Rails 4: can't update polymorphic nested resource through form - ruby-on-rails

Question

Just in the final stages of transferring an app stuck in Rails 2 on a shared server to Rails 4 on a VPS, but stuck on one thing.
I have an Image model that uses Carrierwave to upload and display attached images. The Image model has a polymorphic association to a couple of other models. The host and associated models are updated together on a combined multipart form.
The form works perfectly well for creating and editing the primary model and for creating and attaching new images, but the image attributes can't be edited, and no error is thrown to help.
Here are the relevant parts of my Image model:
class Image < ActiveRecord::Base
belongs_to :imagings, polymorphic: true, touch: true
mount_uploader :image, ImageUploader, mount_on: :image_file_name
end
And my Review model:
class Review < ActiveRecord::Base
has_many :images, as: :imagings, dependent: :destroy
accepts_nested_attributes_for :images, reject_if: lambda { |t| t['image'].nil? }, allow_destroy: true
end
And my Reviews Controller:
class ReviewsController < ApplicationController
def edit
#review = Review.find(params[:id])
3.times {#review.images.build}
end
def update
#review = Review.find(params[:id])
if #review.update(reviews_params)
redirect_to #review, notice: "Successfully updated review."
else
render :edit
end
end
private
def reviews_params
params.require(:review).permit(:title, :authors, :venue, :startdate, :enddate, :body, :approved, :company, :user_id, { images_attributes: [:title, :credits, :image, :_destroy, :id] })
end
end
I can add images to existing reviews or to a new review perfectly well with this setup, but if I try to change text fields for an existing image, the parameters show in the console but they are ignored:
Started PATCH "/reviews/492" for 127.0.0.1 at 2014-07-16 11:03:42 +0100
Processing by ReviewsController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"HvrsCAXXvO4zIqTBw05qSUwU9I2241DXyilhswEbU9o=", "review"=>{"title"=>"Here's a new review", "authors"=>"", "company"=>"", "venue"=>"", "startdate"=>"2014-07-16", "enddate"=>"2014-07-31", "body"=>"<p>Something</p>", "images_attributes"=>{"0"=>{"title"=>"Doggie", "credits"=>"Icons galore", "_destroy"=>"0", "id"=>"1239"}, "1"=>{"title"=>"", "credits"=>""}, "2"=>{"title"=>"", "credits"=>""}, "3"=>{"title"=>"", "credits"=>""}}, "user_id"=>"4", "approved"=>"1"}, "commit"=>"Update Review", "id"=>"492"}
User Load (0.4ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1 [["id", 1]]
Review Load (0.3ms) SELECT "reviews".* FROM "reviews" WHERE "reviews"."id" = $1 LIMIT 1 [["id", 492]]
(12.4ms) BEGIN
Image Load (0.4ms) SELECT "images".* FROM "images" WHERE "images"."imagings_id" = $1 AND "images"."imagings_type" = $2 AND "images"."id" IN (1239) [["imagings_id", 492], ["imagings_type", "Review"]]
(0.2ms) COMMIT
Redirected to http://127.0.0.1:3000/reviews/492
Completed 302 Found in 27ms (ActiveRecord: 13.6ms)
You can see here how the images attribute for credit has the change to "Icons galore", but the SQL only fetches the linked image without updating it. Contrast this with the following update to the main model which does a select followed by an update between the BEGIN and COMMIT.
Started PATCH "/reviews/492" for 127.0.0.1 at 2014-07-16 11:26:01 +0100
Processing by ReviewsController#update as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"HvrsCAXXvO4zIqTBw05qSUwU9I2241DXyilhswEbU9o=", "review"=>{"title"=>"Here's a new review", "authors"=>"", "company"=>"", "venue"=>"", "startdate"=>"2014-07-16", "enddate"=>"2014-07-31", "body"=>"<p>Something else</p>", "images_attributes"=>{"0"=>{"title"=>"Doggie", "credits"=>"Icons", "_destroy"=>"0", "id"=>"1239"}, "1"=>{"title"=>"", "credits"=>""}, "2"=>{"title"=>"", "credits"=>""}, "3"=>{"title"=>"", "credits"=>""}}, "user_id"=>"4", "approved"=>"1"}, "commit"=>"Update Review", "id"=>"492"}
User Load (6.4ms) SELECT "users".* FROM "users" WHERE "users"."id" = $1 LIMIT 1 [["id", 1]]
Review Load (0.3ms) SELECT "reviews".* FROM "reviews" WHERE "reviews"."id" = $1 LIMIT 1 [["id", 492]]
(18.1ms) BEGIN
Image Load (0.5ms) SELECT "images".* FROM "images" WHERE "images"."imagings_id" = $1 AND "images"."imagings_type" = $2 AND "images"."id" IN (1239) [["imagings_id", 492], ["imagings_type", "Review"]]
SQL (5.9ms) UPDATE "reviews" SET "body" = $1, "updated_at" = $2 WHERE "reviews"."id" = 492 [["body", "<p>Something else</p>"], ["updated_at", "2014-07-16 10:26:01.455481"]]
(24.8ms) COMMIT
Redirected to http://127.0.0.1:3000/reviews/492
Completed 302 Found in 120ms (ActiveRecord: 56.0ms)
Yet if I try to make the same update in the Rails console, it sometimes works perfectly:
2.1.1 :062 > review = Review.find(492)
Review Load (0.5ms) SELECT "reviews".* FROM "reviews" WHERE "reviews"."id" = $1 LIMIT 1 [["id", 492]]
=> #<Review id: 492, title: "Here's a new review", authors: "", venue: "", startdate: "2014-07-16", enddate: "2014-07-31", body: "<p>Something else</p>", approved: true, created_at: "2014-07-16 09:38:33", updated_at: "2014-07-16 10:26:01", user_id: 4, company: "">
2.1.1 :064 > review.images.first.title = "Doggies galore"
=> "Doggies galore"
2.1.1 :066 > review.save
(0.8ms) BEGIN
SQL (7.5ms) UPDATE "images" SET "title" = $1, "updated_at" = $2 WHERE "images"."id" = 1239 [["title", "Doggies galore"], ["updated_at", "2014-07-16 10:32:39.109784"]]
Review Load (0.3ms) SELECT "reviews".* FROM "reviews" WHERE "reviews"."id" = $1 LIMIT 1 [["id", 492]]
SQL (1.7ms) UPDATE "reviews" SET "updated_at" = '2014-07-16 10:32:39.129314' WHERE "reviews"."id" = 492
(1.6ms) COMMIT
=> true
And sometimes doesn't:
2.1.1 :082 > review = Review.find(492)
Review Load (0.3ms) SELECT "reviews".* FROM "reviews" WHERE "reviews"."id" = $1 LIMIT 1 [["id", 492]]
=> #<Review id: 492, title: "Here's a new review", authors: "", venue: "", startdate: "2014-07-16", enddate: "2014-07-31", body: "<p>Something else</p>", approved: true, created_at: "2014-07-16 09:38:33", updated_at: "2014-07-16 10:38:30", user_id: 4, company: "">
2.1.1 :083 > review.images.first.credits = "Icons galore"
Image Load (0.5ms) SELECT "images".* FROM "images" WHERE "images"."imagings_id" = $1 AND "images"."imagings_type" = $2 ORDER BY "images"."id" ASC LIMIT 1 [["imagings_id", 492], ["imagings_type", "Review"]]
=> "Icons galore"
2.1.1 :084 > review.save!
(0.2ms) BEGIN
(0.3ms) COMMIT
=> true
2.1.1 :085 > review.images.first
Image Load (0.8ms) SELECT "images".* FROM "images" WHERE "images"."imagings_id" = $1 AND "images"."imagings_type" = $2 ORDER BY "images"."id" ASC LIMIT 1 [["imagings_id", 492], ["imagings_type", "Review"]]
=> #<Image id: 1239, title: "Doggies", credits: "Icons", created_at: "2014-07-16 09:38:33", updated_at: "2014-07-16 10:38:30", image_file_name: "ddad7b05-3430-49ed-b129-fd484ac793ad.gif", image_content_type: nil, image_file_size: nil, image_updated_at: nil, imagings_id: 492, imagings_type: "Review", original_filename: "Doggie.gif">
2.1.1 :086 >
I know I'm missing something obvious. Can anyone help please?

Answer 1

I think that you need to make a small change in reviews_params def as follows:
def reviews_params
params.require(:review).permit(:title, :authors, :venue, :startdate, :enddate, :body, :approved, :company, :user_id, images_attributes => [:title, :credits, :image, :_destroy, :id] )
end
Does that work?

Answer 2

i don't think you need the curly braces. Try removing them. Usually nested attributes are listed as a symbol which maps to an array of symbols(attributes). They are separated from attributes of the model in question with just a comma. So something such as,
params.require(:review).permit(:title, :authors, :venue, :startdate, :enddate, :body, :approved, :company, :user_id, :images_attributes => [:title, :credits, :image, :_destroy, :id] ) should work.