Apollo Query Batching and graphql-ruby

Query batching is a way to speed up your application. Instead of waiting on multiple client-server roundtrips to load data, everything is loaded at once.

Enabling query batching in Apollo is as easy as using another network provider:

  import ApolloClient, { createBatchingNetworkInterface } from 'apollo-client';
  const batchingNetworkInterface = createBatchingNetworkInterface({
    uri: 'localhost:3000',
    batchInterval: 10,  // in milliseconds
    batchMax: 10,
    opts: {
      // Options to pass along to `fetch`
    }
  });
  const apolloClient = new ApolloClient({
    networkInterface: batchingNetworkInterface,
  });

On the Ruby you need to make a few more changes, but all can be done in your GraphQL Controller. You need to map the array of given queries to a format that graphql-ruby understands. The gist below handles both batched and non-batched queries.

def execute
  context = {}

  # Apollo sends the params in a _json
  # variable when batching is enabled
  # see the Apollo Documentation about query batching:
  # http://dev.apollodata.com/core/network.html#query-batching
  result = if params[:_json]
    queries = params[:_json].map do |param|
      {
        query: param['query'],
        operation_name: param['operationName'],
        variables: ensure_hash(param['variables']),
        context: context
      }
    end
    MySchema.multiplex(queries)
  else
    MySchema.execute(
      params[:query],
      operation_name: params[:operationName],
      variables: ensure_hash(params[:variables]),
      context: context
    )
  end

  render json: result
end

Batching queries can reduce the time your app is loading by a large amount, making for a more pleasant user experience.