Ruby-on-rails 当我运行 rake:db migrate 命令时，出现错误“未初始化的常量 CreateArticles”
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When I run the rake:db migrate command I get an error "Uninitialized constant CreateArticles"
提问by featureBlend
I created a model ruby script/generate model Article (simple enuff)
我创建了一个模型 ruby 脚本/生成模型文章（简单的enuff）
Here is the migration file create_articles.rb:
这是迁移文件 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."
当我运行 rake:db migrate 命令时，我收到一个错误 rake aborted！“未初始化的常量 CreateArticles。”
Does anyone know why this error keeps happening?
有谁知道为什么这个错误不断发生？
回答by thetacom
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:
确保你的文件名和类名是一样的（除了类名是驼峰式的）。你的迁移文件的内容应该是这样的，也简化了一点：
#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
回答by 123
If you're getting this error and it's NOT because of the migration file name, there is another possible solution. Open the class directly in the migration like this:
如果您收到此错误并且不是因为迁移文件名，还有另一种可能的解决方案。在迁移中直接打开类，如下所示：
class SomeClass < ActiveRecord::Base; end
It should now be possible to use SomeClasswithin the migration.
现在应该可以SomeClass在迁移中使用了。
回答by dgsan
It's possible to get the given error if your class names don't match inflections (like acronyms) from config/initializers/inflections.rb.
如果您的类名与config/initializers/inflections.rb.
For example, if your inflections include:
例如，如果您的语调包括：
ActiveSupport::Inflector.inflections(:en) do |inflect|
inflect.acronym 'DOG'
end
then you might need to make sure the class in your migration is:
那么您可能需要确保迁移中的类是：
class CreateDOGHouses < ActiveRecord::Migration[5.0]
class CreateDOGHouses < ActiveRecord::Migration[5.0]
rather than:
而不是：
class CreateDogHouses < ActiveRecord::Migration[5.0]
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 CreateDOGHousesif your class name is CreateDogHouses, at least with Rails 5.)
不是很常见，但是如果您生成迁移或模型或其他东西，然后将其中的一部分添加到变形中，则可能会发生。（这里的示例将导致NameError: uninitialized constant CreateDOGHouses如果您的类名是CreateDogHouses，至少在 Rails 5 中是这样。）
