From 5fc02f00f80e1158c7823b72fd3c46fd15de54fd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Geonizeli?= <joao.geonizeli@gmail.com>
Date: Wed, 11 Aug 2021 21:45:15 -0300
Subject: [PATCH] fix balances query n+1

---
 app/graphql/sources/active_record.rb | 18 ++++++++++++++++++
 app/graphql/types/balance_type.rb    |  6 +++++-
 app/graphql/x_stake_schema.rb        |  1 +
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 app/graphql/sources/active_record.rb

diff --git a/app/graphql/sources/active_record.rb b/app/graphql/sources/active_record.rb
new file mode 100644
index 0000000..09e008a
--- /dev/null
+++ b/app/graphql/sources/active_record.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module Sources
+  class ActiveRecord < GraphQL::Dataloader::Source
+    # rubocop:disable Lint/MissingSuper
+    def initialize(model_class)
+      @model_class = model_class
+    end
+
+    def fetch(ids)
+      @model_class
+        .where(id: ids)
+        .index_by(&:id)
+        .slice(*ids)
+        .values
+    end
+  end
+end
diff --git a/app/graphql/types/balance_type.rb b/app/graphql/types/balance_type.rb
index f1a3e09..8af921f 100644
--- a/app/graphql/types/balance_type.rb
+++ b/app/graphql/types/balance_type.rb
@@ -7,7 +7,11 @@ module Types
     graphql_name "Balance"
 
     field :id, ID, null: false
-    field :currency, CurrencyType, null: false
     field :amount, String, null: false
+
+    field :currency, CurrencyType, null: false
+    def currency
+      dataloader.with(Sources::ActiveRecord, Currency).load(object.currency_id)
+    end
   end
 end
diff --git a/app/graphql/x_stake_schema.rb b/app/graphql/x_stake_schema.rb
index b89bdee..8e5f10d 100644
--- a/app/graphql/x_stake_schema.rb
+++ b/app/graphql/x_stake_schema.rb
@@ -2,6 +2,7 @@
 class XStakeSchema < GraphQL::Schema
   # mutation(Types::MutationType)
   query(Types::QueryType)
+  use GraphQL::Dataloader
 
   def self.resolve_type(abstract_type, obj, ctx)
     case obj