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

Question

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

Here is the create_articles.rb migration file:

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 get the rake aborted error! Msgstr "Uninitialized CreateArticles constant."

Does anyone know why this error continues?

Answer 1

Make sure that your file name and class name say the same thing (except for the class name - with a camel). The contents of your migration file should look something like this: simplify them:

 #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

If you get this error, and it is NOT due to the name of the migration file, there is another possible solution. Open the class directly in the migration as follows:

 class SomeClass < ActiveRecord::Base; end 

Now you can use SomeClass as part of the migration.

Answer 3

It is possible to get a given error if your class names do not correspond to bends (for example, abbreviations) from config/initializers/inflections.rb .

For example, if your flexes include:

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

you may need to make sure the class in your migration:

class CreateDOGHouses < ActiveRecord::Migration[5.0]

but not:

class CreateDOGHouses < ActiveRecord::Migration[5.0]

Not very ordinary, but if you create a migration or model or something else, and then add part of it to the excesses, this can happen. (The example here will result in NameError: uninitialized constant CreateDOGHouses if your class name is CreateDogHouses , at least with Rails 5.)