Merge pull request #284 from abicky/consider-table-dependency

Drop tables in an order considering foreign key constraints

lib/ridgepole/delta.rb

@@ -42,7 +42,7 @@ def script
         append_change(table_name, attrs, buf, pre_buf_for_fk, post_buf_for_fk)
       end
 
-      (@delta[:delete] || {}).each do |table_name, attrs|
+      (@delta[:delete] || {}).reverse_each do |table_name, attrs|
         append_drop_table(table_name, attrs, buf)
       end
 

lib/ridgepole/dsl_parser.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'tsort'
+
 module Ridgepole
   class DSLParser
     def initialize(options = {})
@@ -10,7 +12,11 @@ def parse(dsl, opts = {})
       definition, execute = Context.eval(dsl, opts)
       check_orphan_index(definition)
       check_orphan_foreign_key(definition)
-      [definition, execute]
+      sorted_definition = {}
+      DependencyGraph.new(definition).tsort_each do |table_name|
+        sorted_definition[table_name] = definition[table_name]
+      end
+      [sorted_definition, execute]
     end
 
     private
@@ -26,5 +32,22 @@ def check_orphan_foreign_key(definition)
         raise "Table `#{table_name}` to create the foreign key is not defined: #{attrs[:foreign_keys].keys.join(',')}" if attrs[:foreign_keys] && !(attrs[:definition])
       end
     end
+
+    class DependencyGraph
+      include TSort
+
+      def initialize(definition)
+        @definition = definition
+      end
+
+      def tsort_each_child(table_name, &block)
+        keys = @definition[table_name].fetch(:foreign_keys, {})
+        keys.each_value { |v| block.call(v[:to_table]) }
+      end
+
+      def tsort_each_node(&block)
+        @definition.each_key(&block)
+      end
+    end
   end
 end

spec/mysql/fk/migrate_drop_fk_spec.rb

@@ -60,29 +60,29 @@
   context 'when drop fk when drop table' do
     let(:dsl) do
       erbh(<<-ERB)
-        create_table "parent", <%= i cond('>= 5.1',id: :integer) %>, force: :cascade do |t|
+        create_table "0_parent", <%= i cond('>= 5.1',id: :integer) %>, force: :cascade do |t|
         end
 
-        create_table "child", force: :cascade do |t|
-          t.integer "parent_id"
-          t.index ["parent_id"], name: "par_id", <%= i cond(5.0, using: :btree) %>
+        create_table "1_child", force: :cascade do |t|
+          t.integer "0_parent_id"
+          t.index ["0_parent_id"], name: "par_id", <%= i cond(5.0, using: :btree) %>
         end
 
-        add_foreign_key "child", "parent", name: "child_ibfk_1"
+        add_foreign_key "1_child", "0_parent", name: "child_ibfk_1"
       ERB
     end
 
     let(:sorted_dsl) do
       erbh(<<-ERB)
-        create_table "child", force: :cascade do |t|
-          t.integer "parent_id"
-          t.index ["parent_id"], name: "par_id", <%= i cond(5.0, using: :btree) %>
+        create_table "0_parent", <%= i cond('>= 5.1',id: :integer) %>, force: :cascade do |t|
         end
 
-        create_table "parent", <%= i cond('>= 5.1',id: :integer) %>, force: :cascade do |t|
+        create_table "1_child", force: :cascade do |t|
+          t.integer "0_parent_id"
+          t.index ["0_parent_id"], name: "par_id", <%= i cond(5.0, using: :btree) %>
         end
 
-        add_foreign_key "child", "parent", name: "child_ibfk_1"
+        add_foreign_key "1_child", "0_parent", name: "child_ibfk_1"
       ERB
     end