title: Django how to open file in FileField
body: <p>I need to open a file saved in a FileField, create a list with the content of the file and pass it to the template. How can I open the file? I tried <code>with open(stocklist.csv_file.url, "wb")</code> but it gave me a "File not found" error. If I do this:</p>
  
  <pre><code>csv_file = stocklist.csv_file.open(mode="rb")
  </code></pre>
  
  <p><code>csv_file</code> is <code>None</code>. However, there is a file. If I print <code>print("stocklist.csv_file.url: %s" % stocklist.csv_file.url)</code> I do get </p>
  
  <p>stocklist.csv_file:  <a href="https://d391vo1.cloudfront.net/csv_pricechart/...ss7.csv" rel="nofollow noreferrer">https://d391vo1.cloudfront.net/csv_pricechart/...ss7.csv</a></p>
  
  <p>And if I go to the admin, I can download the file. So, how can I open a file saved in a <code>FileField</code>?</p>