When I run the rake:db migrate command I get an error "Uninitialized constant CreateArticles"

Question

I created a model ruby script/generate model Article (simple enuff)

Here is the migration file create_articles.rb:

def self.up   create_table :articles do |t|     t.column :user_id, :integer     t.column :title, :string     t.column :synopsis, :text, :limit => 1000     t.column :body, :text, :limit => 20000     t.column :published, :boolean, :default => false     t.column :created_at, :datetime     t.column :updated_at, :datetime     t.column :published_at, :datetime     t.column :category_id, :integer   end  def self.down   drop_table :articles  end end 

When I run the rake:db migrate command I receive an error rake aborted! "Uninitialized constant CreateArticles."

Does anyone know why this error keeps happening?

Answer 1

Be sure that your file name and class name say the same thing(except the class name is camel cased).The contents of your migration file should look something like this, simplified them a bit too:

#20090106022023_create_articles.rb class CreateArticles < ActiveRecord::Migration      def self.up     create_table :articles do |t|       t.belongs_to :user, :category       t.string :title       t.text :synopsis, :limit => 1000       t.text :body, :limit => 20000       t.boolean :published, :default => false       t.datetime :published_at       t.timestamps     end   end    def self.down     drop_table :articles   end end 

Answer 2

It's possible to get the given error if your class names don't match inflections (like acronyms) from config/initializers/inflections.rb.

For example, if your inflections include:

ActiveSupport::Inflector.inflections(:en) do |inflect|   inflect.acronym 'DOG' end 

then you might need to make sure the class in your migration is:

class CreateDOGHouses < ActiveRecord::Migration[5.0]

rather than:

class CreateDogHouses < ActiveRecord::Migration[5.0]

Not super common, but if you generate a migration or a model or something, and then add part of it to inflections afterwards it may happen. (The example here will cause NameError: uninitialized constant CreateDOGHouses if your class name is CreateDogHouses, at least with Rails 5.)