title: drupal: how to post a comment through services API?
body: <p>I am currently developping a mobile application with a drupal 7 website as a backend. Using the services API with a REST server I was able to easily access the nodes, users, files and comments to see their content. 
  I am able via a POST request to log in the website but I cannot create a comment through the services API. Actually, there is no error and a new comment is well created in the database but it is empty and its nid is 0. 
  I also tried to download a valid comment, modify it with new datas, and send it but I have the same result.
  I also need to add that the comments I am using or not just simple ones, they include some specific fields in their form.
  Can anyone help me to solve this problem ? Has anyone ever experience something similar ?
  Thank you</p>