async void PostCommentClick(object sender, EventArgs args)
        {
            if (Constantes.authModel != null && Constantes.authModel.Connected)
            {
                bool succeed = await CommentsModel.PostComment(comment.Text, placeID);

                if (succeed)
                {
                    DependencyService.Get <IMessage>().ShortAlert("Thanks for your comment !");

                    Place p = CommentsModel.GetPlaceWithComments(placeID);
                    BindingContext = new PlaceDetailsViewModel {
                        BindedPlace = p
                    };
                    ListComments.ItemsSource = p.comments;
                }
                else
                {
                    DependencyService.Get <IMessage>().ShortAlert("An error occured while posting your comment. Please try again later.");
                }
            }
            else
            {
                DependencyService.Get <IMessage>().ShortAlert("You must be logged to comment.");
            }
            comment.Text = "";
        }