grain property only supports direct column references

[plaflamme]

We have a table that uses BigQuery's RANGE type like so:

MODEL(
  name foo,
  grain (id, RANGE_START(valid_date_range))
);
SELECT id::STRING, RANGE(valid_from, valid_to)::RANGE<DATE> AS valid_date_range

This works fine except when loading the ui which results in this kind of error:

Reference 'RANGE_START(valid_date_range)' must have an inferrable name or explicit alias.

Traceback (most recent call last):
  File ".venv/lib/python3.11/site-packages/web/server/settings.py", line 102, in get_loaded_context
    yield _get_loaded_context(settings.project_path, settings.config, settings.gateway)
sqlmesh.utils.errors.ConfigError: Reference 'RANGE_START(valid_date_range)' must have an inferrable name or explicit alias.

We do not see errors anywhere else when using RANGE_START(...) in the grain definition, only in the UI.

[izeigerman]

@tobymao this looks like remnants of the metrics layer?

[tobymao]

grain is also used in table diff

[georgesittas]

Would it work to specify an alias in this case? E.g., this model doesn't have the issue @plaflamme mentioned:

MODEL(
  name foo,
  grain (id, RANGE_START(valid_date_range) AS valid_date_range_start)
);

WITH t AS (
  SELECT
    '1' AS id,
    DATE('2025-05-06') AS valid_from,
    DATE('2020-05-07') AS valid_to
)
SELECT
  id::STRING AS id,
  RANGE(valid_from, valid_to)::RANGE<DATE> AS valid_date_range
FROM t

I think expecting a valid output name and not an arbitrary expression may be intentional in this case, because as Toby said grains are, e.g., used in table diff where you want to reference it by name. Otherwise how would you specify the expression grain shown here?