Fix TypeError on using pathlib.Path as key on FEEDS settings (#5384)

scrapy/settings/__init__.py

@@ -375,9 +375,13 @@ class BaseSettings(MutableMapping):
         return len(self.attributes)
 
     def _to_dict(self):
-        return {k: (v._to_dict() if isinstance(v, BaseSettings) else v)
+        return {self._get_key(k): (v._to_dict() if isinstance(v, BaseSettings) else v)
                 for k, v in self.items()}
 
+    def _get_key(self, key_value):
+        return (key_value if isinstance(key_value, (bool, float, int, str, type(None)))
+                else str(key_value))
+
     def copy_to_dict(self):
         """
         Make a copy of current settings and convert to a dict.

tests/test_cmdline/__init__.py

@@ -64,3 +64,7 @@ class CmdlineTest(unittest.TestCase):
         settingsdict = json.loads(settingsstr)
         self.assertCountEqual(settingsdict.keys(), EXTENSIONS.keys())
         self.assertEqual(200, settingsdict[EXT_PATH])
+
+    def test_pathlib_path_as_feeds_key(self):
+        self.assertEqual(self._execute('settings', '--get', 'FEEDS'),
+                         json.dumps({"items.csv": {"format": "csv", "fields": ["price", "name"]}}))

tests/test_cmdline/settings.py

@@ -1,5 +1,14 @@
+from pathlib import Path
+
 EXTENSIONS = {
     'tests.test_cmdline.extensions.TestExtension': 0,
 }
 
 TEST1 = 'default'
+
+FEEDS = {
+    Path('items.csv'): {
+        'format': 'csv',
+        'fields': ['price', 'name'],
+    },
+}