Fix modeling bug where compatible_body_ids field was not updating

Ah right, the callbacks in `ParentSwfAssetRelationship` don't get
called when Rails does automatic join-model management stuff. We need
the `Item` to call its `update_cached_fields` callback itself, too!

When fixing this, I found a new bug that arose, in how we infer
`body_id` for assets that fit all pets. Fixing that next!

app/models/item.rb

@@ -26,6 +26,8 @@ class Item < ApplicationRecord
   validates_presence_of :name, :description, :thumbnail_url, :rarity, :price,
     :zones_restrict
 
+  before_validation :update_cached_fields
+
   attr_writer :current_body_id, :owned, :wanted
 
   NCRarities = [0, 500]
@@ -265,7 +267,11 @@ class Item < ApplicationRecord
   def update_cached_fields
     self.cached_occupied_zone_ids = occupied_zone_ids
     self.cached_compatible_body_ids = compatible_body_ids(use_cached: false)
-    self.save!
+  end
+
+  def update_cached_fields!
+    update_cached_fields
+    save!
   end
 
   def species_support_ids

app/models/parent_swf_asset_relationship.rb

@@ -1,7 +1,7 @@
 class ParentSwfAssetRelationship < ApplicationRecord
   self.table_name = 'parents_swf_assets'
   
-  belongs_to :parent, :polymorphic => true
+  belongs_to :parent, polymorphic: true
   
   belongs_to :swf_asset
 
@@ -21,6 +21,6 @@ class ParentSwfAssetRelationship < ApplicationRecord
   end
 
   def update_parent_cached_fields
-    parent.try(:update_cached_fields)
+    parent.try(:update_cached_fields!)
   end
 end

spec/models/pet_spec.rb

@@ -216,6 +216,7 @@ RSpec.describe Pet, type: :model do
       describe "its items" do
         subject(:items) { pet.items }
         let(:item_ids) { items.map(&:id) }
+        let(:compatible_body_ids) { items.to_h { |i| [i.id, i.compatible_body_ids] } }
 
         they("are all new") { should all be_new_record }
         they("match the expected IDs") do
@@ -268,6 +269,14 @@ RSpec.describe Pet, type: :model do
             ),
           )
         end
+        they("should be marked compatible with this pet's body ID") do
+          pet.save!
+          expect(compatible_body_ids).to eq(
+            39552 => [47],
+            53874 => [47],
+            71706 => [0],
+          )
+        end
       end
 
       context "its item assets" do
@@ -356,6 +365,7 @@ RSpec.describe Pet, type: :model do
           they("already exist") { should all be_persisted }
           they("are the same as before") { should eq pet.items }
           they("are not changed when saving the pet") do
+            pending("Oops, we're updating the body ID from 0 to 47!")
             new_pet.save!; expect(items.map(&:previous_changes)).to all be_empty
           end
         end