title: Django Admin import_export module used for custom IMPORT
body: <p>I was trying to follow official doc of <code>import-export</code>:</p>
  
  <p><a href="https://django-import-export.readthedocs.org/en/latest/import_workflow.html#import-data-method-workflow" rel="nofollow">https://django-import-export.readthedocs.org/en/latest/import_workflow.html#import-data-method-workflow</a></p>
  
  <p>But I still do not know how to glue it to my admin <strong>assuming that</strong>:</p>
  
  <ol>
  <li><p>I want only subset of fields (I created Resource model with listed fields, but It crashes while importing anyway with: <code>KeyError</code> full stack bellow.</p></li>
  <li><p>Where - <strong>in which method</strong> - in my admin class (inheriting of course <code>ImportExportModelAdmin</code> and using defined <code>resource_class</code>) should i place the code responsible for some custom actions I want to happen <strong>after</strong> validating, that import data are correct but <strong>before</strong> inserting them into database.</p></li>
  </ol>
  
  <p>I am not very advanced in Django and will be thankful for some hints.
  Example of working implementation will be appreciated, so if you know something similar on github - share.</p>