From 0cd3cc6780217dc05a4131522a03f9569d73e8cc Mon Sep 17 00:00:00 2001
From: Jon Jensen <jenseng@gmail.com>
Date: Sat, 21 Nov 2015 09:46:25 -0700
Subject: [PATCH] bring `dependent: nullify` along to add_foreign_key, fixes
 #24

---
 lib/immigrant.rb       | 13 ++++++++++---
 test/immigrant_test.rb | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/lib/immigrant.rb b/lib/immigrant.rb
index ff6b3cd..bd00647 100644
--- a/lib/immigrant.rb
+++ b/lib/immigrant.rb
@@ -75,7 +75,7 @@ def model_keys(classes)
           #    Foo.has_many :bars
           #    Foo.has_many :bazzes, :class_name => Bar
           # we need to make sure everything is legit and see if any of them
-          # specify :dependent => :delete
+          # specify :dependent => :delete|:delete_all|:nullify
           if current_key = foreign_keys[foreign_key.hash_key]
             if current_key.to_table != foreign_key.to_table || current_key.options[:primary_key] != foreign_key.options[:primary_key]
               warnings[foreign_key.hash_key] ||= "Skipping #{foreign_key.from_table}.#{foreign_key.options[:column]}: it has multiple associations referencing different keys/tables."
@@ -149,6 +149,12 @@ def infer_belongs_to_keys(klass, reflection)
         ]
       end
 
+      DEPENDENT_MAP = {
+        :delete => :cascade,
+        :delete_all => :cascade,
+        :nullify => :nullify
+      }
+
       def infer_has_n_keys(klass, reflection)
         from_table = reflection.klass.table_name
         to_table = klass.table_name
@@ -156,8 +162,9 @@ def infer_has_n_keys(klass, reflection)
         primary_key = (reflection.options[:primary_key] || klass.primary_key).to_s
 
         actions = {}
-        if [:delete, :delete_all].include?(reflection.options[:dependent]) && !qualified_reflection?(reflection, klass)
-          actions = {:on_delete => :cascade, :on_update => :cascade}
+        dependent_action = DEPENDENT_MAP[reflection.options[:dependent]]
+        if dependent_action && !qualified_reflection?(reflection, klass)
+          actions = {:on_delete => dependent_action, :on_update => dependent_action}
         end
 
         [
diff --git a/test/immigrant_test.rb b/test/immigrant_test.rb
index a0c60e4..feecb36 100644
--- a/test/immigrant_test.rb
+++ b/test/immigrant_test.rb
@@ -143,6 +143,23 @@ class Book < ActiveRecord::Base; end
     )
   end
 
+  test 'has_one :dependent => :nullify should generate a foreign key with :on_delete => :nullify' do
+    given <<-CODE
+      class Author < ActiveRecord::Base
+        has_one :book, :order => "id DESC", :dependent => :nullify
+      end
+      class Book < ActiveRecord::Base; end
+    CODE
+
+    assert_equal(
+      [foreign_key_definition(
+         'books', 'authors',
+         :column => 'author_id', :primary_key => 'id', :on_delete => :nullify, :on_update => :nullify
+       )],
+      infer_keys
+    )
+  end
+
   test 'has_many should generate a foreign key' do
     given <<-CODE
       class Author < ActiveRecord::Base
@@ -177,6 +194,23 @@ class Book < ActiveRecord::Base; end
     )
   end
 
+  test 'has_many :dependent => :nullify should generate a foreign key with :on_delete => :nullify' do
+    given <<-CODE
+      class Author < ActiveRecord::Base
+        has_many :books, :dependent => :nullify
+      end
+      class Book < ActiveRecord::Base; end
+    CODE
+
+    assert_equal(
+      [foreign_key_definition(
+         'books', 'authors',
+         :column => 'author_id', :primary_key => 'id', :on_delete => :nullify, :on_update => :nullify
+       )],
+      infer_keys
+    )
+  end
+
   test 'has_and_belongs_to_many should generate two foreign keys' do
     given <<-CODE
       class Author < ActiveRecord::Base