Setting default value for fields in Rails

Question

So I have this model Request, that was working perfectly. I decided to add it a "status" field, with a default value

def change
    create_table :requests do |t|

        t.references :owner,     index: true
        t.references :pretender, index: true
        t.belongs_to :book,      index: true

        t.string :status, value: "pending", null: false

        t.timestamps null: false
    end
end

But now I get an COnSTRAINT NOT NULL on this line:

...
user.requests.build owner_id: oid, pretender_id: pid, book_id: bid
...

Which was working just fine. If the field has a default value, I shouldn't need to define it on the buildmethod, no?

MurifoX · Accepted Answer · 2015-07-23 12:37:14Z

3

In the migration file, the syntax is not value, it is default:

t.string :status, null: false, default: 'pending',

answered Jul 23, 2015 at 12:37

MurifoX

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1 Comment

Enrique Moreno Tent Over a year ago

Wow, that is embarassing... Thanks!

max · Accepted Answer · 2015-07-23 12:58:24Z

1

As MurifoX already has answered use the default option instead of value.

ActiveRecord has a really nice trick up its sleeve called enumerables. Basically you store the status as an integer:

t.integer :status, null: false, default: 0, index: true

And then in your model you add the values that the column maps to:

class Request < ActiveRecord::Base
  enum status: [:pending, :reserved, :foo, :bar]
end

This automatically gives you:

Request.reserved # scopes
request.pending? # interrogation methods
request.reserved! # bang methods to change the status.

Its also much faster to perform queries on the database based on the status since you are comparing integers instead of strings.

answered Jul 23, 2015 at 12:58

max

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3 Comments

Enrique Moreno Tent Over a year ago

Now this is BADASS! I get the interrogation method and the bang method, but what does the first one do?

Enrique Moreno Tent Over a year ago

Oh, I see. You use the class name, not the instance! Cool! :D

max Over a year ago

The first one does Request.where(status: :reserved)

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