Unicode Characters Causing XML Data Error

[alroyer]

In our application, we have products with metadata entered by our customers. Some of them need to input Unicode characters, often using the degree symbol (°).

However, when this symbol appears in the metadata value, we encounter the following error:

ValueError: All strings must be XML compatible: Unicode or ASCII, no NULL bytes or control characters.

Here is a snippet of code to reproduce this error:

from spyne import Application, ServiceBase, Unicode, rpc
from spyne.model.complex import Array, ComplexModel, XmlAttribute, XmlData
from spyne.protocol.http import HttpRpc
from spyne.protocol.soap import Soap11
from spyne.server.wsgi import WsgiApplication


class Metadata(ComplexModel):
    _type_info = [
        ("name", XmlAttribute(Unicode(sub_name="name"))),
        ("value", XmlData(Unicode(sub_name="value"))),
    ]


class Product(ComplexModel):
    _type_info = [
        ("metadata", Array(Metadata)),
    ]


class ProductService(ServiceBase):
    @rpc(_returns=Product)
    def get_product(ctx):
        product = Product()
        product.metadata = [
            Metadata(name="name", value="°"),
        ]
        return product


wsgi_app = WsgiApplication(
    Application(
        [ProductService],
        tns="spyne.examples",
        in_protocol=HttpRpc(validator="soft"),
        out_protocol=Soap11(),
    )
)

Python 3.10.15

Package    Version
---------- -------
gunicorn   23.0.0
lxml       5.3.0
packaging  24.1
pip        24.2
pytz       2024.2
setuptools 74.1.2
spyne      2.14.0

[alroyer]

We found a workaround:

from spyne import Application, ServiceBase, Unicode, rpc
from spyne.model.complex import Array, ComplexModel, XmlAttribute, XmlData
from spyne.protocol.http import HttpRpc
from spyne.protocol.soap import Soap11
from spyne.server.wsgi import WsgiApplication


class MetadataValue(XmlData):
    @classmethod
    def marshall(cls, prot, name, value, parent_elt):
        if isinstance(value, str):
            parent_elt.text = value
        else:
            super().marshall(prot, name, value, parent_elt)


class Metadata(ComplexModel):
    _type_info = [
        ("name", XmlAttribute(Unicode(sub_name="name"))),
        ("value", MetadataValue(Unicode(sub_name="value"))),
    ]


class Product(ComplexModel):
    _type_info = [
        ("metadata", Array(Metadata)),
    ]


class ProductService(ServiceBase):
    @rpc(_returns=Product)
    def get_product(ctx):
        product = Product()
        product.metadata = [
            Metadata(name="name", value="value"),
            Metadata(name="name", value="<>{}&'\"°"),
        ]
        return product


wsgi_app = WsgiApplication(
    Application(
        [ProductService],
        tns="spyne.examples",
        in_protocol=HttpRpc(validator="soft"),
        out_protocol=Soap11(),
    )
)