def pre_migrate_database
old_schema_version = get_schema_version
new_schema_version = File.read(File.join(source_directory,'db','schema_version')).to_i
return unless old_schema_version > 0
if old_schema_version > new_schema_version
message "Downgrading schema from #{old_schema_version} to #{new_schema_version}"
in_directory install_directory do
unless system("rake -s migrate VERSION=#{new_schema_version}")
raise InstallFailed, "Downgrade migrating from #{old_schema_version} to #{new_schema_version} failed."
end
end
end
end