Performs validations on conn.params If all validations are successful returns the connection struct Otherwise returns an error map in the following structure: %{param: ["some error", ...]} Will call the given on_error callback in case some validation failed

Init the Request.Validator.Plug with an optional error callback and handlers with their corresponding request validator module.

plug Request.Validator.Plug,
  register: App.Requests.RegisterRequest,
  on_error: fn conn, errors -> json_resp(conn, "Handle your errors: #{inspect errors}") endcopy

The default callback to be invoked when there is a param that fails validation.