finishing adding linked resources to edit pages on tool path

web/app/templates/edit.html

         <label for="linked_practice_id">Linked resources</label>
     </div>
     <div class="mb-3 mt-3">
-      {{ links }}
         <select name="linked_resources" id="linked_resources" aria-label="Linked resources" class="selectpicker" data-live-search="true" multiple>
           {% for resource_dropdown in resource_dropdown %}
             {% if resource_dropdown['type'] != 'tool' %}
-              <option value="{{ resource_dropdown['id'] }}">{{ resource_dropdown['name'] }}</option>
+              {% if resource_dropdown in links %}
+                <option value="{{ resource_dropdown['id'] }}" selected>{{ resource_dropdown['name'] }}</option>
+              {% else %}
+                <option value="{{ resource_dropdown['id'] }}">{{ resource_dropdown['name'] }}</option>
+              {% endif %}
             {% endif %}
           {% endfor %}
         </select>

web/app/tool.py

             db.session.commit()
             if linked_resource:
                 for linked_resource in request.form.getlist('linked_resources'):
-                    first_resource_id = tool_id
-                    second_resource_id = linked_resource
-                    new_relationship = Relationship(first_resource_id=first_resource_id, second_resource_id=second_resource_id)
+                    link = Resource.query.get(linked_resource)
+                    if link not in links:
+                        first_resource_id = tool_id
+                        second_resource_id = linked_resource
+                        new_relationship = Relationship(first_resource_id=first_resource_id, second_resource_id=second_resource_id)
 
-                    # add the new relationship to the database
-                    db.session.add(new_relationship)
-                    db.session.commit()
+                        # add the new relationship to the database
+                        db.session.add(new_relationship)
+                        db.session.commit()
             return redirect(url_for('tool.get_tools'))
 
     return render_template('edit.html', resource=tool, resource_dropdown=resource_dropdown, links=links)