On Saturday, January 20, 2018 at 3:54:27 AM UTC, kenatsun wrote:
> Using scaffold, I generated two models, Person and Offer, and the forms to
> manage them. Offer has a belong_to association with Person. After running
> the generator, all the forms immediately worked fine.
>
> But then I discovered an external requirement that the foreign key column in
> the offers table, which was named person_id per Rails conventions, needed to
> be renamed as worker_id. Since then, the Offer forms don't work. They evoke
> a variety of errors, all related to the renamed column. It seems that the
> system no longer recognizes it as implementing the Offer to Person
> association.
>
You need to tell the has_many/belongs_to associations to use the new key, ie
(In Offer)
belongs_to :person, foreign_key: “worker_id”
And similarly for the has_many in the Person class. The form helpers need to
be using the worker_id , since person_id doesn’t exist anymore.
Fred
> I figure I need to make some declaration somewhere to restore this
> associative functionality, but I can't figure out how to do this. Can you
> help?
>
> Here are some details:
>
> The generate commands I used were:
>
>
> rails generate scaffold Person name:string
> rails generate scaffold Offer terms:string person:belongs_to
> rake db:migrate
>
> I tweaked the Offer forms a bit to show People's names in display pages and
> provide a drop-down on edit forms. The tweaked Offer index.html.erb looked
> like this:
>
>
>
> ...
> <% @offers.each do |offer| %>
> <tr>
> <td><%= offer.terms %></td>
> <td><%= offer.person.name %></td>
> <td><%= link_to 'Show', offer %></td>
> <td><%= link_to 'Edit', edit_offer_path(offer) %></td>
> <td><%= link_to 'Destroy', offer, method: :delete, data: { confirm:
> 'Are you sure?' } %></td>
> </tr>
> <% end %>
> ...and the tweaked Offer _form.html.erb looked like this:
>
>
> <%= form_with(model: offer, local: true) do |form| %>
> ...
> <div class="field">
> <%= form.label :terms %>
> <%= form.text_field :terms, id: :offer_terms %>
> </div>
>
> <div class="field">
> <%= form.label :person_id %>
> <%= form.collection_select :person_id, Person.order(:name), :id, :name %>
> </div>
> ...
>
> At this point, everything worked fine.
>
> Then I wrote and executed this migration:
>
>
> class RenameOfferPersonId < ActiveRecord::Migration[5.1]
> def change
> rename_column :offers :person_id :worker_id
> end
> end
> Since then, all of my Offer forms get errors, always related to the renamed
> foreign key column. Here's the error for index.html.erb:
>
>
>
>
> Showing /home/ec2-user/environment/ww1/app/views/offers/index.html.erb
> where line #18 raised:
>
> undefined method `name' for nil:NilClass
> ...
> <td><%= offer.person.name %></td>
>
> If I change the offending line to:
>
>
> <td><%= offer.worker_id %></td>
> the page displays, but only the value of worker_id is displayed, not the name
> of the referenced Person.
>
> The Offer edit form displays, including its dropdown box containing Person
> names. But when I try to save an update, I get:
>
>
> ActiveModel::UnknownAttributeError in OffersController#update
> unknown attribute 'person_id' for Offer.
>
>
> Extracted source (around line #44):
>
> ...
>
>
>
>
> 44 if @offer.update(offer_params)
>
> If I change these lines in _form.html.erb
>
>
> <%= form.label :person_id %>
> <%= form.collection_select :person_id, Person.order(:name), :id, :name %>
> to
>
>
> <%= form.label :worker_id %>
> <%= form.collection_select :worker_id, Person.order(:name), :id, :name %>
> the form still displays OK, but when I try to save an update, I get a
> different error:
>
>
>
> 1 error prohibited this offer from being saved:Person must exist
>
> ~ Thanks in advance for your help
> ~ Ken
--
You received this message because you are subscribed to the Google Groups "Ruby
on Rails: Talk" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/rubyonrails-talk/861f71bc-0dde-4a36-95d8-75e2bce3bea3%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
