Thanks for your time mate !
In fact the problem was coming from my headers sent by the front-end it was not generating the right content-type as the server-side was only accepting json and the content-type sent were application/json json.
This was a pain to debug because the inspection made on the parameters sent was not called as the request were not even reaching the controllers logic.
But this is also due to the fact that I only have a 3 weeks background on elixir/phoenix…
So if anyone has the same problem check your requests headers and be sure that you allow them through CORSplug options !
