Rails engine, invoking container app's native migration generator
Others on SO have asked (and been answered) about how to write a migration template which will be copied to the container app just like any other template. We're writing a Rails engine which needs to work in multiple major versions of Rails, so we're hoping to find a way to use the app's native migration generator to generate migrations, rather than either having to maintain multiple templates, or needing to write a complex template which can handle multiple major versions.
I have seen in the Rails engine documentation (9.12) that you can invoke other generators like so:
generate "scaffold", "forums title:string description:text"
where the name of the generator, and its arguments, are single strings. However, the following doesn't work for us:
generate 'migration', 'create_table_name column1:type ...'
For us, regardless of Rails version, a migration file is created with the proper name, but empty up and down (or change ) methods. So it's as if only the first argument is actually being received by the native migration generator.
Is there in fact a way to do this?
This worked fine for me by using the camel case generate syntax:
lib/generators/test_generator.rb
class TestGenerator < Rails::Generators::Base
def build_table
generate 'migration', 'CreateFoo name:string'
end
end
rails g test created the migration:
db/migrate/20170128040004_create_foo.rb
class CreateFoo < ActiveRecord::Migration[5.0]
def change
create_table :foos do |t|
t.string :name
end
end
end
So I think you just need to use the syntax CreateTableName and not create_table_name .