[ruby-on-rails] Ruby on Rails generates model field:type - what are the options for field:type?

2 Answers

To create a model that references another, use the Ruby on Rails model generator:

$ rails g model wheel car:references

That produces app/models/wheel.rb:

class Wheel < ActiveRecord::Base
  belongs_to :car

And adds the following migration:

class CreateWheels < ActiveRecord::Migration
  def self.up
    create_table :wheels do |t|
      t.references :car


  def self.down
    drop_table :wheels

When you run the migration, the following will end up in your db/schema.rb:

$ rake db:migrate

create_table "wheels", :force => true do |t|
  t.integer  "car_id"
  t.datetime "created_at"
  t.datetime "updated_at"

As for documentation, a starting point for rails generators is Ruby on Rails: A Guide to The Rails Command Line which points you to API Documentation for more about available field types.


I'm trying to generate a new model and forget the syntax for referencing another model's ID. I'd look it up myself, but I haven't figured out, among all my Ruby on Rails documentation links, how to find the definitive source.

$ rails g model Item name:string description:text (and here either reference:product or references:product). But the better question is where or how can I look for this kind of silliness easily in the future?

Note: I've learned the hard way that if I mistype one of these options and run my migration then Ruby on Rails will totally screw up my database... and rake db:rollback is powerless against such screwups. I'm sure I'm just not understanding something, but until I do... the "detailed" information returned by rails g model still leaves me scratching...

I had the same issue, but my code was a little bit different.

def new @project = Project.new end

And my form looked like this:

<%= form_for @project do |f| %> and so on.... <% end %>

That was totally correct, so I didn't know how to figure it out.

Finally, just adding url: { projects: :create } after <%= form-for @project worked for me.

Remember to not capitalize your text when writing this command. For example:

Do write:

rails g model product title:string description:text image_url:string price:decimal

Do not write:

rails g Model product title:string description:text image_url:string price:decimal

At least it was a problem to me.