class Id(BaseModel):
-    __root__: int
+    __root__: int = 1
 
 
 class Description(BaseModel):

tests/data/expected/main/openapi/nullable_strict_nullable.py

@@ -57,7 +57,7 @@ class Email(BaseModel):
 
 
 class Id(BaseModel):
-    __root__: int
+    __root__: int = 1
 
 
 class Description(BaseModel):

tests/data/expected/main/openapi/nullable_strict_nullable_use_union_operator.py

@@ -57,7 +57,7 @@ class Email(BaseModel):
 
 
 class Id(BaseModel):
-    __root__: int
+    __root__: int = 1
 
 
 class Description(BaseModel):

tests/data/expected/main/openapi/referenced_default.py

@@ -8,7 +8,7 @@
 
 
 class ModelSettingB(RootModel[confloat(ge=0.0, le=10.0)]):
-    root: confloat(ge=0.0, le=10.0)
+    root: confloat(ge=0.0, le=10.0) = 5
 
 
 class Model(BaseModel):