BUG: Fix bug when using df.query with "str.contains()"

doc/source/whatsnew/v0.25.0.rst

@@ -412,6 +412,7 @@ Other
 
 - Improved :class:`Timestamp` type checking in various datetime functions to prevent exceptions when using a subclassed `datetime` (:issue:`25851`)
 - Bug in :class:`Series` and :class:`DataFrame` repr where ``np.datetime64('NaT')`` and ``np.timedelta64('NaT')`` with ``dtype=object`` would be represented as ``NaN`` (:issue:`25445`)
+- Bug in :class:`BaseExprVisitor` which caused :func:`eval` expressions to fail when named keyword arguments were included within the expression string (:issue:`25813`)
 -
 -
 

pandas/core/computation/expr.py

@@ -632,11 +632,8 @@ def visit_Call(self, node, side=None, **kwargs):
                 if not isinstance(key, ast.keyword):
                     raise ValueError("keyword error in function call "
                                      "'{func}'".format(func=node.func.id))
-
                 if key.arg:
-                    # TODO: bug?
-                    kwargs.append(ast.keyword(
-                        keyword.arg, self.visit(keyword.value)))  # noqa
+                    kwargs[key.arg] = self.visit(key.value)()
 
             return self.const_type(res(*new_args, **kwargs), self.env)
 

pandas/tests/computation/test_eval.py

@@ -1757,6 +1757,29 @@ def test_no_new_globals(self, engine, parser):
         assert gbls == gbls2
 
 
+class TestEvalNamedKWargs(object):
+    # xref https://github.com/pandas-dev/pandas/issues/25813
+
+    def test_eval_with_kwargs(self, engine, parser):
+        def fn(x):
+            return 2 * x
+        result = pd.eval("fn(x=2)", engine=engine, parser=parser)
+        assert result == 4
+
+    def test_query_str_contains(self, parser):
+        df = pd.DataFrame([["I", "XYZ"], ["IJ", None]], columns=['A', 'B'])
+
+        expected = df[df["A"].str.contains("J")]
+        result = df.query("A.str.contains('J')", engine="python",
+                          parser=parser)
+        tm.assert_frame_equal(result, expected)
+
+        expected = df[df["B"].str.contains("Z", na=False)]
+        result = df.query("B.str.contains('Z', na=False)", engine="python",
+                          parser=parser)
+        tm.assert_frame_equal(result, expected)
+
+
 @td.skip_if_no_ne
 def test_invalid_engine():
     msg = 'Invalid engine \'asdf\' passed'