public async Task<bool> AssociatePicturesWithPoll<TQuestion>(PollBase<TQuestion> pollBase,PicturesAssociateMode mode) where TQuestion:Question
{
var pollId = pollBase.Id;
var resultsTasks = pollBase.Questions.Select(async question =>
{
var questionResultsTasks = question.AnswerOptions!=null?
question.AnswerOptions.Select(async option =>
option.PictureId != null ? await UpdatePictureMetadataAsync(option.PictureId, pollId, mode) : null).ToList()
:new List<Task<UpdateResult>>();
var questionResults = (await Task.WhenAll(questionResultsTasks)).ToList();
questionResults.Add(question?.PictureId != null ? await UpdatePictureMetadataAsync(question.PictureId, pollId, mode) : null);
return questionResults;
});
var results=(await Task.WhenAll(resultsTasks)).SelectMany(list=>list).ToList();
return results.Where(result=>result!=null).All(result => result.ModifiedCount == 1);
}
private async Task<BsonArray> GetNewPictureMetadataAsync(string id,string pollId, PicturesAssociateMode mode)
{
ObjectId.TryParse(id, out ObjectId oid);
var filter = Builders<GridFSFileInfo>.Filter.Eq("_id", oid);
var fileInfo = await Bucket.Find(filter).SingleAsync();
var bsonArray = fileInfo.Metadata["related_polls"].AsBsonArray;
switch (mode)
{
case PicturesAssociateMode.Link:
bsonArray.Add(pollId);
break;
case PicturesAssociateMode.Unlink:
bsonArray.Remove(pollId);
break;
}
return bsonArray;
}
private async Task<UpdateResult> UpdatePictureMetadataAsync(string pictureId, string pollId, PicturesAssociateMode mode)
{
if (! await ExistsAsync(pictureId))
return null;
var filesCollection = _db.GetCollection<BsonDocument>("fs.files");
ObjectId.TryParse(pictureId, out ObjectId oid);
var filter = Builders<BsonDocument>.Filter.Eq("_id", oid);
var bsonArray = await GetNewPictureMetadataAsync(pictureId, pollId,mode);
if (bsonArray.Count == 0)
{
await DeleteAsync(pictureId);
return null;
}
var update = Builders<BsonDocument>.Update.Set("metadata.related_polls", bsonArray);
return await filesCollection.UpdateOneAsync(filter, update);
}
