Question

I have a function which splits nested attributes into an array so they can be checked for uniqueness and then saves them. The problem is, i’m getting a Can't mass-assign protected attributes: _destroy error because the nested_form gem inserts a hidden_field to highlight which attributes should be deleted.

Here’s the *Posts_Contoller.rb* create function:

def create
   location_set = params[:post].delete(:locations_attributes) unless params[:post][:locations_attributes].blank?

   @post = current_blogger.blog_posts.new(params[:post])

   @post.locations = Location.find_or_initialize_location_set(location_set) unless location_set.nil?


 if @post.save
    redirect_to @post, notice: 'Blog post was successfully created.'
  else
    render action: "new"
  end
end

Here’s the function in location.rb:

def self.find_or_initialize_location_set(location_set)
  #create a locations array
   locations = []
         locations = locations.delete_if { |elem| elem.flatten.empty? }

   location_set.each do |key, location|
       locations << find_or_initialize_by_name(location)
   end

 locations

 end

And here’s the log:

 Started POST "/blog/posts" for 127.0.0.1 at 2012-12-03 17:31:54 +0000
 Processing by Blogit::PostsController#create as HTML Parameters: {"utf8"=>"✓", "authenticity_token"=>"r74iCzC4tJgVI6FiCEH7XzfiTmaqKihF5JSs7Ow3MSI=", "post"=>{"title"=>"This
 is a post about Paris", "body"=>"This is a post about ParisThis is a post about Paris
 This is a post about ParisThis is a post about Paris", "tag_list"=>"", 
 "locations_attributes"=>{"0"=>{"_destroy"=>"false", "name"=>"Paris", "longitude"=>"2.3522219", "latitude"=>"48.856614"}, "1354555760002"=>{"_destroy"=>"false", "name"=>"Los Angeles", "longitude"=>"-118.5155901", "latitude"=>"3
 4.03563310000001"}}}, "_wysihtml5_mode"=>"1", "name"=>"losds", "legname"=>"Los Angeles",    "longitude"=>"-118.5155901", "latitud
 e"=>"34.03563310000001", "commit"=>"Submit"}

 User Load (0.1ms)  SELECT "users".* FROM "users" WHERE "users"."id" = 1 LIMIT 1
 ActsAsTaggableOn::Tag Load (0.1ms)  SELECT "tags".* FROM "tags" INNER JOIN "taggings" ON  "tags"."id" = "taggings"."tag_id" W
 HERE "taggings"."taggable_id" IS NULL AND "taggings"."taggable_type" = 'Blogit::Post' AND  (taggings.context = 'tags' AND taggings.tagger_id IS NULL)

 Location Load (0.1ms)  SELECT "locations".* FROM "locations" WHERE "locations"."name" = 'Paris' LIMIT 1
 LOGGER LOCATIONS ARE[#<Location id: 768, name: "Paris", latitude: #<BigDecimal:7f86aadf6230,'0.48856614E2',18(45)>, longitude:
 #<BigDecimal:7f86aadf5f60,'0.23522219E1',18(45)>, post_id: nil, created_at: "2012-12-01 17:27:33", updated_at: "2012-12-01 17
 :27:33", notes: nil>]
 Location Load (0.2ms)  SELECT "locations".* FROM "locations" WHERE "locations"."name" = 'Los Angeles' LIMIT 1
 Completed 500 Internal Server Error in 97ms

  ActiveModel::MassAssignmentSecurity::Error (Can't mass-assign protected attributes: _destroy):
  app/models/location.rb:23:in `block in find_or_initialize_location_set'
  app/models/location.rb:21:in `each'
  app/models/location.rb:21:in `find_or_initialize_location_set'
  app/controllers/blogit/posts_controller.rb:79:in `create'

Any suggestions for how I can adapt this to include the delete function in the params as before but so I don’t get the Can't mass-assign protected attributes: _destroy error?

Thanks!

Answer 1

You could do something like:

def self.find_or_initialize_location_set(location_set)
  #create a locations array
  locations = []
  locations = locations.delete_if { |elem| elem.flatten.empty? }

  location_set.each do |key, location|
    if location.delete(:_destroy) == "1"
      locations.delete_if {|elem| elem[:name] == location[:name]}
    else
      locations << find_or_initialize_by_name(location)   
    end
  end 

  locations 
end

Calling delete on the associated hash will modify the hash and return the value you’re deleting (or nil if not present).

Or if you need the delete on the initialized location, you could do it there:

def find_or_initialize_by_name_with_delete(location)
  if location.delete(:_destroy)
    do_delete
  end

  find_or_initialize_by_name(location)
end