From absinthe-graphql
Guides GraphQL resolver implementation in Absinthe with patterns, Dataloader integration for N+1 prevention, batching, middleware, context, and error handling.
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/absinthe-graphql:absinthe-resolversThe summary Claude sees in its skill listing — used to decide when to auto-load this skill
Guide to implementing efficient and maintainable resolvers in Absinthe.
Guide to implementing efficient and maintainable resolvers in Absinthe.
defmodule MyApp.Resolvers.User do
alias MyApp.Accounts
def list_users(_parent, args, _resolution) do
{:ok, Accounts.list_users(args)}
end
def get_user(_parent, %{id: id}, _resolution) do
case Accounts.get_user(id) do
nil -> {:error, "User not found"}
user -> {:ok, user}
end
end
def create_user(_parent, %{input: input}, _resolution) do
case Accounts.create_user(input) do
{:ok, user} -> {:ok, user}
{:error, changeset} -> {:error, changeset}
end
end
end
def current_user(_parent, _args, %{context: %{current_user: user}}) do
{:ok, user}
end
def current_user(_parent, _args, _resolution) do
{:error, "Not authenticated"}
end
defmodule MyApp.Schema do
use Absinthe.Schema
def context(ctx) do
loader =
Dataloader.new()
|> Dataloader.add_source(MyApp.Repo, Dataloader.Ecto.new(MyApp.Repo))
Map.put(ctx, :loader, loader)
end
def plugins do
[Absinthe.Middleware.Dataloader] ++ Absinthe.Plugin.defaults()
end
end
# In type definitions
object :user do
field :posts, list_of(:post) do
resolve dataloader(MyApp.Repo)
end
end
defmodule MyApp.Loaders.User do
def data() do
Dataloader.KV.new(&fetch/2)
end
defp fetch(:posts_count, user_ids) do
counts = MyApp.Posts.count_by_user_ids(user_ids)
Map.new(user_ids, fn id ->
{id, Map.get(counts, id, 0)}
end)
end
end
defmodule MyApp.Middleware.Auth do
@behaviour Absinthe.Middleware
def call(resolution, _config) do
case resolution.context do
%{current_user: %{}} ->
resolution
_ ->
resolution
|> Absinthe.Resolution.put_result({:error, "Unauthorized"})
end
end
end
# Apply to fields
field :admin_data, :string do
middleware MyApp.Middleware.Auth
resolve &MyApp.Resolvers.Admin.get_data/3
end
defmodule MyApp.Resolvers.Helpers do
def handle_changeset_errors(%Ecto.Changeset{} = changeset) do
errors =
Ecto.Changeset.traverse_errors(changeset, fn {msg, opts} ->
Enum.reduce(opts, msg, fn {key, value}, acc ->
String.replace(acc, "%{#{key}}", to_string(value))
end)
end)
{:error, errors}
end
end
npx claudepluginhub thebushidocollective/han --plugin absinthe-graphqlImplements GraphQL resolvers covering function signatures, field resolvers, context management, DataLoader batching, error handling, authentication, and testing strategies.
Guides designing GraphQL schemas with Absinthe in Elixir. Covers type definitions, interfaces, unions, enums, input objects, schema organization, custom scalars, and best practices.
Structures GraphQL resolvers with clean separation between data fetching, business logic, and response shaping. Guides context setup, field resolvers, and domain-based file organization.