From caf06a45e3f36cc3d3507be607d8ce99d706080b Mon Sep 17 00:00:00 2001
From: Shuowei Li <shuowei@google.com>
Date: Fri, 6 Mar 2026 23:11:12 +0000
Subject: [PATCH] fix(describe): add count aggregation for JSON and OBJ_REF
 types

---
 bigframes/pandas/core/methods/describe.py  |  5 +++++
 tests/system/small/pandas/test_describe.py | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/bigframes/pandas/core/methods/describe.py b/bigframes/pandas/core/methods/describe.py
index 6fd7960daf3..f4082a5a25d 100644
--- a/bigframes/pandas/core/methods/describe.py
+++ b/bigframes/pandas/core/methods/describe.py
@@ -120,5 +120,10 @@ def _get_aggs_for_dtype(dtype) -> list[aggregations.UnaryAggregateOp]:
         dtypes.TIME_DTYPE,
     ]:
         return [aggregations.count_op, aggregations.nunique_op]
+    elif dtype in [
+        dtypes.JSON_DTYPE,
+        dtypes.OBJ_REF_DTYPE,
+    ]:
+        return [aggregations.count_op]
     else:
         return []
diff --git a/tests/system/small/pandas/test_describe.py b/tests/system/small/pandas/test_describe.py
index 6f288115128..96b8adfd373 100644
--- a/tests/system/small/pandas/test_describe.py
+++ b/tests/system/small/pandas/test_describe.py
@@ -352,3 +352,22 @@ def test_series_groupby_describe(scalars_dfs):
             check_dtype=False,
             check_index_type=False,
         )
+
+
+def test_describe_json_and_obj_ref_returns_count(session):
+    # Test describe() works on JSON and OBJ_REF types (without nunique, which fails)
+    sql = """
+        SELECT
+            PARSE_JSON('{"a": 1}') AS json_col,
+            'gs://cloud-samples-data/vision/ocr/sign.jpg' AS uri_col
+    """
+    df = session.read_gbq(sql)
+
+    df["obj_ref_col"] = df["uri_col"].str.to_blob()
+    df = df.drop(columns=["uri_col"])
+
+    res = df.describe(include="all").to_pandas()
+
+    assert "count" in res.index
+    assert res.loc["count", "json_col"] == 1.0
+    assert res.loc["count", "obj_ref_col"] == 1.0