从模型获取画布高度和宽度，并使用这些尺寸创建画布

Question

So in my mind this should be pretty simply but I cannot seem to get this right. When creating a whiteboard, the user inputs two numbers, height and width. I'm trying to apply these given numbers to the canvas object but am struggling. Here's my code:

Answer 1

<div id=thecanvas>
    <canvas id="board" width="<%= @whiteboard.canvas_width %>" 
                       height="<%= @whiteboard.canvas_height %>">
    </canvas>
</div>

Rails expects <%= %> tags for Ruby code in a template file.