Add paginated_field helper to reduce pagination boilerplate

.gitignore

@@ -6,7 +6,7 @@
 /pkg/
 /spec/reports/
 /tmp/
-/vendor/bundle/
+/vendor/
 
 # rspec failure tracking
 .rspec_status

README.md

@@ -55,6 +55,31 @@ field :fruits, resolver: Resolvers::FruitsResolver
 
 Value returned by query resolver must be a kaminari object or implements its page scope methods (`current_page`, `limit_value`, `total_count`, `total_pages`).
 
+## Paginated Field Helper
+
+For a less verbose way to define paginated fields, use the `paginated_field` helper:
+
+```ruby
+  paginated_field :fruits, Types::FruitType.collection_type, null: true
+
+  def fruits(page: nil, per: nil)
+    ::Fruit.page(page).per(per)
+  end
+```
+
+This automatically adds `page` and `per` arguments (both optional) to the field. You can also add additional arguments using a block:
+
+```ruby
+  paginated_field :fruits, Types::FruitType.collection_type, null: true do
+    argument :where, String, required: false
+    argument :order, String, required: false
+  end
+
+  def fruits(page: nil, per: nil, where: nil, order: nil)
+    ::Fruit.page(page).per(per)
+  end
+```
+
 ## GraphQL query
 
 ```graphql

lib/graphql_pagination.rb

@@ -9,6 +9,8 @@ module GraphqlPagination
 require 'graphql_pagination/collection_type'
 require 'graphql_pagination/collection_metadata_type'
 require 'graphql_pagination/collection_field'
+require 'graphql_pagination/paginated_field'
 
 GraphQL::Schema::Object.extend GraphqlPagination::CollectionType
+GraphQL::Schema::Object.extend GraphqlPagination::PaginatedField
 GraphQL::Schema::Resolver.extend GraphqlPagination::CollectionType

lib/graphql_pagination/paginated_field.rb

@@ -0,0 +1,11 @@
+module GraphqlPagination
+  module PaginatedField
+    def paginated_field(name, type, **, &)
+      field(name, type, **) do
+        argument :page, Integer, required: false
+        argument :per, Integer, required: false
+        instance_eval(&) if block_given?
+      end
+    end
+  end
+end

spec/graphql_pagination/paginated_field_spec.rb

@@ -0,0 +1,134 @@
+RSpec.describe GraphqlPagination::PaginatedField do
+  describe '.paginated_field' do
+    let(:query_type) do
+      Class.new(GraphQL::Schema::Object) do
+        graphql_name 'TestQuery'
+
+        paginated_field :fruits, FruitType.collection_type, null: true
+
+        paginated_field :vegetables, VegetableType.collection_type, null: true do
+          argument :where, String, required: false
+          argument :order, String, required: false
+        end
+
+        def fruits(page: nil, per: nil)
+          FruitModel.all.page(page).per(per)
+        end
+
+        def vegetables(page: nil, per: nil, **)
+          VegetableModel.all.page(page).per(per)
+        end
+      end
+    end
+
+    let(:schema) do
+      query = query_type
+      Class.new(GraphQL::Schema) do
+        query query
+      end
+    end
+
+    it 'defines field with pagination arguments' do
+      field = query_type.fields['fruits']
+      expect(field).not_to be_nil
+      expect(field.arguments.keys).to include('page', 'per')
+    end
+
+    it 'page argument is optional' do
+      field = query_type.fields['fruits']
+      expect(field.arguments['page'].type.non_null?).to be false
+    end
+
+    it 'per argument is optional' do
+      field = query_type.fields['fruits']
+      expect(field.arguments['per'].type.non_null?).to be false
+    end
+
+    context 'with additional arguments in block' do
+      it 'includes additional arguments' do
+        field = query_type.fields['vegetables']
+        expect(field.arguments.keys).to include('page', 'per', 'where', 'order')
+      end
+
+      it 'additional arguments are optional' do
+        field = query_type.fields['vegetables']
+        expect(field.arguments['where'].type.non_null?).to be false
+        expect(field.arguments['order'].type.non_null?).to be false
+      end
+    end
+
+    context 'when used in queries' do
+      subject(:result) { schema.execute(query).to_h['data']['result'] }
+
+      context 'with page and per arguments' do
+        let(:query) do
+          %|{
+            result: fruits(page: 2, per: 2) {
+              collection {
+                id
+                name
+              }
+              metadata {
+                totalCount
+                totalPages
+                limitValue
+                currentPage
+              }
+            }
+          }|
+        end
+
+        it 'executes query successfully' do
+          expect(result['collection'].size).to eq(2)
+          expect(result['metadata']['currentPage']).to eq(2)
+          expect(result['metadata']['limitValue']).to eq(2)
+        end
+      end
+
+      context 'without page and per arguments' do
+        let(:query) do
+          %|{
+            result: fruits {
+              collection {
+                id
+                name
+              }
+              metadata {
+                totalCount
+                totalPages
+                limitValue
+                currentPage
+              }
+            }
+          }|
+        end
+
+        it 'executes query successfully' do
+          expect(result['collection'].size).to eq(11)
+          expect(result['metadata']['currentPage']).to eq(1)
+        end
+      end
+
+      context 'with additional arguments' do
+        let(:query) do
+          %|{
+            result: vegetables(page: 1, per: 5, where: "test") {
+              collection {
+                id
+                name
+              }
+              metadata {
+                totalCount
+              }
+            }
+          }|
+        end
+
+        it 'executes query successfully with additional arguments' do
+          expect(result['collection'].size).to eq(5)
+          expect(result['metadata']['totalCount']).to eq(11)
+        end
+      end
+    end
+  end
+end