Generated migration needs edit to work with uuids.

[david-crowell]

If the tables you're making taggable use uuids rather than integer ids, then in in ActsAsTaggableOnMigration you need to change

t.references :taggable, polymorphic: true

to

t.references :taggable, polymorphic: true, type: :uuid

Otherwise it fails in hilariously non-deterministic ways.

[lmmendes]

I my case I needed to define the tagger also as an uuid type field since I'm using owned tags and the owner (the tagger) has also his primary id key defined as uuid

      t.references :taggable, polymorphic: true, type: :uuid
      t.references :tagger, polymorphic: true, type: :uuid

[bobbytables]

For others using rails 5.2 and are trying to use UUIDs for primary keys, here's what I had to do:

 # This migration comes from acts_as_taggable_on_engine (originally 1)
 if ActiveRecord.gem_version >= Gem::Version.new('5.0')
-  class ActsAsTaggableOnMigration < ActiveRecord::Migration[4.2]; end
+  class ActsAsTaggableOnMigration < ActiveRecord::Migration[5.2]; end
 else
   class ActsAsTaggableOnMigration < ActiveRecord::Migration; end
 end
 ActsAsTaggableOnMigration.class_eval do
   def self.up
-    create_table :tags do |t|
+    create_table :tags, id: :uuid do |t|
       t.string :name
     end

-    create_table :taggings do |t|
+    create_table :taggings, id: :uuid do |t|
-      t.references :tag
+      t.references :tag, type: :uuid

       # You should make sure that the column created is
       # long enough to store the required class names.
-      t.references :taggable, polymorphic: true
-      t.references :tagger, polymorphic: true
+      t.references :taggable, polymorphic: true, type: :uuid
+      t.references :tagger, polymorphic: true, type: :uuid

       # Limit is created to prevent MySQL error on index
       # length for MyISAM table type: http://bit.ly/vgW2Ql
@@ -25,7 +25,6 @@ ActsAsTaggableOnMigration.class_eval do
       t.datetime :created_at
     end

-    add_index :taggings, :tag_id
     add_index :taggings, [:taggable_id, :taggable_type, :context]
   end

[cthorner]

Here is what I did for 4.2: In addition to the other changes(although I didn't remove the :taggings, :tag_id index): I added uuid with this:

create_table :tags, id: false do |t|
      t.uuid :id, null: false, default: 'uuid_generate_v4()', primary_key: true
      t.string :name
    end

    create_table :taggings, id: false do |t|
      t.uuid :id, null: false, default: 'uuid_generate_v4()', primary_key: true
      t.references :tag, type: :uuid