Rails form builder with admin namespace

Question

The code below works well to create new transactions on the Invoice show view. It however doesn't work when in admin namespace. ie /admin/invoices/1/ but works on /invoices/1/

show.html.erb

<%= form_for([@invoice, @invoice.transactions.build]) do |form| %>
....
transactions form input

routes.rb

resources :invoices do
  resources :transactions
end

Answer 1

When calling form_for in a namespace route like /admin/invoices/1/ , Rails will automatically append admin to your route. In other words, form_for([@invoice, @invoice.transactions.build]) would POST to a route like /admin/invoice/:id/transactions/ rather than /invoice/:id/transactions/ .

To fix, explicitly set the URL of the form and use a route helper method to infer the correct route:

form_for(@invoice, url: invoice_transaction_url(@invoice.id))

Note that you may need to replace invoice_transaction_url with the correct route. Use rake routes to find the helper method that corresponds to the desired controller POST action.