Default value of enum field isn't an enum member

[Twixes]

Describe the bug

This is similar to #1797, but specifically about enums. When running datamodel-codegen on the schema below, the result includes

class PropertyOperator(str, Enum):
    exact = "exact"
    is_not = "is_not"
    icontains = "icontains"
    not_icontains = "not_icontains"

class EventPropertyFilter(BaseModel):
    operator: Optional[PropertyOperator] = "exact"

This is invalid, because "exact" is not an instance of PropertyOperator.

To Reproduce

Example schema:

{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "definitions": {
        "EventPropertyFilter": {
            "properties": {
                "operator": {
                    "$ref": "#/definitions/PropertyOperator",
                    "default": "exact"
                }
            },
            "required": ["operator"],
            "type": "object"
        },
        "PropertyOperator": {
            "enum": [
                "exact",
                "is_not",
                "icontains",
                "not_icontains"
            ],
            "type": "string"
        }
    }
}

Used commandline:

$ datamodel-codegen \
    --class-name='SchemaRoot' --collapse-root-models --target-python-version 3.10 --disable-timestamp \
    --use-one-literal-as-default --use-default --use-default-kwarg --use-subclass-enum \
    --input-file-type jsonschema --output-model-type pydantic_v2.BaseModel

Expected behavior

The output should be this:

 class EventPropertyFilter(BaseModel):
-    operator: Optional[PropertyOperator] = "exact"
+    operator: Optional[PropertyOperator] = PropertyOperator("exact")

Version:

• OS: macOS 14.4.1
• Python version: 3.10
• datamodel-code-generator version: 0.25.5

[koxudaxi]

@Twixes
We have the --set-default-enum-member to set the enum member as the default value.

 --set-default-enum-member
                        Set enum members as default values for enum field

...

class EventPropertyFilter(BaseModel):
    operator: Optional[PropertyOperator] = PropertyOperator.exact

[Twixes]

Thank you! I missed --set-default-enum-member completely, but it's perfect.