feat: SQL Cell no longer escapes formatted string values (#2245)

This change updates bigframes/core/pyformat.py to directly embed str
values rather than escaping them first. Unit tests have been updated to
reflect this change.

---
*PR created automatically by Jules for task
[5189763854933796072](https://jules.google.com/task/5189763854933796072)*

---------

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
Co-authored-by: Shenyang Cai <sycai@users.noreply.github.com>

Author: google-labs-jules[bot]

bigframes/core/pyformat.py

@@ -104,6 +104,9 @@ def _field_to_template_value(
     if isinstance(value, bigframes.dataframe.DataFrame):
         return _table_to_sql(value._to_placeholder_table(dry_run=dry_run))
 
+    if isinstance(value, str):
+        return value
+
     return bigframes.core.sql.simple_literal(value)
 
 

tests/system/small/session/test_read_gbq_colab.py

@@ -143,7 +143,7 @@ def test_read_gbq_colab_repr_avoids_requery(maybe_ordered_session):
 def test_read_gbq_colab_includes_formatted_scalars(session):
     pyformat_args = {
         "some_integer": 123,
-        "some_string": "This could be dangerous, but we escape it",
+        "some_string": "This could be dangerous.",
         # This is not a supported type, but ignored if not referenced.
         "some_object": object(),
     }
@@ -153,7 +153,7 @@ def test_read_gbq_colab_includes_formatted_scalars(session):
     df = session._read_gbq_colab(
         """
         SELECT {some_integer} as some_integer,
-        {some_string} as some_string,
+        '{some_string}' as some_string,
         '{{escaped}}' as escaped
         """,
         pyformat_args=pyformat_args,
@@ -165,7 +165,7 @@ def test_read_gbq_colab_includes_formatted_scalars(session):
             {
                 "some_integer": pandas.Series([123], dtype=pandas.Int64Dtype()),
                 "some_string": pandas.Series(
-                    ["This could be dangerous, but we escape it"],
+                    ["This could be dangerous."],
                     dtype="string[pyarrow]",
                 ),
                 "escaped": pandas.Series(["{escaped}"], dtype="string[pyarrow]"),

tests/unit/core/test_pyformat.py

@@ -444,7 +444,7 @@ def test_pyformat_with_pandas_dataframe_not_dry_run_no_session_raises_valueerror
 
 def test_pyformat_with_query_string_replaces_variables(session):
     pyformat_args = {
-        "my_string": "some string value",
+        "my_string": "`my_table`",
         "max_value": 2.25,
         "year": 2025,
         "null_value": None,
@@ -456,19 +456,17 @@ def test_pyformat_with_query_string_replaces_variables(session):
     SELECT {year} - year  AS age,
     @myparam AS myparam,
     '{{my_string}}' AS escaped_string,
-    {my_string} AS my_string,
-    {null_value} AS null_value,
-    FROM my_dataset.my_table
+    *
+    FROM {my_string}
     WHERE height < {max_value}
     """.strip()
 
     expected_sql = """
     SELECT 2025 - year  AS age,
     @myparam AS myparam,
     '{my_string}' AS escaped_string,
-    'some string value' AS my_string,
-    NULL AS null_value,
-    FROM my_dataset.my_table
+    *
+    FROM `my_table`
     WHERE height < 2.25
     """.strip()
 

tests/unit/pandas/io/test_api.py

@@ -108,7 +108,7 @@ def test_read_gbq_colab_calls_set_location(
     mock_with_default_session.return_value = mock_df
 
     query_or_table = "SELECT {param1} AS param1"
-    sample_pyformat_args = {"param1": "value1"}
+    sample_pyformat_args = {"param1": "'value1'"}
     result = bf_io_api._read_gbq_colab(
         query_or_table, pyformat_args=sample_pyformat_args, dry_run=False
     )

tests/unit/session/test_read_gbq_colab.py

@@ -60,7 +60,7 @@ def test_read_gbq_colab_includes_formatted_values_in_dry_run(monkeypatch, dry_ru
 
     pyformat_args = {
         "some_integer": 123,
-        "some_string": "This could be dangerous, but we escape it",
+        "some_string": "some_column",
         "bf_df": bf_df,
         "pd_df": pd_df,
         # This is not a supported type, but ignored if not referenced.
@@ -84,7 +84,7 @@ def test_read_gbq_colab_includes_formatted_values_in_dry_run(monkeypatch, dry_ru
     expected = textwrap.dedent(
         f"""
         SELECT 123 as some_integer,
-        'This could be dangerous, but we escape it' as some_string,
+        some_column as some_string,
         '{{escaped}}' as escaped
         FROM `proj`.`dset`.`temp_{"table" if dry_run else "view"}` AS bf_df
         FULL OUTER JOIN `proj`.`dset`.`temp_{"table" if dry_run else "view"}` AS pd_df