how can I exclude a pydantic field from the schema?

Question

some of the fields in a pydantic class are actually internal representation and not something I want to serialize or put in a schema. I am trying various methods to exclude them but nothing seems to work.

here's one approach where I use the exclue=True and exclude_schema=True of a Field

class MyItem(BaseModel):
    name: str = Field(...)
    data: str = Field(...)

class MyObject(BaseModel):
    items_dict: dict[str, MyItem] = Field(..., exclude=True, exclude_schema=True)
    
    @property
    def items_list(self):
      return list(self.items_dict.values())

    @root_validator(pre=True)
    @classmethod
    def encode_decode_items(cls, values):
        items = values.get('items_dict')
        if isinstance(items, dict):
            values['items_dict'] = list(items.values())
        elif isinstance(items, list):
            values['items_dict'] = validate_items(items)
        return values

obj = MyObject(items_dict=[MyItem(name='item1', data='data1'), MyItem(name='item2', data='data2')])

print(json.dumps(obj.model_json_schema(), indent=2))

however in the schema the field is still there:

{
  "$defs": {
    "MyItem": {
      "properties": {
        "name": {
          "title": "Name",
          "type": "string"
        },
        "data": {
          "title": "Data",
          "type": "string"
        }
      },
      "required": [
        "name",
        "data"
      ],
      "title": "MyItem",
      "type": "object"
    }
  },
  "properties": {
    "items_dict": {
      "additionalProperties": {
        "$ref": "#/$defs/MyItem"
      },
      "exclude_schema": true,
      "title": "Items Dict",
      "type": "object"
    }
  },
  "required": [
    "items_dict"
  ],
  "title": "MyObject",
  "type": "object"
}