如何在Rails中提交表单时将画布图像发送到数据库

<canvas id="myCanvas" width="400" height="400"></canvas>
<form action="/submit" method="post">
  <input type="hidden" name="image_data" id="imageData">
  <input type="submit" value="Submit">
</form>

<script>
  var canvas = document.getElementById('myCanvas');
  var ctx = canvas.getContext('2d');

  // 绘制画布内容
  ctx.fillStyle = 'red';
  ctx.fillRect(0, 0, canvas.width, canvas.height);

  // 将画布内容转换为Base64编码的图像数据
  var imageData = canvas.toDataURL();
  document.getElementById('imageData').value = imageData;
</script>

class FormController < ApplicationController
  def submit
    # 获取表单提交的图像数据
    image_data = params[:image_data]

    # 解码图像数据为二进制
    binary_data = Base64.decode64(image_data['data:image/png;base64,'.length .. -1])

    # 存储到数据库中
    Image.create(data: binary_data)

    # 其他处理逻辑...

    redirect_to root_path
  end
end