fix: allow __repr__ to work with uninitialized DataFrame/Series/Index

bigframes/core/indexes/base.py

@@ -243,6 +243,11 @@ def query_job(self) -> Optional[bigquery.QueryJob]:
         return self._query_job
 
     def __repr__(self) -> str:
+        # Protect against errors with uninitialized Series. See:
+        # https://github.com/googleapis/python-bigquery-dataframes/issues/728
+        if not hasattr(self, "_block"):
+            return object.__repr__(self)
+
         # TODO(swast): Add a timeout here? If the query is taking a long time,
         # maybe we just print the job metadata that we have so far?
         # TODO(swast): Avoid downloading the whole series by using job

bigframes/dataframe.py

@@ -574,9 +574,18 @@ def _getitem_bool_series(self, key: bigframes.series.Series) -> DataFrame:
         return DataFrame(block)
 
     def __getattr__(self, key: str):
+        # Protect against recursion errors with uninitialized DataFrame
+        # objects. See:
+        # https://github.com/googleapis/python-bigquery-dataframes/issues/728
+        # and
+        # https://nedbatchelder.com/blog/201010/surprising_getattr_recursion.html
+        if key == "_block":
+            raise AttributeError("_block")
+
         if key in self._block.column_labels:
             return self.__getitem__(key)
-        elif hasattr(pandas.DataFrame, key):
+
+        if hasattr(pandas.DataFrame, key):
             raise AttributeError(
                 textwrap.dedent(
                     f"""
@@ -585,8 +594,7 @@ def __getattr__(self, key: str):
                     """
                 )
             )
-        else:
-            raise AttributeError(key)
+        raise AttributeError(key)
 
     def __setattr__(self, key: str, value):
         if key in ["_block", "_query_job"]:
@@ -616,6 +624,11 @@ def __repr__(self) -> str:
 
         Only represents the first `bigframes.options.display.max_rows`.
         """
+        # Protect against errors with uninitialized DataFrame. See:
+        # https://github.com/googleapis/python-bigquery-dataframes/issues/728
+        if not hasattr(self, "_block"):
+            return object.__repr__(self)
+
         opts = bigframes.options.display
         max_results = opts.max_rows
         if opts.repr_mode == "deferred":

bigframes/series.py

@@ -281,6 +281,11 @@ def reset_index(
             return bigframes.dataframe.DataFrame(block)
 
     def __repr__(self) -> str:
+        # Protect against errors with uninitialized Series. See:
+        # https://github.com/googleapis/python-bigquery-dataframes/issues/728
+        if not hasattr(self, "_block"):
+            return object.__repr__(self)
+
         # TODO(swast): Add a timeout here? If the query is taking a long time,
         # maybe we just print the job metadata that we have so far?
         # TODO(swast): Avoid downloading the whole series by using job

tests/unit/core/test_indexes.py

@@ -0,0 +1,39 @@
+# Copyright 2024 Google LLC
+#
+# Licensed 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.
+
+import bigframes.core.indexes
+
+
+def test_index_repr_with_uninitialized_object():
+    """Ensures Index.__init__ can be paused in a visual debugger without crashing.
+
+    Regression test for https://github.com/googleapis/python-bigquery-dataframes/issues/728
+    """
+    # Avoid calling __init__ to simulate pausing __init__ in a debugger.
+    # https://stackoverflow.com/a/6384982/101923
+    index = object.__new__(bigframes.core.indexes.Index)
+    got = repr(index)
+    assert "Index" in got
+
+
+def test_multiindex_repr_with_uninitialized_object():
+    """Ensures MultiIndex.__init__ can be paused in a visual debugger without crashing.
+
+    Regression test for https://github.com/googleapis/python-bigquery-dataframes/issues/728
+    """
+    # Avoid calling __init__ to simulate pausing __init__ in a debugger.
+    # https://stackoverflow.com/a/6384982/101923
+    index = object.__new__(bigframes.core.indexes.MultiIndex)
+    got = repr(index)
+    assert "MultiIndex" in got

tests/unit/test_dataframe.py

@@ -15,9 +15,23 @@
 import google.cloud.bigquery
 import pytest
 
+import bigframes.dataframe
+
 from . import resources
 
 
+def test_dataframe_repr_with_uninitialized_object():
+    """Ensures DataFrame.__init__ can be paused in a visual debugger without crashing.
+
+    Regression test for https://github.com/googleapis/python-bigquery-dataframes/issues/728
+    """
+    # Avoid calling __init__ to simulate pausing __init__ in a debugger.
+    # https://stackoverflow.com/a/6384982/101923
+    dataframe = bigframes.dataframe.DataFrame.__new__(bigframes.dataframe.DataFrame)
+    got = repr(dataframe)
+    assert "DataFrame" in got
+
+
 def test_dataframe_to_gbq_invalid_destination(monkeypatch: pytest.MonkeyPatch):
     dataframe = resources.create_dataframe(monkeypatch)
 

tests/unit/test_series.py

@@ -0,0 +1,27 @@
+# Copyright 2024 Google LLC
+#
+# Licensed 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.
+
+import bigframes.series
+
+
+def test_series_repr_with_uninitialized_object():
+    """Ensures Series.__init__ can be paused in a visual debugger without crashing.
+
+    Regression test for https://github.com/googleapis/python-bigquery-dataframes/issues/728
+    """
+    # Avoid calling __init__ to simulate pausing __init__ in a debugger.
+    # https://stackoverflow.com/a/6384982/101923
+    series = bigframes.series.Series.__new__(bigframes.series.Series)
+    got = repr(series)
+    assert "Series" in got