Rails carrierwave has_many error

rubyonrails-talk
1

Each User has_one Character. Each Character has_one :profilepicture, of class Picturething, which holds a Carrierwave mount_uploader to upload a singe picture. Each Character has_many :standardpictures, also of class Picturething. Picture upload is handled in views/users/edit, which hits the update_pictures method in users_controller.

The idea is to upload one standardpicture at a time. It seems to work, Rails console > Picturething.all shows that a new Picturething has been added to the database, and it is correctly displayed on the page. This is intended to be one of the character.standardpictures.

The weird thing is, somehow in this whole process, the character’s :profilepicture is also set to be the same picture that was uploaded. I don’t understand how this is happening. At no point do I have code saying something like “@character.profilepicture = standardpicture”, but somehow it has decided that both the first :standardpicture and the :profilepicture are one and the same. If the profilepicture exists, which it shouldn’t yet, it is displayed on the edit.html.erb page, where I have the line <% if @character.profilepicture.nil? %>. It displays the uploaded picture here, so clearly profilepicture is not nil, but it should be.

How is this happening?

character.rb:

has_many :standardpictures, class_name: "Picturething", dependent: :destroy
accepts_nested_attributes_for :standardpictures
has_one  :profilepicture, class_name: "Picturething", dependent: :destroy
accepts_nested_attributes_for :profilepicture

``

picturething.rb:

class Picturething < ActiveRecord::Base
  belongs_to      :character
  mount_uploader  :picture, CharacterpicUploader
  validate        :picture_size
end

``

app/views/users/edit.html.erb:

<%= form_for :standardpicture, url: update_pictures_user_path,
             method: :post, html: { multipart: true } do |f| %>
  <%= f.label :picture %>
  <%= f.file_field :picture, accept: 'image/jpeg,image/gif,image/png' %>
  <%= f.submit "Upload pictures", class: "btn btn-primary" %>
<% end %>

``

routes.rb:

post '/users/:callsign/update_pictures', to: 'users#update_pictures',  as: :update_pictures_user

``

users_controller.rb:

def update_pictures
  @character = Character.find_by(callsign: params[:callsign])
  @user = @character.sociable
  @standardpicture = @character.standardpictures.build(update_pictures_user_params)
  if @standardpicture.save
    flash[:success] = "Pictures updated"
    redirect_to(edit_user_path(@user))
  else
    redirect_to(edit_user_path(@user))
  end
end # update_pictures

def update_pictures_user_params
  params.require(:standardpicture).permit(:picture)
end

``

Back to app/views/users/edit.html.erb:

<% if @character.profilepicture.nil? %>
  <p>Select a picture below to use as your profile picture</p>
<% else %>
  <%= image_tag @character.profilepicture.picture %>
<% end %>

``

2

You need two belongs_to here, one for each association. Use unique names, foreign_key and class_name here and in character.rb to specify which is which. Then obviously two _id fields.

Currently it is conflating the two relationships.

Colin

3

Thank you Colin, that fixed it. I appreciate your help.

The solution raises an interesting question, fully specified here on SO if you’re interested:

Rails carrierwave has_many error - Stack Overflow

The question is, is a solution possible with only a single column in the Picturething model? Having two columns seems redundant when they are only ever going to hold the same value (the character_id)?

Thanks again!

4

It is not redundant as which one it is in tells you which association it is. You could have an entry in both. If you can't have an entry in both then you many not have specified the associations in the best way. Have just one association and use a different method of saying which type it is for example.

Colin