Dataloader

Dataloader provides an easy way efficiently load data in batches. It's inspired by https://github.com/facebook/dataloader, although it makes some small API changes to better suit Elixir use cases.

Installation

The package can be installed by adding :dataloader to your list of dependencies in mix.exs:

def deps do
  [
    {:dataloader, "~> 2.0.0"}
  ]
end

Note: Dataloader requires Elixir 1.10 or higher.

Upgrading

See CHANGELOG for upgrade steps between versions.

Documentation

Dataloader hexdocs.
For the tutorial, guides, and general information about Absinthe-related projects, see http://absinthe-graphql.org.

Usage

Central to Dataloader is the idea of a source. A single Dataloader struct can have many different sources, which represent different ways to load data.

Here's an example of a data loader using an Ecto source, and then loading some organization data.

source = Dataloader.Ecto.new(MyApp.Repo)

# setup the loader
loader = Dataloader.new |> Dataloader.add_source(:db, source)

# load some things
loader =
  loader
  |> Dataloader.load(:db, Organization, 1)
  |> Dataloader.load_many(:db, Organization, [4, 9])

# actually retrieve them
loader = Dataloader.run(loader)

# Now we can get whatever values out we want
organizations = Dataloader.get_many(loader, :db, Organization, [1,4])

This will do a single SQL query to get all organizations by ids 1, 4, and 9. You can load multiple batches from multiple sources, and then when run/1 is called batch will be loaded concurrently.

Here we named the source :db within our dataloader. More commonly though if you're using Phoenix you'll want to name it after one of your contexts, and have a different source used for each context. This provides an easy way to enforce data access rules within each context. See the Dataloader.Ecto moduledocs for more details

Sources

Dataloader ships with two different built in sources. The first is the Ecto source for easily pulling out data with ecto. The other is a simple KV key value source. See each module for its respective documentation.

Anything that implements the Dataloader.Source protocol can act as a source.

Community

The project is under constant improvement by a growing list of contributors, and your feedback is important. Please join us in Slack (#absinthe-graphql under the Elixir Slack account) or the Elixir Forum (tagged absinthe).

Please remember that all interactions in our official spaces follow our Code of Conduct.

Related Projects

See the GitHub organization.

Contributing

Please follow contribution guide.

License

See LICENSE.md.

absinthe-graphql/dataloader