Paperclip Nested attributes on polymorphic model not getting saved (RAILS) - ruby-on-rails

Question

I can not for the life of me figure out why certain attributes of my paperclip attachment aren't not getting saved to the database via nested attributes. My post has one attachment but the :media params for the :attachment attribute not being saved, but the attachment object is being created. I figure I have something messed up with the way my strong params are being passed in. Thanks in advance.
NIL Params
media_file_name: nil, media_content_type: nil, media_file_size: nil, media_updated_at: nil>
IRB:
irb(main):001:0> p = Post.last
Post Load (0.1ms) SELECT "posts".* FROM "posts" ORDER BY "posts"."id" DESC LIMIT 1
=> #<Post id: 40, body: "test info", expiration: 1467065130586, created_at: "2016-06-27 21:05:41", updated_at: "2016-06-27 21:05:41">
irb(main):002:0> p.attachment
Attachment Load (0.2ms) SELECT "attachments".* FROM "attachments" WHERE "attachments"."attachable_id" = ? AND "attachments"."attachable_type" = ? LIMIT 1 [["attachable_id", 40], ["attachable_type", "Post"]]
=> #<Attachment id: 26, attachable_id: 40, attachable_type: "Post", created_at: "2016-06-27 21:05:41", updated_at: "2016-06-27 21:05:41", media_file_name: nil, media_content_type: nil, media_file_size: nil, media_updated_at: nil>
irb(main):003:0>
Schema:
ActiveRecord::Schema.define(version: 20160627165514) do
create_table "attachments", force: :cascade do |t|
t.integer "attachable_id"
t.string "attachable_type"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
t.string "media_file_name"
t.string "media_content_type"
t.integer "media_file_size"
t.datetime "media_updated_at"
end
add_index "attachments", ["attachable_type", "attachable_id"], name: "index_attachments_on_attachable_type_and_attachable_id"
create_table "posts", force: :cascade do |t|
t.text "body"
t.integer "expiration", limit: 8
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
end
Post Model:
class Post < ActiveRecord::Base
has_one :attachment, as: :attachable, dependent: :destroy
accepts_nested_attributes_for :attachment
end
Post Controller:
class PostsController < ApplicationController
def show
#I don't need this.
end
def index
#posts = Post.all
end
def new
#post = Post.new
#post.build_attachment
end
def create
#post = Post.new(post_params)
#post.build_attachment
if #post.save
respond_to do |format|
format.html {redirect_to(posts_path, notice:"Post succesfully created")}
format.js
end
else
render :new
end
end
private
def post_params
params.require(:post).permit(:body,:expiration, attachment_attributes: [:media])
end
end
Attachment Model:
class Attachment < ActiveRecord::Base
belongs_to :attachable, polymorphic:true
has_attached_file :media
end
HTML FORM:
<%=form_for(#post, url: posts_path, html:{multipart:true}) do |form|%>
<%=form.text_area :body%>
<%=fields_for(:attachment) do |ff|%>
<%= ff.file_field :media %>
<%end%>
<%=form.hidden_field :expiration%>
<%=form.submit "Post", class: "post-submit-button"%>
<%end%>
Log Dumb:
Started POST "/posts" for ::1 at 2016-06-27 16:05:41 -0500
Processing by PostsController#create as HTML
Parameters: {"utf8"=>"✓", "authenticity_token"=>"/b54OJOBJIaR551MAHDujCxjciI7OAx93EQAVrugCz0xtYnafaSH4widYOftZJUbDHLfmI6jly5eG5AxCCNJbQ==", "post"=>{"body"=>"test info", "expiration"=>"1467065130586"}, "attachment"=>{"media"=>"IMG_1004.jpg"}, "commit"=>"Post"}
(0.1ms) begin transaction
SQL (0.3ms) INSERT INTO "posts" ("body", "expiration", "created_at", "updated_at") VALUES (?, ?, ?, ?) [["body", "test info"], ["expiration", 1467065130586], ["created_at", "2016-06-27 21:05:41.321484"], ["updated_at", "2016-06-27 21:05:41.321484"]]
SQL (0.1ms) INSERT INTO "attachments" ("attachable_type", "attachable_id", "created_at", "updated_at") VALUES (?, ?, ?, ?) [["attachable_type", "Post"], ["attachable_id", 40], ["created_at", "2016-06-27 21:05:41.323335"], ["updated_at", "2016-06-27 21:05:41.323335"]]
(1.4ms) commit transaction
Redirected to http://localhost:3000/posts
Completed 302 Found in 8ms (ActiveRecord: 1.9ms)
Started GET "/posts" for ::1 at 2016-06-27 16:05:41 -0500
Processing by PostsController#index as HTML
Rendered layouts/_user_menu.html.erb (0.1ms)
Rendered posts/index.html.erb within layouts/application (1.8ms)
Completed 200 OK in 26ms (Views: 25.8ms | ActiveRecord: 0.0ms)

Answer 1

You're not binding your fields_for to your form. Try this:
<%=form_for(#post, url: posts_path, html:{multipart:true}) do |form|%>
<%=form.text_area :body%>
<%= form.fields_for(:attachment) do |ff|%>
<%= ff.file_field :media %>
<% end %>
<%=form.hidden_field :expiration%>
<%=form.submit "Post", class: "post-submit-button"%>
<%end%>