graphql/dataloader

[QUESTION] How should I paginate my data using DataLoader?

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#231 opened on Dec 5, 2019

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 (20 comments) (8 reactions) (0 assignees)JavaScript (12,520 stars) (556 forks)batch import
help wanted

Description

I have the following query:

{
  user(id: $id) {
    username
    comments(last: 10) { # How can I handle pagination here?
      id
      body
      author {
        username
      }
      replies(last: 3) { # How can I handle pagination here?
        id
        body
      }
    }
  }
}

How can I handle pagination in those cases? Should I use DataLoader?

Until now, everything that I found on the web suggests using the splice array method, but if I use it, my server will run out of memory, as I should paginate the data on the SQL query, am I right?

So how I am able to query my database with such GraphQL query? Do you handle those cases in any of your projects?

I am really struggling with that. It is even possible to use DataLoader in this case? And if I not use it, I my server will suffer a lot with the N+1 problem...

Contributor guide

Tech stack
javascriptnodejsgraphql
Domain
backendapidatabase
Issue type
research
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
needs investigation
Prerequisites
GraphQL basicsDataLoader fundamentalsSQL pagination conceptsNode.js development
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
35
Research direction
The issue is a question on implementing pagination with DataLoader in GraphQL. The user wants to paginate nested comments and replies efficiently. Review the comments in the issue for suggested solutions, such as using DataLoader with batched SQL queries that include LIMIT and OFFSET or keyset pagination. The repository's documentation and examples (e.g., the 'src/' directory) may also provide patterns. A concrete approach would be to create a DataLoader that loads paginated results per parent, but ensure batching works correctly by passing pagination parameters through the loader's key. The solution may require customizing DataLoader's batch function to handle different pagination arguments.