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.
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
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