checking table existence in Rails' migrations
I just refactored a table and in the migration I created for it I first need to drop the table and then create it from scratch, so the first line of self.up is drop_table :table_name. But when I go back and forth over that migration, the second time around the table doesn't exist (because it got dropped proper in self.down), so I need to check that the table exists before I try to drop it in self.up.
Here's the function I created to do that check:
def self.table_exists?(name)
ActiveRecord::Base.connection.tables.include?(name)
end
And here's the new first line of self.up:
drop_table :table_name if self.table_exists?("table_name")
Clean.
4 Comments
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Couldn't you use AR's table_exists? method?
Here's something quick to check for a column:
Model.columns_hash.has_key("column_name")?Actually, it should be
Model.columns_hash.has_key?("column_name")You could also use Rails' built-in force parameter:
create_table :some_table, :force => true do |t|
t.integer user_id, :null => false
end
This forces a new table to be created even if a current table with that name exists.