Nullable integer definitions cannot validate

[kirpit]

Even the simplest form of nullable integer definitions cannot validate legit inputs. See example below.

SCHEMA = {
    "type": "object",
    "properties": {
        "age": {
            "type": ["integer", "null"],
            "title": "Age Integer",
            "description": "An integer field that is nullable"
        },
    },
    "required": []
}

class BugDemoModel(models.Model):
    name = models.CharField(max_length=100)
    data = JSONField(schema=SCHEMA, blank=True, null=True)

    def __str__(self):
        return self.name

Expected behaviour:
Any valid integer value for the age field to be validated and accepted in admin form.

Error message:

Invalid value. Only numbers allowed.

NB: it works and validates fine with "type": "integer".

[kirpit]

Meanwhile, this is how I am working around the issue that I can admit looks quite ugly but it's the only quick solution I could come up with.

"""
This module is a work around the issue of django-jsonform not handling
nullable integers correctly. It provides a custom JSONFormField that
overrides the to_python method to cast nullable integers properly.

See: https://github.com/bhch/django-jsonform/issues/192
"""

from django_jsonform.forms.fields import JSONFormField
from django_jsonform.models.fields import JSONField


class DocumentJSONFormField(JSONFormField):
    def __init__(self, *args, schema=None, **kwargs):
        super().__init__(*args, schema=schema, **kwargs)
        self.schema = schema
        
    def to_python(self, value):
        value = super().to_python(value)
        value = self._cast_nullable_integers(value, self.schema, self.schema)
        return value

    def _cast_nullable_integers(self, data, schema, root_schema):
        if isinstance(schema, dict):
            # Handle $ref
            if "$ref" in schema:
                ref_path = schema["$ref"]
                # Only supports local refs like "#/$defs/question"
                if ref_path.startswith("#/"):
                    parts = ref_path.lstrip("#/").split("/")
                    ref = root_schema
                    for part in parts:
                        ref = ref.get(part)
                    if ref is not None:
                        return self._cast_nullable_integers(data, ref, root_schema)
            if schema.get("type") == ["integer", "null"]:
                if data is None:
                    return None
                if isinstance(data, str) and data.isdigit():
                    return int(data)
            if schema.get("type") == "object" and "properties" in schema:
                return {
                    k: self._cast_nullable_integers(data.get(k), v, root_schema)
                    for k, v in schema["properties"].items()
                    if k in data
                }
            if schema.get("type") == "array" and "items" in schema:
                return [
                    self._cast_nullable_integers(item, schema["items"], root_schema)
                    for item in (data or [])
                ]
        return data


class DocumentJSONField(JSONField):
    def formfield(self, **kwargs):
        defaults = {"form_class": DocumentJSONFormField}
        defaults.update(kwargs)
        return super().formfield(**defaults)

and use this DocumentJSONField instead of JSONField coming from django-jsonform library. Hope this helps others until there is a permanent fix.