How to use ActiveRecord's migration DSL in Rake tasks?

Question

I need to perform some database manipulations, such as creating tables, adding indexes etc. I would like to use the same methods used in migrations, such as create_table, add_index etc. However, when I try this I get

NoMethodError: undefined method `add_index' for main:Object

I added this at the beginning of my file:

include ActiveRecord::ConnectionAdapters::SchemaStatements

However, now I get the following error:

NameError: undefined local variable or method `allowed_index_name_length' for main:Object

This is defined in ActiveRecord::ConnectionAdapters::DatabaseLimits. I tried to include ActiveRecord::ConnectionAdapters, but it didn't include all subclasses/modules, as I expected.

So the question is - what should I do in order to be able to write the same code I am normally able to write within a migration?

Answer 1

The methods in a migration are all class methods of the ActiveRecord::Migration class. So you can call them like

ActiveRecord::Migration.add_index :foo, :bar