graphql/dataloader

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

Open

#231 opened on Dec 5, 2019

View on GitHub
 (20 comments) (8 reactions) (0 assignees)JavaScript (556 forks)batch import
help wanted

Repository metrics

Stars
 (12,520 stars)
PR merge metrics
 (Avg merge 5d 2h) (1 merged PR in 30d)

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

Research direction
Investigate how to implement pagination with DataLoader by batching paginated queries. Start with a DataLoader that accepts pagination arguments and returns batched results. Consider using keys like `${parentId}:${cursor}:${limit}`. Read the DataLoader documentation and examples on batch functions. Look into offset based vs. cursor based pagination and how to combine with batching. Ask for specific implementation patterns in the issue thread.
Tech stack
javascriptgraphql
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.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
JavaScriptGraphQLDataLoaderSQL
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60