Rails — use type column without STI?

问题

I want to use a column called type without invoking Single Table Inheritance (STI) - I just want type to be a normal column that holds a String.

How can I do this without having Rails expecting me to have single table inheritance and throwing an exception of The single-table inheritance mechanism failed to locate the subclass...This error is raised because the column \'type\' is reserved for storing the class in case of inheritance.?

Any ideas on how to do this?

回答1:

In Rails 3.1 set_inheritance_column is deprecated, also you can just use nil as a name, like this:

class Pancakes < ActiveRecord::Base
    self.inheritance_column = nil
    #...
end

回答2:

You can override the STI column name using set_inheritance_column:

class Pancakes < ActiveRecord::Base
    set_inheritance_column 'something_you_will_not_use'
    #...
end

So pick some column name that you won't use for anything and feed that to set_inheritance_column.

回答3:

I know this question is rather old and this deviates a bit from the question you are asking, but what I always do whenever I feel the urge to name a column type or something_type is I search for a synonym of type and use that instead:

Here are a couple alternatives: kind, sort, variety, category, set, genre, species, order etc.

回答4:

Rails 4.x

I encountered the problem in a Rails 4 app, but in Rails 4 the set_inheritance_column method does not exist at all so you can't use it.

The solution that worked for me was to disable the single table inheritance by overriding ActiveRecord’s inheritance_column method, like this:

class MyModel < ActiveRecord::Base

  private

  def self.inheritance_column
    nil
  end

end

Hope it helps!

回答5:

If you want to do this for all models, you can stick this in an initializer.

ActiveSupport.on_load(:active_record) do
  class ::ActiveRecord::Base
    # disable STI to allow columns named "type"
    self.inheritance_column = :_type_disabled
  end
end

来源：https://stackoverflow.com/questions/7134559/rails-use-type-column-without-sti