https://github.com/andreas/ocaml-dataloader

Dataloader is a utility for batching and caching when fetching data, in particular for GraphQL.
https://github.com/andreas/ocaml-dataloader

graphql

Last synced: about 2 months ago
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Dataloader is a utility for batching and caching when fetching data, in particular for GraphQL.

• Host: GitHub
• URL: https://github.com/andreas/ocaml-dataloader
• Owner: andreas
• Created: 2017-12-01T21:34:04.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2019-12-02T05:53:53.000Z (almost 5 years ago)
• Last Synced: 2024-05-11T22:33:06.964Z (4 months ago)
• Topics: graphql
• Language: OCaml
• Homepage:
• Size: 4.88 KB
• Stars: 44
• Watchers: 4
• Forks: 5
• Open Issues: 2
• Metadata Files:
  • Readme: README.md

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README

        
Dataloader is a utility to be used for your application's data fetching layer to provide batching and caching, in particular with [`ocaml-graphql-server`](https://github.com/andreas/ocaml-graphql-server). It is a port of [facebook/dataloader](https://github.com/facebook/dataloader) for Node. The library is still under active development.

This repo contains two packages:

- `dataloader`, which is IO-agnostic written in CPS-style.

- `dataloader-lwt`, which is a shim on top of `dataloader` for [`Lwt`](https://github.com/ocsigen/lwt).

## Example

The following examples assumes a function `batchLoadUsersFromDatabase` of the type `user_id list -> (user list, exn) result Lwt.t`:

```ocaml

let user_loader = Dataloader_lwt.create ~load:(fun user_ids ->

  batchLoadUsersFromDatabase user_ids

)

(* triggers only 1 query rather than 5 *)

List.map (fun user_id ->

  Dataloader_lwt.load user_loader user_id

) [1; 2; 3; 4; 5]

```

The function `~load` provided to `Dataloader.create` must uphold the following constraints:

- The list of values must be the same length as the list of keys.

- Each index in the list of values must correspond to the same index in the list of keys.