Unable to use objects with only `additionalProperties` (no pre-defined fields) within schema

[pirate]

I have a pydantic model that has a field like so:

class MySchemaModel(BaseModel):
    my_mapping: Dict[str, str] = Field(default={})

DEFAULT = MySchemaModel()

class Model(models.Model):
    test_field: MySchemaModel = SchemaField(default=DEFAULT)

This field contains a mapping of str to str and I Want users to be able to add their own entries , but the default contains no pre-defined keys/properties, so it throws an error right now:

Error: Error while creating EditorState: Invalid schema: Schema of type 'object' must have at least one of these keys: ['properties' or 'keys' or 'oneOf' or 'anyOf' or 'allOf']

I think the issue can be fixed by adding an empty properties: {} entry to the schema generation /conversion code before it gets passed to django-jsonform:
MySchemaModel().model_json_schema()

{
    "properties": {
        "my_mapping": {
            "additionalProperties": {
                "type": "string"
            },
            "default": {},
            "title": "My Mapping",
+           "properties": {},
            "type": "object"
        }
    },
    "title": "MySchemaModel",
    "type": "object"
}

I think django-jsonform should also natively support objects with no properties/keys defined if they have additionalProperties set. I commented on a related an issue on their side here: bhch/django-jsonform#144.

[pirate]

As a workaround I've monkey-patched JSONFormWidget to achieve the desired behavior:

from django.contrib import admin

from django_jsonform.widgets import JSONFormWidget
from django_pydantic_field.v2.fields import PydanticSchemaField

from project.models import Dependency


def patch_schema_for_jsonform(schema):
    """recursively patch a schema dictionary in-place to fix any missing properties/keys on objects"""

    # base case: schema is type: "object" with no properties/keys
    if schema.get('type') == 'object' and not ('properties' in schema or 'keys' in schema):
        if 'default' in schema and isinstance(schema['default'], dict):
            schema['properties'] = {
                key: {"type": "string", "default": value}
                for key, value in schema['default'].items()
            }
            # setting the actual value as a default on a hardcoded property is still not ideal as it doesn't allow the user to remove this entry from the UI, but at least it shows up
        else:
            schema['properties'] = {}

    # recursive case: iterate through all values and process any sub-objects
    for key, value in schema.items():
        if isinstance(value, dict):
            patch_schema_for_jsonform(value)



class PatchedJSONFormWidget(JSONFormWidget):
    def get_schema(self):
        self.schema = super().get_schema()
        patch_schema_for_jsonform(self.schema)
        return self.schema



class DependencyAdmin(admin.ModelAdmin):
    formfield_overrides = {PydanticSchemaField: {"widget": PatchedJSONFormWidget}}

admin.site.register(Dependency, DependencyAdmin)

Taken from my pydantic-pkgr code for editing this BinProvider model in the UI: https://github.com/ArchiveBox/pydantic-pkgr/blob/main/pydantic_pkgr/binprovider.py#L171