kgabryje opened a new pull request, #38955:
URL: https://github.com/apache/superset/pull/38955
### SUMMARY
The MCP `generate_chart` tool only supported ad-hoc metrics (column name +
aggregate function). When an LLM used `get_dataset_info` and saw saved metrics
like "total_revenue" (expression: `SUM(amount) / COUNT(*)`), it could not
reference them in chart generation — it had to reconstruct them as ad-hoc
expressions, which breaks for complex SQL expressions.
This PR adds a `saved_metric: bool` flag to `ColumnRef`. When `true`, the
`name` field references a saved metric from the dataset, and the form_data
output uses a plain string (which Superset's query engine already resolves via
`metrics_by_name` lookup).
**Changes:**
- `schemas.py`: Added `saved_metric` field to `ColumnRef` with a model
validator that clears `aggregate` when set. Updated label computation in
`TableChartConfig` and `XYChartConfig` validators.
- `chart_utils.py`: `create_metric_object` returns a plain string for saved
metrics. `map_table_config` routes saved metrics to the metrics list.
`_humanize_column` handles saved metric labels.
- `dataset_validator.py`: Skips aggregation validation for saved metrics
(they have built-in aggregation).
Fully backward-compatible — `saved_metric` defaults to `False`.
### BEFORE/AFTER SCREENSHOTS OR ANIMATED GIF
N/A — backend-only change to MCP tool schemas.
### TESTING INSTRUCTIONS
1. Use `get_dataset_info` to find a dataset with saved metrics
2. Use `generate_chart` with a saved metric reference:
```json
{
"dataset_id": 1,
"config": {
"chart_type": "xy",
"x": {"name": "order_date"},
"y": [{"name": "total_revenue", "saved_metric": true}]
}
}
```
3. Verify the chart renders correctly using the saved metric
4. Run tests: `pytest
tests/unit_tests/mcp_service/chart/test_chart_schemas.py
tests/unit_tests/mcp_service/chart/test_chart_utils.py -x`
### ADDITIONAL INFORMATION
- [ ] Has associated issue:
- [ ] Required feature flags:
- [ ] Changes UI
- [ ] Includes DB Migration (follow approval process in
[SIP-59](https://github.com/apache/superset/issues/13351))
- [ ] Migration is atomic, supports rollback & is backwards-compatible
- [ ] Confirm DB migration upgrade and downgrade tested
- [ ] Runtime estimates and downtime expectations provided
- [x] Introduces new feature or API
- [ ] Removes existing feature or API
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