title: Django form exclude options in select field
body: <p>I have one model that has a ManyToMany Field (let's call it "Options") with another Model</p>
  
  <p>When I create the ModelForm it displays all options.</p>
  
  <p>Is there any way to exclude some option values or to show only some of them?</p>
  
  <p>Here is an example:</p>
  
  <p>models.py</p>
  
  <pre><code>class Options (model.Models):
      name = ...
      ...
  
  class Anything (model.Models):
      ...
      options = ManyToManyField(Options)
  </code></pre>
  
  <p>values of "Options" in my DB:</p>
  
  <pre><code>["OK", 
  "OK_2", 
  "NOT_OK", 
  "OK_3, 
  "NOT_OK_2"]
  </code></pre>
  
  <p>Let's say that <strong>I need to show ONLY the "OK" values</strong> and hide or not to show the "NOT_OK" values.</p>
  
  <p>Is there any way to do this with ModelForms?</p>