Rails%203%20In%20Action

Attaching many files
Directly before the fields_for call, you set a local variable called number, which is
incremented whenever you render a label B.
You use fields_for much in the same way you use form_for. You call fields_for
on the f block variable from form_for, which tells it you want to define nested fields
inside this original form. The argument to fields_for—:assets C—tells Rails the
name of the nested fields.
The file field inside this fields_for now has the name attribute of
ticket[assets][asset] rather than simply ticket[asset], meaning it will be available
in the controller as params[:ticket][:assets][:asset].
When you run this scenario with bin/cucumber features creating_tickets
.feature:36, it now fails because it still can’t find the second file-upload field:
And I attach the file "spec/fixtures/spin.txt" to "File #2"
cannot attach file, no file field with id, name,
or label 'File #2' found (Capybara::ElementNotFound)
To make this appear, you must define an assets association in your Ticket model so
the fields_for in your view will provide file_fields for three new Asset objects. If
this method is available and you’ve declared that your model accepts nested attributes
for this association, fields_for iterates through the output from this method and
renders the fields from fields_for for each element.
You can define this assets method by defining a has_many association in your
Ticket model:
has_many :assets
Underneath this has_many, you also define that a Ticket model accepts nested attributes
for assets by using accepts_nested_attributes_for:
accepts_nested_attributes_for :assets
This little helper tells your model to accept asset attributes along with ticket attributes
whenever you call methods like new, build, and update. It has the added bonus of
switching how fields_for performs in your form, making it reference the association
and calling the attributes it defines assets_attributes rather than assets.
When you run the scenario with bin/cucumber features/creating_tickets
.feature:38, you see again that the Asset is not defined:
And I follow "New Ticket"
uninitialized constant Ticket::Asset (ActionView::Template::Error)
You’d best get onto that then!
C The assets
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