api: fix submission of empty map field data (#15504)

tests/test_api.py

@@ -682,6 +682,20 @@ def test_formdef_submit_from_wscall(pub, local_user):
     new_formdata = formdef.data_class().get(resp.json['data']['id'])
     assert str(new_formdata.user_id) == str(local_user.id)
 
+    # test missing map data
+    del formdata.data['5']
+
+    payload = json.loads(
+                json.dumps(formdata.get_json_export_dict(),
+                    cls=qommon.misc.JSONEncoder,
+                    encoding=get_publisher().site_charset))
+    signed_url = sign_url('http://example.net/api/formdefs/test/submit?orig=coucou', '1234')
+    url = signed_url[len('http://example.net'):]
+
+    resp = get_app(pub).post_json(url, payload)
+    assert resp.json['err'] == 0
+    new_formdata = formdef.data_class().get(resp.json['data']['id'])
+    assert new_formdata.data.get('5') is None
 
 def test_categories(pub):
     FormDef.wipe()

wcs/api.py

@@ -59,7 +59,7 @@ def posted_json_data_to_formdata_data(formdef, data):
     for field in formdef.get_all_fields():
         if not hasattr(field, 'from_json_value'):
             continue
-        if not field.id in data:
+        if data.get(field.id) is None:
             continue
         data[field.id] = field.from_json_value(data[field.id])