1 files changed, 43 insertions, 0 deletions
diff --git a/app/graphql/resolvers/user_resolver.rb b/app/graphql/resolvers/user_resolver.rb
new file mode 100644
index 00000000000..a34cecba491
--- /dev/null
+++ b/app/graphql/resolvers/user_resolver.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Resolvers
+  class UserResolver < BaseResolver
+    description 'Retrieve a single user'
+
+    type Types::UserType, null: true
+
+    argument :id, GraphQL::ID_TYPE,
+             required: false,
+             description: 'ID of the User'
+
+    argument :username, GraphQL::STRING_TYPE,
+             required: false,
+             description: 'Username of the User'
+
+    def ready?(id: nil, username: nil)
+      unless id.present? ^ username.present?
+        raise Gitlab::Graphql::Errors::ArgumentError, 'Provide either a single username or id'
+      end
+
+      super
+    end
+
+    def resolve(id: nil, username: nil)
+      if id
+        GitlabSchema.object_from_id(id, expected_type: User)
+      else
+        batch_load(username)
+      end
+    end
+
+    private
+
+    def batch_load(username)
+      BatchLoader::GraphQL.for(username).batch do |usernames, loader|
+        User.by_username(usernames).each do |user|
+          loader.call(user.username, user)
+        end
+      end
+    end
+  end
+end