Default value from schema does not appear in produced data class

[Thomasb81]

Hello

test.xsd:

<xs:schema xmlns:ns="http://www.test.org" xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="http://www.test.org/" elementFormDefault="qualified">
	<xs:element name="root">
		<xs:complexType>
			<xs:sequence>
                            <xs:element name="property1" type="xs:boolean" default="false"/>
                            <xs:element name="property2" type="xs:boolean" minOccurs="0" default="false"/>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
</xs:schema>

xsdata generate test.xsd

I got:

from dataclasses import dataclass, field
from typing import Optional

__NAMESPACE__ = "http://www.test.org/"


@dataclass
class Root:
    class Meta:
        name = "root"
        namespace = "http://www.test.org/"

    property1: bool = field(
        default=True,
        metadata={
            "type": "Element",
            "required": True,
        },
    )
    property2: Optional[bool] = field(
        default=None,
        metadata={
            "type": "Element",
        },
    )

The default value for property1 is present in the generated code but value for property2 has been replace by None. This is done https://github.com/tefra/xsdata/blob/113322b57c2b6f53db2c911fed6ebd1ae40923b8/xsdata/codegen/handlers/sanitize_attributes_default_value.py#L51-L53

I understand that we have incompatible concept, on one hand we have schema that can specify both an optional element and a default value and on an other hand we have https://peps.python.org/pep-0557/ which define field and default value, which is probably why currently the tool remove data previously read from schema.

For my application I would like to be able to retrieve the default value specified in the schema. The business logic will handle it, so I don't want to rely on defaulting mechanism from dataclasses. On the provided example, I would like to produce from a custom plugin where I can customize the rending following code :

@dataclass
class Root:
    class Meta:
        name = "root"
        namespace = "http://www.test.org/"

    property1: bool = field(
        metadata={
            "type": "Element",
            "required": True,
            "default": True,
        }
    )
    property2: bool = field(
        metadata={
            "type": "Element",
            "default": False,
        }
    )

The field default attribute is not anymore produce and the default value is produced in metadata dict. Would you accept patch on sanitize_attributes_default_value.py to avoid losing default attribute value ?

Also I don't understand:

 attr.fixed = False