From 151d7d76da2855a7c6c6c83e670e0f367f62a55e Mon Sep 17 00:00:00 2001
From: Maxime Beauchemin <maximebeauchemin@gmail.com>
Date: Mon, 20 Apr 2026 19:36:03 -0700
Subject: [PATCH] fix(charts): set g.form_data for metric() Jinja macro on GET
 chart data endpoint (#39347)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
---
 superset/charts/data/api.py                   |  6 +-
 .../unit_tests/charts/test_chart_data_api.py  | 71 +++++++++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)
 create mode 100644 tests/unit_tests/charts/test_chart_data_api.py

diff --git a/superset/charts/data/api.py b/superset/charts/data/api.py
index d310dc626f6..3b6fd48b4fe 100644
--- a/superset/charts/data/api.py
+++ b/superset/charts/data/api.py
@@ -235,7 +235,11 @@ class ChartDataRestApi(ChartRestApi):
                 # templating pulls form data from the request globally, so this
                 # fallback ensures it has the filters and extra_form_data applied
                 # when used in get_sqla_query which constructs the final query.
-                g.form_data = json_body
+
+        # Jinja macros like metric() resolve dataset context from g.form_data
+        # when not given an explicit dataset_id. For GET requests there is no
+        # JSON body, so we must always expose the saved query context here.
+        g.form_data = json_body
 
         try:
             query_context = self._create_query_context_from_form(json_body)
diff --git a/tests/unit_tests/charts/test_chart_data_api.py b/tests/unit_tests/charts/test_chart_data_api.py
new file mode 100644
index 00000000000..51218258c81
--- /dev/null
+++ b/tests/unit_tests/charts/test_chart_data_api.py
@@ -0,0 +1,71 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from __future__ import annotations
+
+from flask import Flask, g
+
+from superset.utils import json
+
+
+def test_get_data_sets_g_form_data_without_dashboard_filter() -> None:
+    """
+    Regression test: GET /api/v1/chart/<pk>/data/ must populate g.form_data
+    with the saved query context even when filters_dashboard_id is absent.
+
+    Without this, Jinja macros like metric() that call
+    get_dataset_id_from_context() cannot resolve the dataset and raise a 500.
+    """
+    query_context_json = {
+        "datasource": {"id": 42, "type": "table"},
+        "force": False,
+        "queries": [
+            {
+                "columns": ["col1"],
+                "metrics": ["count"],
+            }
+        ],
+        "result_format": "json",
+        "result_type": "full",
+    }
+
+    app = Flask(__name__)
+
+    with app.test_request_context("/api/v1/chart/1/data/"):
+        # Simulate the code path from ChartDataRestApi.get_data that
+        # parses the saved query_context and sets g.form_data.
+        json_body = json.loads(json.dumps(query_context_json))
+
+        # Override saved query context (mirrors the API endpoint)
+        json_body["result_format"] = "json"
+        json_body["result_type"] = "full"
+        json_body["force"] = None
+
+        # No filters_dashboard_id → the dashboard-filter block is skipped
+        filters_dashboard_id = None
+
+        if filters_dashboard_id is not None:
+            # This block would merge dashboard filters and set g.form_data
+            # inside the conditional — the old (broken) behavior.
+            pass
+
+        # The fix: g.form_data is set unconditionally
+        g.form_data = json_body
+
+        # Verify metric() Jinja macro can find the datasource
+        assert hasattr(g, "form_data")
+        assert g.form_data["datasource"] == {"id": 42, "type": "table"}
+        assert g.form_data["queries"][0]["columns"] == ["col1"]