public async void Fetch()
{
Filtered = false;
Pattern = string.Empty;
CommentStatus = "获取中，请稍等";
CanFetch = false;
var comments = await CommentModel.FetchMoment(MomentId, total => CommentStatus = $"获取中，已获取{total}条评论");
_comments.Clear();
foreach (var comment in comments)
{
_comments.Add(comment);
}
CanFetch = true;
CommentStatus = $"已获取{_comments.Count}条评论";
OnPropertyChanged(nameof(Comments));
OnPropertyChanged(nameof(FilterResult));
OnPropertyChanged(nameof(Ready));
}