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Implementation of Facebook's DataLoader in Golang
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Fixed module name in README
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LICENSE add name and year to licence Dec 15, 2016 Adding migration guide Apr 11, 2018 opencensus trace example (#58) Jul 26, 2019
cache.go Implement `Key` interface for V5 Jan 4, 2018
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dataloader.go Fix typos (#48) Feb 27, 2019
dataloader_test.go Implement `Key` interface for V5 Jan 4, 2018
inMemoryCache.go Fix typos (#48) Feb 27, 2019
inMemoryCache_go19.go Fix typos (#48) Feb 27, 2019
key.go Fix typos (#48) Feb 27, 2019
trace.go Implement `Key` interface for V5 Jan 4, 2018


GoDoc Build Status

This is an implementation of Facebook's DataLoader in Golang.


go get -u


// setup batch function
batchFn := func(ctx context.Context, keys dataloader.Keys) []*dataloader.Result {
  var results []*dataloader.Result
  // do some async work to get data for specified keys
  // append to this list resolved values
  return results

// create Loader with an in-memory cache
loader := dataloader.NewBatchedLoader(batchFn)

 * Use loader
 * A thunk is a function returned from a function that is a
 * closure over a value (in this case an interface value and error).
 * When called, it will block until the value is resolved.
thunk := loader.Load(context.TODO(), dataloader.StringKey("key1")) // StringKey is a convenience method that make wraps string to implement `Key` interface
result, err := thunk()
if err != nil {
  // handle data error

log.Printf("value: %#v", result)

Don't need/want to use context?

You're welcome to install the v1 version of this library.


This implementation contains a very basic cache that is intended only to be used for short lived DataLoaders (i.e. DataLoaders that ony exsist for the life of an http request). You may use your own implementation if you want.

it also has a NoCache type that implements the cache interface but all methods are noop. If you do not wish to cache anything.


There are a few basic examples in the example folder.

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