(superset) 01/01: fix(key): make cached key optional for chart preview

[as...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

alexandrusoare pushed a commit to branch alexandrusoare/fix/preview_chart_optional_key
in repository https://gitbox.apache.org/repos/asf/superset.git

commit 151f1a81815be5121430b89ce4fcf974a7789138
Author: alexandrusoare <al...@gmail.com>
AuthorDate: Mon Apr 27 14:29:00 2026 +0300

    fix(key): make cached key optional for chart preview
---
 superset/mcp_service/chart/schemas.py                  |  8 +++++++-
 .../mcp_service/chart/tool/update_chart_preview.py     |  7 +++----
 .../chart/tool/test_update_chart_preview.py            | 18 ++++++++++++++++++
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/superset/mcp_service/chart/schemas.py b/superset/mcp_service/chart/schemas.py
index 2323c10232a..ab142096b92 100644
--- a/superset/mcp_service/chart/schemas.py
+++ b/superset/mcp_service/chart/schemas.py
@@ -1574,7 +1574,13 @@ class UpdateChartRequest(QueryCacheControl):
 
 
 class UpdateChartPreviewRequest(FormDataCacheControl):
-    form_data_key: str = Field(..., description="Existing form_data_key to update")
+    form_data_key: str | None = Field(
+        None,
+        description=(
+            "Existing form_data_key to update"
+            " (omit for fresh preview from config + dataset_id)"
+        ),
+    )
     dataset_id: int | str = Field(..., description="Dataset ID or UUID")
     config: Dict[str, Any] = Field(..., description=_CHART_CONFIG_DESCRIPTION)
     generate_preview: bool = True
diff --git a/superset/mcp_service/chart/tool/update_chart_preview.py b/superset/mcp_service/chart/tool/update_chart_preview.py
index 1c2eba5580b..38b7a5abfdc 100644
--- a/superset/mcp_service/chart/tool/update_chart_preview.py
+++ b/superset/mcp_service/chart/tool/update_chart_preview.py
@@ -90,14 +90,13 @@ def update_chart_preview(
     """Update cached chart preview without saving.
 
     IMPORTANT:
-    - Modifies cached form_data from generate_chart (save_chart=False)
-    - Original form_data_key is invalidated, new one returned
+    - Original form_data_key (when provided) is invalidated, new one returned
     - LLM clients MUST display explore_url to users
 
     Use when:
-    - Modifying preview before deciding to save
+    - Creating a fresh preview from config + dataset_id (omit form_data_key)
+    - Modifying an existing preview before deciding to save
     - Iterating on chart design without creating permanent charts
-    - Testing different configurations
 
     Returns new form_data_key, preview images, and explore URL.
     """
diff --git a/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py b/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py
index c80f2797a47..691fe3eb169 100644
--- a/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py
+++ b/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py
@@ -374,6 +374,24 @@ class TestUpdateChartPreview:
             )
             assert request.form_data_key == key
 
+    @pytest.mark.asyncio
+    async def test_update_chart_preview_form_data_key_optional(self):
+        """Test that form_data_key can be omitted for fresh previews."""
+        config = TableChartConfig(
+            chart_type="table",
+            columns=[ColumnRef(name="col1")],
+        )
+
+        # Omit form_data_key entirely
+        request = UpdateChartPreviewRequest(dataset_id=1, config=config)
+        assert request.form_data_key is None
+
+        # Explicitly pass None
+        request2 = UpdateChartPreviewRequest(
+            form_data_key=None, dataset_id=1, config=config
+        )
+        assert request2.form_data_key is None
+
     @pytest.mark.asyncio
     async def test_update_chart_preview_cache_control(self):
         """Test cache control parameters in update preview request."""