feat: refined file.key support

To work around that scan does not return a `url` field.

LC ticket: 38823
slack: https://xindong.slack.com/archives/C01TLAHFTBJ/p1639134311164500

Author: weakish

leancloud/file_.py

@@ -289,6 +289,8 @@ def _update_data(self, server_data):
         if "url" in server_data:
             self._url = server_data.get("url")
             self._successful_url = self._url
+        if "key" in server_data:
+            self.key = server_data.get("key")
         if "mime_type" in server_data:
             self._mime_type = server_data["mime_type"]
         if "metaData" in server_data:

leancloud/utils.py

@@ -137,8 +137,9 @@ def decode(key, value):
     if _type == "File":
         f = leancloud.File(value["name"])
         meta_data = value.get("metaData")
+        key = value.get("key")
         if meta_data:
-            f._metadata = meta_data
+            f._metadata = meta_data  
         f._url = value["url"]
         f._successful_url = value["url"]
         f.id = value["objectId"]

tests/test_file.py

@@ -149,6 +149,10 @@ def test_query():  # type: () -> None
         assert f.url
         assert f.name
         assert f.metadata
+        if f.metadata.get("__source") == 'external':
+            assert f.url
+        else:
+            assert f.key
 
     assert isinstance(leancloud.File.query.first(), File)
 
@@ -157,9 +161,13 @@ def test_scan():  # type: () -> None
     files = leancloud.Query("File").scan()
     for f in files:
         assert isinstance(f, File)
-        assert f.key
         assert f.name
         assert f.metadata
+        if f.metadata.get("__source") == 'external':
+            assert f.url
+        else:
+            assert f.key
+        
 
 @with_setup(setup_func)
 def test_save_external():  # type: () -> None