remove "comment" from the model. Copy the 'comment' field of Jamespot in the 'description' field of the model instead
<p>Books {{idBook}} :</p>
<ul ui-sortable="sortableOptions" ng:model="slides" class="list-unstyled list-inline gallery container">
<li class="col-md-3 item" ng-repeat="i in slides">
<div class="img-ctn">
<img class="img img-responsive image" ng-src="{{ i.details.images[0] }}" />
<p>{{ i.details.title }}</p>
<div class="gallery-buttons">
<a class="btn btn-default" href="#/slide/{{ i.id }}"><span class="glyphicon glyphicon-pencil"></span></a>
<a class="btn btn-default" ng-click="deleteItem($index)"><span class="glyphicon glyphicon-trash"></span></a>
</div>
</div>
</li>
</ul>