title: How do I use multiple choices field (tag select field) in custom form/model?
body: <p>I'm interesting in how do I get input field working as default flask-admin multi input field:
  <a href="https://i.stack.imgur.com/KOscB.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KOscB.png" alt="enter image description here"></a>
  What widget/field should I use?</p>
  
  <p>It seems like i need to use Select2TagsField, but how do i fill it with data? It just show me 'No matches found':</p>
  
  <pre><code>class CustomModelView(ModelView):
      form_columns = ('things_list',)
      form_extra_fields = {
          'things_list': Select2TagsField(
              'Things',
              coerce=int
          ),
      }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/wkWQe.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wkWQe.png" alt="enter image description here"></a></p>