title: Get path to ActiveStorage file on disk
body: <p>I need to get the path to the file on disk which is using <code>ActiveStorage</code>.  The file is stored locally.</p>
  
  <p>When I was using paperclip, I used the <code>path</code> method on the attachment which returned the full path.</p>
  
  <p>Example:</p>
  
  <pre><code>user.avatar.path
  </code></pre>
  
  <p>While looking at the <a href="http://edgeguides.rubyonrails.org/active_storage_overview.html#linking-to-files" rel="noreferrer"> Active Storage Docs</a>, it looked like <code>rails_blob_path</code> would do the trick.  After looking at what it returned though, it does not provide the path to the document.  Thus, it returns this error:</p>
  
  <blockquote>
    <p>No such file or directory @ rb_sysopen - </p>
  </blockquote>
  
  <p><strong>Background</strong></p>
  
  <p>I need the path to the document because I am using the <a href="https://rubygems.org/gems/combine_pdf" rel="noreferrer">combine_pdf</a> gem in order to combine multiple pdfs into a single pdf.  </p>
  
  <p>For the paperclip implementation, I iterated through the full_paths of the selected pdf attachments and <code>load</code> them into the combined pdf:</p>
  
  <pre><code>attachment_paths.each {|att_path| report &lt;&lt; CombinePDF.load(att_path)}
  </code></pre>