Rails%203%20In%20Action

First steps
class CreateProjects < ActiveRecord::Migration
def up
remove_column :projects, :name
end
def down
add_column :projects, :name, :string
end
end
This is because ActiveRecord won’t know what type of field to re-add this column as,
so you must tell it what to do in the case of this migration being rolled back.
The first line tells Active Record you want to create a table called projects. You
call this method in the block format, which returns an object that defines the table. To
add fields to this table, you call methods on the block’s object (called t in this example
and in all model migrations), the name of which usually reflects the type of column
it is, and the first argument is the name of that field. The timestamps method is
special: it creates two fields, the created_at and updated_at datetime fields, which
are by default set to the current time in coordinated universal time (UTC) by Rails
when a record is created and updated, respectively.
A migration doesn’t automatically run when you create it—you must run it yourself
using rake db:migrate. This command migrates the database up to the latest migration,
which for now is the only migration. If you create a whole slew of migrations at
once, this command migrates them in the order they were created.
With this model created and its related migration run, you can now run the feature
and have the second step passing once again and the third one failing:
When I follow "New Project"
And I fill in "Name" with "TextMate 2"
cannot fill in, no text field, text area or password field with
id, name, or label 'Name' found (Capybara::ElementNotFound)
Now you are back to the missing field error. To add this field to the new action’s view,
you use a partial. Partials allow you to render dynamic content chunks in your views
and are helpful for reducing duplicate code. You put this form in a partial because
you must use it later in the edit action of your controller. To create a partial for your
projects, create a new file called app/views/projects/_form.html.erb; the underscore
prefix to this file’s name indicates that it’s a partial. You fill this file with the content
from the following listing.
Listing 3.15 app/views/projects/_form.html.erb
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