getone for external sql backend

[sirex]

Current external SQL backend does not support getone action.

When I try send following request:

http GET "$SERVER/$DATASET/City/47cb18cb-77e7-4216-852d-122c9214a3af"

I get following error:

HTTP/1.1 500 Internal Server Error

{
    "errors": [
        {
            "code": "NotImplementedError",
            "message": "Could not find signature for getone: <Context, Model, Sql>"
        }
    ]
}

Server logs show:

Traceback (most recent call last):
  File "multipledispatch/dispatcher.py", line 269, in __call__
    func = self._cache[types]
           ~~~~~~~~~~~^^^^^^^
KeyError: (
    <class 'spinta.components.Context'>,
    <class 'spinta.components.Model'>,
    <class 'spinta.datasets.backends.sql.components.Sql'>,
)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "gspinta/api.py", line 95, in homepage
    return await create_http_response(context, params, request)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "gspinta/utils/response.py", line 129, in create_http_response
    return await commands.getone(
           ^^^^^^^^^^^^^^^^^^^^^^
  File "gspinta/commands/read.py", line 301, in getone
    resp = await commands.getone(
           ^^^^^^^^^^^^^^^^^^^^^^
  File "gspinta/commands/read.py", line 354, in getone
    data = commands.getone(context, model, backend, id_=params.pk)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "multipledispatch/dispatcher.py", line 273, in __call__
    raise NotImplementedError(
NotImplementedError: Could not find signature for getone: <Context, Model, Sql>

To fix this, we need get local id from keymap.db and then run SQL query with local id, to get the data.