Add field mergeRequests for project in GraphQL

And fix the tests so that it won't run into circular paths.

4 files changed, 32 insertions, 6 deletions

diff --git a/app/graphql/mutations/merge_requests/base.rb b/app/graphql/mutations/merge_requests/base.rb
index 54f01c99d78..7d0cb777ad1 100644
--- a/app/graphql/mutations/merge_requests/base.rb
+++ b/app/graphql/mutations/merge_requests/base.rb
@@ -25,7 +25,8 @@ module Mutations
 
       def find_object(project_path:, iid:)
         project = resolve_project(full_path: project_path)
-        resolver = Resolvers::MergeRequestResolver.new(object: project, context: context)
+        resolver = Resolvers::MergeRequestsResolver
+          .single.new(object: project, context: context)
 
         resolver.resolve(iid: iid)
       end
diff --git a/app/graphql/resolvers/base_resolver.rb b/app/graphql/resolvers/base_resolver.rb
index 459933af9d3..063def75d38 100644
--- a/app/graphql/resolvers/base_resolver.rb
+++ b/app/graphql/resolvers/base_resolver.rb
@@ -2,5 +2,12 @@
 
 module Resolvers
   class BaseResolver < GraphQL::Schema::Resolver
+    def self.single
+      @single ||= Class.new(self) do
+        def resolve(**args)
+          super.first
+        end
+      end
+    end
   end
 end
diff --git a/app/graphql/resolvers/merge_request_resolver.rb b/app/graphql/resolvers/merge_requests_resolver.rb
index d047ce9e3a1..15055db633a 100644
--- a/app/graphql/resolvers/merge_request_resolver.rb
+++ b/app/graphql/resolvers/merge_requests_resolver.rb
@@ -1,19 +1,30 @@
 # frozen_string_literal: true
 
 module Resolvers
-  class MergeRequestResolver < BaseResolver
+  class MergeRequestsResolver < BaseResolver
     argument :iid, GraphQL::ID_TYPE,
-             required: true,
+             required: false,
              description: 'The IID of the merge request, e.g., "1"'
 
+    argument :iids, [GraphQL::ID_TYPE],
+              required: false,
+              description: 'The list of IIDs of issues, e.g., [1, 2]'
+
     type Types::MergeRequestType, null: true
 
     alias_method :project, :object
 
-    # rubocop: disable CodeReuse/ActiveRecord
-    def resolve(iid:)
+    def resolve(**args)
       return unless project.present?
 
+      args[:iids] ||= [args[:iid]]
+
+      args[:iids].map(&method(:batch_load))
+        .select(&:itself) # .compact doesn't work on BatchLoader
+    end
+
+    # rubocop: disable CodeReuse/ActiveRecord
+    def batch_load(iid)
       BatchLoader.for(iid.to_s).batch(key: project) do |iids, loader, args|
         args[:key].merge_requests.where(iid: iids).each do |mr|
           loader.call(mr.iid.to_s, mr)
diff --git a/app/graphql/types/project_type.rb b/app/graphql/types/project_type.rb
index 050706f97be..daced8af1c2 100644
--- a/app/graphql/types/project_type.rb
+++ b/app/graphql/types/project_type.rb
@@ -66,10 +66,17 @@ module Types
     field :only_allow_merge_if_all_discussions_are_resolved, GraphQL::BOOLEAN_TYPE, null: true
     field :printing_merge_request_link_enabled, GraphQL::BOOLEAN_TYPE, null: true
 
+    field :merge_requests,
+          Types::MergeRequestType.connection_type,
+          null: true,
+          resolver: Resolvers::MergeRequestsResolver do
+      # authorize :read_merge_request
+    end
+
     field :merge_request,
           Types::MergeRequestType,
           null: true,
-          resolver: Resolvers::MergeRequestResolver do
+          resolver: Resolvers::MergeRequestsResolver.single do
       authorize :read_merge_request
     end