MemberDownloadData:对象数组
ImageInfo:实体模型
var Imageinfo = MemberDownloadData.Select(p => new ObjectId(p.ImageId));
FilterDefinitionBuilder<ImageInfo> builderFilter = Builders<ImageInfo>.Filter;
FilterDefinition<ImageInfo> filter = builderFilter.In("_id", Imageinfo.ToArray());
var img_data = await _repositoryImg.Find(filter, Builders<ImageInfo>.Projection
.Include(p => p._id)
.Include(p => p.ThumbnailPathList)
.Include(p => p.Title));
