RestAPI: CustomJSONEncoder support bytes objects

In Aiida 2.0, REST (where flask 1 was updated to flask 2), bytes objects are not supported anymore.
Because Flask 1.x was based on simplejson, that inherently converts bytes objects into strings.
In flask 2.0.0, it was redesigned based on the default python json.
See here: https://flask.palletsprojects.com/en/2.0.x/changes/ and here pallets/flask#3555
The conversion of a bytes array into `str` in the `CustomJSONEncoder` is implemented to workaround.

Co-authored-by: Jusong Yu <jusong.yeu@gmail.com>

Cherry-pick: ef9c544

aiida/restapi/common/utils.py

@@ -56,6 +56,12 @@ def default(self, o):
                                    o.hour).zfill(2), str(o.minute).zfill(2),
                                          str(o.second).zfill(2)])
 
+        # To support bytes objects, try to decode to a string
+        try:
+            return o.decode('utf-8')
+        except (UnicodeDecodeError, AttributeError):
+            pass
+
         # If not returned yet, do it in the default way
         return JSONEncoder.default(self, o)
 

tests/restapi/test_routes.py

@@ -1014,6 +1014,21 @@ def test_structure_download(self):
         structure_data = load_node(node_uuid)._exportcontent('xsf')[0]  # pylint: disable=protected-access
         assert rv_obj.data == structure_data
 
+    def test_structure_download_false(self):
+        """
+        Test download=false that displays the content in the browser instead
+        of downloading the structure file
+        """
+        from aiida.orm import load_node
+
+        node_uuid = self.get_dummy_data()['structuredata'][0]['uuid']
+        url = f'{self.get_url_prefix()}/nodes/{node_uuid}/download?download_format=xsf&download=False'
+        with self.app.test_client() as client:
+            rv_obj = client.get(url)
+            response = json.loads(rv_obj.data)
+        structure_data = load_node(node_uuid)._exportcontent('xsf')[0]  # pylint: disable=protected-access
+        assert response['data']['download']['data'] == structure_data.decode('utf-8')
+
     def test_cif(self):
         """
         Test download of cif file