add: project explore api

db/migrate/20211027032626_add_some_columns_to_project_detail_feature.rb

@@ -0,0 +1,7 @@
+class AddSomeColumnsToProjectDetailFeature < ActiveRecord::Migration[5.2]
+  def change
+    add_column :project_categories, :pinned_index, :integer, default: 0
+    add_column :projects, :is_pinned, :boolean, default: false
+    add_column :projects, :recommend_index, :integer, default: 0
+  end
+end