Unexpected behavior from 'connection' resolver.

[woh-dev]

It's been amazing working with graphql-compose-mongoose over the last few weeks and discovering how powerful it is. Thank you for this incredible tool!

I am starting to use the 'connection' resolver that is built in to grapqhl-compose-mongoose, (not the plugin available at graphql-compose-connection). It works as expected when I use the forward pagination arguments first and after.

But when I try to paginate in reverse using last and before I get some unexpected behavior.

Here's an example:

(last: 2, before: "")

r-0
r-1
r-2
r-3
r-4
r-5 
r-6 
r-7 
r-8 
r-9 <- result
r-10 <- result

I then try to get the next two pages.

(last: 2, before: "r-9")

r-0 <- actual result
r-1 <- actual result
r-2
r-3
r-4
r-5 
r-6 
r-7 <- expected result
r-8 <- expected result
r-9 
r-10 

Am I misunderstanding how this should work?

I saw this issue on the graphql-compose-connection docs.

graphql-compose/graphql-compose-connection#7

Is it possible that the fixes from this issue were not implemented in graphql-compose-mongoose?

[nodkz]

Hm, it's very strange.
Just added test case for graphql-compose-connection It works as you describe with expected results.

I think the problem somewhere in this package (graphql-compose-mongoose). I'll try to look at on it tomorrow. Too tired today.

Will be nice if you add broken test case here https://github.com/graphql-compose/graphql-compose-mongoose/tree/master/src/__tests__/guthub_issues with name 120-test.js
It help me a lot to save time. Tnx.

[nodkz]

@woh-dev I resolved a problem. Please check and give me feedback - work it or not.

Please install graphql-compose-connection@3.2.1 in your app. It has a problem with the fallback algorithm when sort argument not provided for backward connection.

Anyway, I recommend you to use sort argument when using connections. It helps to avoid overfetching/underfetching problem. Without sorting under the hood used limit/skip logic which not guarantee that you do not get the same records for next request.

[nodkz]

Also was created a test file with your case and it works like you expect with graphql-compose-connection@3.2.1
https://github.com/graphql-compose/graphql-compose-mongoose/blob/master/src/__tests__/guthub_issues/120-test.js

[woh-dev]

Thanks, I went on vacation just after posting this, so I will take a look at this now!

[woh-dev]

@nodkz, to confirm -- the connection feature is now working correctly after I upgraded to "graphql-compose-mongoose": "^5.0.0",

Thank you thank you! Glad this bug was resolved so quickly!