Code snippets for Dataloader Blog

leslie_1_query.graphql

query Leslie {
  employee(id: "1000") {
    name
    office {
      name
      url
    }
  }
}

leslie_1_response.json

{
  "data": {
    "employee": {
      "name": "Leslie Knope",
      "office": {
        "name": "Parks and Recreation",
        "url": "https://pawnee.gov/parks_and_rec"
      }
    }
  }
}

leslie_2_query.graphql

query LesliesDirectReports {
  employee(id:"1000") {
    name
    directReports {
      name
    }
  }
}

leslie_2_response.json

{
  "data": {
    "employee": {
      "name": "Leslie Knope",
      "directReports": [
        {
          "name": "Andy Dwyer"
        },
        {
          "name": "April Ludgate"
        },
        {
          "name": "Tom Haverford"
        }
      ]
    }
  }
}

leslie_3_query.graphql

query LesliesDirectReportsWithOffices {
  employee(id:"1000") {
    name
    office {
      name
      url
    }
    directReports {
      name
      office {
        name
        url
      }
    }
  }
}

leslie_4_response.json

{
  "data": {
    "employee": {
      "name": "Leslie Knope",
      "office": {
        "name": "Parks and Recreation",
        "url": "https://pawnee.gov/parks_and_rec"
      },
      "directReports": [
        {
          "name": "Andy Dwyer",
          "office": {
            "name": "Parks and Recreation",
            "url": "https://pawnee.gov/parks_and_rec"
          }
        },
        {
          "name": "April Ludgate",
          "office": {
            "name": "Parks and Recreation",
            "url": "https://pawnee.gov/parks_and_rec"
          }
        },
        {
          "name": "Tom Haverford",
          "office": {
            "name": "Parks and Recreation",
            "url": "https://pawnee.gov/parks_and_rec"
          }
        }
      ]
    }
  }
}

resolver_1.ex

  @doc """
  Resolver for the Employee 'office' field.
  """
  @spec office_for_employee(map(), map(), Absinthe.Resolution.t()) :: tuple()
  def office_for_employee(employee, args, resolution)

  def office_for_employee(%{office_id: office_id}, _, _) do
    office = Core.office_by_id(office_id)
    {:ok, office}
  end

resolver_2.ex

  @doc """
  Resolver for the Employee 'office' field.
  """
  @spec office_for_employee(map(), map(), Absinthe.Resolution.t()) :: tuple()
  def office_for_employee(employee, args, resolution)

  def office_for_employee(%{office_id: office_id}, _, %{context: %{loader: loader}}) do
    loader
    |> Dataloader.load(Core, :office_by_id, office_id)
    |> on_load(fn loader ->
      office = Dataloader.get(loader, Core, :office_by_id, office_id)
      {:ok, office}
    end)
  end