adding deletion function to practices

web/app/practice.py

         name = request.form['name']
         description = request.form['description']
         linked_resources = request.form.getlist('linked_resources')
+        remove_linked_resources = request.form.getlist('remove_linked_resources')
 
         if not name:
             flash('Name is required!')
                         add_linked_resource(practice_id, linked_resource)
                     elif not links:
                         add_linked_resource(practice_id, linked_resource)
+            if remove_linked_resources:
+                for remove_linked_resource in remove_linked_resources:
+                    delete_relationship(practice_id, remove_linked_resource)
             return redirect(url_for('practice.get_practices'))
 
     return render_template('edit.html', resource=practice, resource_dropdown=resource_dropdown, links=links)

web/app/resources.py

     flash('Successfully deleted!')
 
 # function to delete a single relationship
-def delete_relationship(first_resource_id, second_resource_id):
-    relation = Relationship.query.filter((Relationship.first_resource_id == first_resource_id) & (Relationship.second_resource_id == second_resource_id)).first()
+def delete_relationship(main_id, for_deletion_id):
+    relation = Relationship.query.filter(((Relationship.first_resource_id == main_id) & (Relationship.second_resource_id == for_deletion_id)) | ((Relationship.first_resource_id == for_deletion_id) & (Relationship.second_resource_id == main_id))).first()
     deletion = Relationship.query.get(relation.id)
     db.session.delete(deletion)
     db.session.commit()

web/app/templates/edit.html

           {% for resource_dropdown in resource_dropdown %}
             {% if resource_dropdown['type'] != 'tool' %}
               {% if links and resource_dropdown in links %}
-                <option value="{{ resource_dropdown['id'] }}" selected>{{ resource_dropdown['name'] }}</option>
+                <option value="" selected>{{ resource_dropdown['name'] }}</option>
               {% else %}
                 <option value="{{ resource_dropdown['id'] }}">{{ resource_dropdown['name'] }}</option>
               {% endif %}