title: cakephp : how to displays the checkbox value that has been selected in from edit
body: <pre><code>echo $this-&gt;Form-&gt;input('product_id', array(
                                                  'label'=&gt;false,
                                                  'type'=&gt;'select',
                                                  'multiple'=&gt;'checkbox',
                                                  'options'=&gt;$product,
  
  
                                              )); 
  </code></pre>
  
  <p>I am trying to adding 'checked=>true' in from input but failed</p>
  
  <p><a href="https://i.stack.imgur.com/wMTpl.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wMTpl.png" alt="this is screenshoot of the form edit, the data already selected is not checked"></a></p>
  
  <p>this is screenshoot of the form edit, the data already selected is not checked</p>