Use per_page based on model by default

Author: JiriChara

lib/api-pagination.rb

@@ -45,22 +45,42 @@ def paginate_with_kaminari(collection, options, paginate_array_options = {})
       if Kaminari.config.max_per_page && options[:per_page] > Kaminari.config.max_per_page
         options[:per_page] = Kaminari.config.max_per_page
       elsif options[:per_page] <= 0
-        options[:per_page] = Kaminari.config.default_per_page
+        options[:per_page] = get_default_per_page_for_kaminari(collection)
       end
 
       collection = Kaminari.paginate_array(collection, paginate_array_options) if collection.is_a?(Array)
       collection.page(options[:page]).per(options[:per_page])
     end
 
     def paginate_with_will_paginate(collection, options)
-      options[:per_page] = WillPaginate.per_page if options[:per_page] <= 0
+      if options[:per_page] <= 0
+        options[:per_page] = default_per_page_for_will_paginate(collection)
+      end
 
       if defined?(Sequel::Dataset) && collection.kind_of?(Sequel::Dataset)
         collection.paginate(options[:page], options[:per_page])
       else
         collection.paginate(:page => options[:page], :per_page => options[:per_page])
       end
     end
+
+    def get_default_per_page_for_kaminari(collection)
+      default = Kaminari.config.default_per_page
+      detect_model(collection).default_per_page || default
+    rescue
+      default
+    end
+
+    def default_per_page_for_will_paginate(collection)
+      default = WillPaginate.per_page
+      detect_model(collection).per_page || default
+    rescue
+      default
+    end
+
+    def detect_model(collection)
+      collection.first.class
+    end
   end
 end
 

spec/rails_spec.rb

@@ -200,5 +200,47 @@
         end
       end
     end
+
+    context 'default per page in model' do
+      before do
+        class Fixnum
+          @default_per_page = 6
+          @per_page = 6
+
+          class << self
+            attr_accessor :default_per_page, :per_page
+          end
+        end
+      end
+
+      after do
+        class Fixnum
+          @default_per_page = 25
+          @per_page = 25
+        end
+      end
+
+      it 'should use default per page from model' do
+        get :index_with_no_per_page, count: 100
+
+        expect(response.header['Per-Page']).to eq('6')
+      end
+
+      it 'should not fail if model does not respond to per page' do
+        class Fixnum
+          @default_per_page = nil
+          @per_page = nil
+        end
+
+        get :index_with_no_per_page, count: 100
+
+        expect(response.header['Per-Page']).to eq(
+          case ApiPagination.config.paginator
+          when :kaminari      then Kaminari.config.default_per_page.to_s
+          when :will_paginate then WillPaginate.per_page.to_s
+          end
+        )
+      end
+    end
   end
 end