FEATURE: RxQuery.count()

[pubkey]

There is currently no cound-method for queries.

Goal-API:

// single-exec
const amount = await myCollection.count().where('foo').gt(10). /* .. */.exec();
console.log(amount);
// > 5

// subscription
myCollection.count().where('foo').gt(10). /* .. */.$.subscribe(nr => console.log(nr));
// > 5
await myCollection.insert({/* any docData */});
// > 6

There should be an optimisation to determine if the amount is needed once or many times (if we subscribe).
The first case should do a pouch-find-count-query, the second case should use the QueryChangeDetection for better performance.

[pubkey]

I added this feature to the backlog. Maybe this will come in the future.

[phal0r]

@pubkey
Is it still in the Backlog? I am interested in firing count queries against rxdb for one of my current projects.

[pubkey]

Yes, see here https://github.com/pubkey/rxdb/blob/master/orga/BACKLOG.md

[phal0r]

Ok, thanks. Do you have currently any plans to implement it?

[pubkey]

No. But you are also a developer ;)

[phal0r]

True. I don't hesitate to contribute to this project. Currently I am working on a project, where I actually use rxdb and I will see, if I can fit it into the project plan, but I can't promise to work on it yet and in general I thought, that you might have some plans, where you want to go with this project. This is why I asked in the first place :)

I will let you know, once there is an opportunity for this feature.

[DouglasCalora]

@phal0r how do you resolve this? I'm new at rxdb.

[phal0r]

@DouglasCalora
Currently I solve it by selecting all records from the collection and checking the length of the array. It is clear, that this is the worst approach to solve this, but I had no clue how RxDB worked back when I wrote this message.

Now I think I would be able to implement this with reasonable amount of time, but no plans to do this within the next weeks.

[pubkey]

Related: #4096