Changing a script into a database migration

Hi,

 I have a little dilemma where and how to place a script in my

rails application. I work on a reimplementation and the original
database structure is changed. The old data needs to be migrated into
a new schema. The migration is executed very few times, maybe just
once. As the data set might be huge, I also do not wish to execute it
often.
Currently I placed the script in dir /script, but I think it does
not fit the place well, it is meant for other things… isn’t it? I
think it should among the migrations, but I don’t want it to be
executed always as the others migration when the data model is
created.
Could you give me advice, how to tackle elegantly this thing? I
want to keep my code in the rails project structure, although it will
be executed few times, maybe only now. And I’d like to have it at a
place which it fits well. Thanks for help!

Georg

Fifigyuri wrote:

Hi,

 I have a little dilemma where and how to place a script in my

rails application. I work on a reimplementation and the original
database structure is changed. The old data needs to be migrated into
a new schema. The migration is executed very few times, maybe just
once. As the data set might be huge, I also do not wish to execute it
often.
Currently I placed the script in dir /script, but I think it does
not fit the place well, it is meant for other things… isn’t it? I
think it should among the migrations, but I don’t want it to be
executed always as the others migration when the data model is
created.

The preferred way to create the DB is to use rake db:schema:load.
Migrations are only for migration. So just write the script as a
migration. That’s what migrations are for.

 Could you give me advice, how to tackle elegantly this thing? I

want to keep my code in the rails project structure, although it will
be executed few times, maybe only now. And I’d like to have it at a
place which it fits well. Thanks for help!

You are describing a classic use case for a migration. There’s no
reason to do it any other way. If you’re worried about it being run
when it shouldn’t be, just throw in some if statements.

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

Georg

I correct myself. The problem was in my code, and thought that not
accessing the ActiveRecord::Base from Migrations is intended. No, it
is possible, sorry for the false alarm.

Thanks, I followed your advice. And its almost fine. The original
script operated with the models, putting it to a migration causes take
the migration misses the model. Claims “uninitialized constant” for
the model name. I tried to require the model directly. On the other
hand I am not sure whether using models in migrations is intended…
currently it seems to be the most convenient way of changing the data.

bw

On Sep 5, 3:56 pm, Marnen Laibow-Koser <rails-mailing-l…@andreas-

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