I am starting a new rails project and have been given a DB with data etc. The good news is that the data is not being used by any other system so even though the DB has been designed and given to me I have liberty to change as needed. My goal would be to tweak the DB before starting to work well follow rails conventions. I will change table names and add the created_at, modified_at fields manually. My issue comes in with the ID field/primary key. I would love to add the ID field as primary key and auto_increment so that I can create my Rails app fresh and everything works as if I created through a migration. Trouble being that each table already has a primary key, usually <tablename_id> and that field also exists in other tables. So I cant just change the field name to ID. But since the DB isn't being used by any other system, can I just create a new column named ID and make it the primary key(auto_increment) and remove the primary key status from the existing? In this scenario all the data given to me remains intact I just create and change the primary key. Or would this destroy the data relationships of these table and cause more issues down the road?
Why not start from scratch with a rails-created database, then import the old data into it?
Seems like it'd be the least pain solution.
Larry
that is a great idea and I had that thought. It has several tables and some of the table many fields so is there an easy way to do that? Do you think taking a SQL dump of the DB and then copy paste most it into the migration file and then run rake db:migrate?? any other suggestions? I would think this is a very common thing amongst rails developers being that often you are given the data or some of it, regardless of if the DB is already relied upon or not - wanted to make sure I was doing things smartly
agilehack wrote:
that is a great idea and I had that thought. It has several tables and some of the table many fields so is there an easy way to do that? Do you think taking a SQL dump of the DB and then copy paste most it into the migration file and then run rake db:migrate??
No way! That will just keep the old schema. (But see below.)
any other suggestions? I would think this is a very common thing amongst rails developers being that often you are given the data or some of it, regardless of if the DB is already relied upon or not - wanted to make sure I was doing things smartly
The smart thing to do: * Look at the old DB. * Understand the data in it. * Figure out a way of modeling that data that Rails will like. * Write migrations to create a new DB from scratch. (It might look nothing like the old one.) * Import data as appropriate.
Alternatively, start by duplicating the legacy schem as you suggested, then refactor it bit by bit.
Best,
