Add support foreign key constraints

lib/yaml_db/serialization_helper.rb

@@ -164,8 +164,49 @@ def self.after_table(io, table)
 
       end
 
+      def self.class_exists?(class_name)
+        klass = Module.const_get(class_name)
+        return klass.is_a?(Class)
+      rescue NameError
+        return false
+      end
+
       def self.tables
-        ActiveRecord::Base.connection.tables.reject { |table| ['schema_info', 'schema_migrations'].include?(table) }.sort
+        tables = ActiveRecord::Base.connection.tables.reject do |table|
+          ['schema_info', 'schema_migrations'].include?(table)
+        end
+        result_tables = tables.select do |table|
+          !class_exists?(table.classify)
+        end
+        tables -= result_tables
+        sort_tables = Array.new
+        while tables.length > 0
+          tables.delete_if do |table|
+            table_class = table.classify.constantize
+
+            find_undefined = table_class.reflect_on_all_associations(:belongs_to).find do |reflection|
+              if reflection.options.include?(:class_name)
+                reflection_table_name = reflection.options[:class_name].constantize.table_name
+
+                if reflection_table_name != table
+                  !sort_tables.include?(reflection.options[:class_name].constantize.table_name)
+                else
+                  false
+                end
+              else
+                !sort_tables.include?(reflection.name.to_s.classify.constantize.table_name)
+              end
+            end
+
+            if find_undefined
+              false
+            else
+              sort_tables << table
+              true
+            end
+          end
+        end
+        sort_tables + result_tables
       end
 
       def self.dump_table(io, table)
@@ -179,7 +220,6 @@ def self.table_column_names(table)
         ActiveRecord::Base.connection.columns(table).map { |c| c.name }
       end
 
-
       def self.each_table_page(table, records_per_page=1000)
         total_count = table_record_count(table)
         pages = (total_count.to_f / records_per_page).ceil - 1

yaml_db.gemspec

@@ -19,7 +19,7 @@ Gem::Specification.new do |s|
 
   s.required_ruby_version = ">= 1.8.7"
 
-  s.add_runtime_dependency "rails", ">= 3.0", "< 5.2"
+  s.add_runtime_dependency "rails", ">= 3.0"
   s.add_runtime_dependency "rake", ">= 0.8.7"
 
   s.add_development_dependency "bundler", "~> 1.14"