Perform Interim Operations in Transaction

Data Service
1

This question is in reference to this topic:

Is support for this still planned? If so, is there an anticipated release date?

Thanks!

2

Hi John,

There were some improvements, though they were not as encompassing due to security and query injection concerns. Could you please describe your scenario, perhaps there would be a solution already?

Regards,
Mark

3

Hey Mark,

Here is my use-case.

Given the following Data tables:

  1. Topic (has options that can be “voted” on - 1:n relation to TopicOption)
  2. TopicOption (An option for a Topic that can be voted on)
  3. VoteRecord (record of a user’s vote for a Topic & TopicOption)
  4. UserSettings (has a “voteRecord” column that is a 1:n relationship to VoteRecord entries)

The scenario I have in mind is to handle voting on Topics with a server transaction. User’s can vote on a Topic by selecting an option. User’s can change a vote for a Topic but not “remove” it.

Request Body

{
	"optionId": <option_id>,
	"topicId": <topic_object_id>,
	"userId": <user_object_id>,
}

Check for existing VoteRecord entries where userId = ‘userId’ and topicId = ‘topicId’

If an entry exists:
Update VoteRecord optionId with the new value
Update (decrement) the previously voted option’s “votes” count
Update (increment) the new option’s “votes” count

else:
Create a new VoteRecord
Add new VoteRecord object to user’s “voteRecord” relation.
Update (increment) TopicOption “votes” count
Update (increment) Topic “totalVotes” count

Let me know if this needs clarification/simplification. Thanks again.

4

Where does ‘count’ field reside?

5

If the ‘vote’ is a record in ‘VoteRecord’ which in its turn related to the user: you can just add or remove record to that table. And the count request to that table will give you desired number of votes.

6

@oleg-vyalyh both ‘Topic’ and ‘TopicOption’ objects have a column labeled ‘votes’ - that is the count I am referring to.

Correct, a vote is an object in the VoteRecord table. The reason I want to update the ‘count’ columns as mentioned above, is to have the number of votes for a Topic (and it’s individual options) available without additional requests. Hence why I am trying to update those values within a transaction.

7

Now I understand.
One more question. One user can vote more than once for specific pair of Topic & TopicOption ?

8

A user can change their vote for a Topic. So if a Topic has 3 options and the user votes for optionA, then later wants to change that vote, they can. The way I mapped it out in my head was to update the Vote record that existed for that user/Topic/TopicOption, rather than remove it and create another.

Voting for a Topic/TopicOption the user has already voted for, is handled client side.

9

I’m talking not about the changing the target (either topic or option) of the vote.

My question was:
Сan the user vote more than once for specific pair of Topic & TopicOption ?
If no – I would advise to try approach which I described above.
Your VoteRecord is already uniquely point to the combination of user,topic,topicoption. So, you just have to remove one record and create another one.
In such a case you receive the ability to get flexible statistics with different combinations of user,topic,topicoption.

10

Сan the user vote more than once for specific pair of Topic & TopicOption ?

No, they cannot.

Your VoteRecord is already uniquely point to the combination of user,topic,topicoption. So, you just have to remove one record and create another one.
In such a case you receive the ability to get flexible statistics with different combinations of user,topic,topicoption.

Correct, we’re already doing that. The Topic and TopicOption tables both have a “votes” column. These “counter” values keep track of the number of votes. For a TopicOption, this is the number of VoteRecords with the particular TopicOption objectId. For a Topic, it’s all VoteRecords with that particular Topic objectId. This way a Topic’s vote count is retrievable within the Topic object. Same for a TopicOption.

These “votes” columns are they values I want to update within the transaction - when the user casts their vote. If the client is displaying a list of Topics, I need to be able to show the number of votes as well, without additional requests.

11

Basically I am trying to use the votes column in Topic/TopicOption as an atomic counter. I had hoped to be able to update those values using transactions. Could this be done by passing the current values into the request body (using the scenario from above)? I feel that could also allow clients to be using incorrect data, though.

12

Hi @John_Admin !

Unfortunatelly currently there is no other way to do it completelly on server side in transaction. Sorry for inconvenience.
We already have internal ticket BKNDLSS-20855 for feature which would feet your need but it will take several releases to add it to server and SDKs.

Regards, Andriy

13

@Andriy_Konoz I see, thanks for the update!

I will have keep an eye on future releases for this, as well as BKNDLSS-24678, which is preventing RT connections on Flutter. These are the only things preventing a migration from existing services.