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https://github.com/ulrikstrid/bs-dataloader

Small lib to batch and cache loading of async data, bring your own fetch implementation
https://github.com/ulrikstrid/bs-dataloader

Last synced: 9 months ago
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Small lib to batch and cache loading of async data, bring your own fetch implementation

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# bs-dataloader

[![CircleCI](https://circleci.com/gh/ulrikstrid/bs-dataloader.svg?style=svg)](https://circleci.com/gh/ulrikstrid/bs-dataloader)

This is a rewrite of [dataloader js lib](https://github.com/facebook/dataloader) in reasonml for use with BuckleScript. I have a goal to make it work with native OCaml in the future but I still rely on some JavaScript structures.

## Usage

```ocaml
module UserLoaderImpl = {
type value = user;
type key = userId;

/* The batchLoadFun needs to wrap the returned values in Js.Result.t so that we can reject each promise instead of all */
let batchLoadFun = userIds => batchGetUsers(userIds);
let options: options = {batch: true, maxBatchSize: 256, cache: true};
};

module UserLoader = DataLoader.Make(UserLoaderImpl);

UserLoader.load("1")
|> Js.Promise.then_(
user => {
displayUser user;
Js.Promise.resolve ();
}
);

/* elsewhere in your app */

UserLoader.load("2")
|> Js.Promise.then_(
user => {
interactWithUser user;
Js.Promsie.resolve();
}
);
```

The example above will load both users at the same time with 1 request. If we later need one of the loaded users again we will get a cached version of the promise, if you need a new version from the server you can clear the key.

```ocaml
updateUser(~userId, ~userPatch)
|> Js.Promise.then_(_ => Js.Promise.resolve(UserLoader.clear userId))
|> Js.Promise.then_(_ => UserLoader.load("1"))
|> Js.Promise.then_(user => {
displayUser user;
Js.Promise.resolve ();
});
```

## Development

### Build

```
npm run build
```

### Build + Watch

```
npm run watch
```

### Test

```
npm run test
```

### Editor

If you use `vscode`, Press `Windows + Shift + B` it will build automatically