BUG: to_json not allowing uploads to S3 (pandas-dev#28375)

Author: YagoGG

pandas/core/generic.py

@@ -98,6 +98,7 @@
 from pandas.core.missing import find_valid_index
 from pandas.core.ops import _align_method_FRAME
 
+from pandas.io.common import get_filepath_or_buffer
 from pandas.io.formats import format as fmt
 from pandas.io.formats.format import DataFrameFormatter, format_percentiles
 from pandas.io.formats.printing import pprint_thing
@@ -2259,6 +2260,11 @@ def to_json(
         config.is_nonnegative_int(indent)
         indent = indent or 0
 
+        if path_or_buf is not None:
+            path_or_buf, _, _, _ = get_filepath_or_buffer(
+                path_or_buf, compression=compression, mode="w"
+            )
+
         return json.to_json(
             path_or_buf=path_or_buf,
             obj=self,

pandas/tests/io/json/test_pandas.py

@@ -5,6 +5,8 @@
 import json
 import os
 
+import boto3
+from moto import mock_s3
 import numpy as np
 import pytest
 
@@ -1662,3 +1664,13 @@ def test_json_multiindex(self, dataframe, expected):
         series = dataframe.stack()
         result = series.to_json(orient="index")
         assert result == expected
+
+    @mock_s3
+    def test_to_s3(self):
+        # GH 28375
+        mock_bucket_name, target_file = "mybucket", "test.json"
+        conn = boto3.resource("s3")
+        bucket = conn.create_bucket(Bucket=mock_bucket_name)
+        df = DataFrame({"x": [1, 2, 3], "y": [2, 4, 6]})
+        df.to_json(f"s3://{mock_bucket_name}/{target_file}")
+        assert target_file in (obj.key for obj in bucket.objects.all())