Properly handle lists of input objects as directive arguments

Author: rmosolgo

lib/graphql/schema/directive.rb

@@ -129,11 +129,22 @@ def initialize(owner, **arguments)
         # not runtime arguments.
         context = Query::NullContext.instance
         self.class.all_argument_definitions.each do |arg_defn|
-          if arguments.key?(arg_defn.keyword)
-            value = arguments[arg_defn.keyword]
+          keyword = arg_defn.keyword
+          arg_type = arg_defn.type
+          if arguments.key?(keyword)
+            value = arguments[keyword]
             # This is a Ruby-land value; convert it to graphql for validation
             graphql_value = begin
-              arg_defn.type.unwrap.coerce_isolated_result(value)
+              coerce_value = value
+              if arg_type.list? && (!coerce_value.nil?) && (!coerce_value.is_a?(Array))
+                # When validating inputs, GraphQL accepts a single item
+                # and implicitly converts it to a one-item list.
+                # However, we're using result coercion here to go from Ruby value
+                # to GraphQL value, so it doesn't have that feature.
+                # Keep the GraphQL-type behavior but implement it manually:
+                coerce_value = [coerce_value]
+              end
+              arg_type.coerce_isolated_result(coerce_value)
             rescue GraphQL::Schema::Enum::UnresolvedValueError
               # Let validation handle this
               value
@@ -142,7 +153,7 @@ def initialize(owner, **arguments)
             value = graphql_value = nil
           end
 
-          result = arg_defn.type.validate_input(graphql_value, context)
+          result = arg_type.validate_input(graphql_value, context)
           if !result.valid?
             raise InvalidArgumentError, "@#{graphql_name}.#{arg_defn.graphql_name} on #{owner.path} is invalid (#{value.inspect}): #{result.problems.first["explanation"]}"
           end

spec/graphql/schema/directive_spec.rb

@@ -12,6 +12,15 @@ class MultiWord < GraphQL::Schema::Directive
   module DirectiveTest
     class Secret < GraphQL::Schema::Directive
       argument :top_secret, Boolean
+      class PermissionRule < GraphQL::Schema::InputObject
+        class Permission < GraphQL::Schema::Enum
+          value :READ
+          value :WRITE
+        end
+        argument :team, String
+        argument :permission, Permission
+      end
+      argument :permission_rules, [PermissionRule], required: false
       locations(FIELD_DEFINITION, ARGUMENT_DEFINITION)
     end
 
@@ -22,6 +31,13 @@ class Thing < GraphQL::Schema::Object
           directive Secret, top_secret: false
         end
       end
+
+      field :other_info, String do
+        directive Secret, top_secret: false, permission_rules: [
+          { team: "admins", permission: "WRITE" },
+          { team: "others", permission: "READ"},
+        ]
+      end
     end
   end
 
@@ -36,6 +52,12 @@ class Thing < GraphQL::Schema::Object
     assert_equal [DirectiveTest::Secret], argument.directives.map(&:class)
     assert_equal [argument], argument.directives.map(&:owner)
     assert_equal [false], argument.directives.map{ |d| d.arguments[:top_secret] }
+
+    other_field = DirectiveTest::Thing.fields.values.last
+    other_field_dir = other_field.directives.first
+    perm_roles = other_field_dir.arguments[:permission_rules]
+    assert_equal Array.new(2, DirectiveTest::Secret::PermissionRule), perm_roles.map(&:class)
+    assert_equal ["WRITE", "READ"], perm_roles.map(&:permission)
   end
 
   it "raises an error when added to the wrong thing" do