swiftからrailsサーバーにpostすると、rejectされる(error:500)

前提・実現したいこと

railsをサーバ、swiftをクライアントにした簡単なチャットアプリを開発しています。
JSONapiを利用した通信で、チャットのメッセージの内容がrailsサーバにポストできない(rejectされる)問題が発生しています。

発生している問題・エラーメッセージ

responseJSONをresponseStringにした時の結果↓

swift
1[Result]: SUCCESS: <!DOCTYPE html>
2<html>
3<head>
4  <title>We're sorry, but something went wrong (500)</title>
5  <meta name="viewport" content="width=device-width,initial-scale=1">
6  <style>
7  //略
8  </style>
9</head>
10
11<body class="rails-default-error-page">
12  <!-- This file lives in public/500.html -->
13  <div class="dialog">
14    <div>
15      <h1>We're sorry, but something went wrong.</h1>
16    </div>
17    <p>If you are the application owner check the logs for more information.</p>
18  </div>
19</body>
20</html>
21

該当のソースコード

swift
1override func didPressSend(_ button: UIButton!, withMessageText text: String!, senderId: String!, senderDisplayName: String!, date: Date!) {
2        
3        //キーボードを閉じる
4        self.view.endEditing(true)
5        
6        //メッセージを追加
7        let message = JSQMessage(senderId: senderId, displayName: senderDisplayName, text: text)
8        self.messages.append(message!)
9        
10        let parameters: Parameters = [
11            "text": message!.text
12        ]
13        
14        Alamofire.request("https://floating-wildwood-37299.herokuapp.com/api/messages",
15                          method: .post,
16                          parameters: parameters,
17                          encoding: JSONEncoding.default).responseString { response in
18                            debugPrint(response)
19        }
20
21        //送信を反映
22        self.finishReceivingMessage(animated: true)
23        
24        //textFieldをクリアする
25        self.inputToolbar.contentView.textView.text = ""
26    }

rake routes の結果、該当部分

rails
1api_messages GET    /api/messages(.:format)      api/messages#index
2                        POST   /api/messages(.:format)      api/messages#create

APIのコントローラー

class Api::MessagesController < ApplicationController
  def index
    //・・・略
  end
  
  def create
    @userid = User.count
    @messageid = Message.count + 1
    Message.create!(id: "#{@messageid}", content: "#{create_params}", user_id: "#{@userid}")
  end
  
  private
    def create_params
      params.require.permit(:text)
    end

end

herokuのlog

heroku[web.1]: State changed from starting to up																							
app[web.1]: I, [2018-05-07T03:54:46.083453 #10]  INFO -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3] Started POST "/api/messages" for 111.102.179.225 at 2018-05-07 03:54:46	+0000																						
app[web.1]: I, [2018-05-07T03:54:46.175587 #10]  INFO -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3] Processing by Api::MessagesController#create as */*																							
app[web.1]: I, [2018-05-07T03:54:46.175751 #10]  INFO -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3]   Parameters: {"text"=>"Gkdddddddd", "message"=>{}}																							
app[web.1]: D, [2018-05-07T03:54:46.203983 #10] DEBUG -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3]    (1.8ms)  SELECT COUNT(*) FROM "users"																							
app[web.1]: D, [2018-05-07T03:54:46.212653 #10] DEBUG -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3]    (1.6ms)  SELECT COUNT(*) FROM "messages"																							
app[web.1]: I, [2018-05-07T03:54:46.215776 #10]  INFO -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3] Completed 500 Internal Server Error in 40ms (ActiveRecord: 27.3ms)																							
app[web.1]: F, [2018-05-07T03:54:46.218188 #10] FATAL -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3]																							
app[web.1]: F, [2018-05-07T03:54:46.221196 #10] FATAL -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3] ArgumentError (wrong number of arguments (given 0, expected 1)):																							
app[web.1]: F, [2018-05-07T03:54:46.221323 #10] FATAL -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3]																							
app[web.1]: F, [2018-05-07T03:54:46.221439 #10] FATAL -- : [e6b4a80a-3c75-437a-81af-dcdb5b6180d3] app/controllers/api/messages_controller.rb:23:in `create_params'																							
app[web.1]: [e6b4a80a-3c75-437a-81af-dcdb5b6180d3] app/controllers/api/messages_controller.rb:18:in `create'																							
heroku[router]: at=info method=POST path="/api/messages" host=floating-wildwood-37299.herokuapp.com request_id=e6b4a80a-3c75-437a-81af-dcdb5b6180d3 fwd="111.102.179.225"	dyno=web.1	connect=0ms	service=152ms	status=500	bytes=1891	protocol=https