I have some major structure change issues with an ruby on rails application, and I’d like to ask you about how i can handle that. I will make some dummy problems for you to show what i want to reach:
Having a Client model with first_name and last_name should now come together as name:
For the model it would be easy to have just
def name
first_name + ’ ’ + last_name
end
That works, but now I want to change the database this way, so we dont need the first_name and last_name anymore:
I could create a migration having a name:string:index field.
but after that - how can I make all the first_name and last_name applied there, and remove the first_name and last_name fields?
same for appointments:
We had a start_datetime and an end_datetime which until now was enaugh. but now we want to change it to
planned_start_time end actual_start_time (same for end time)
on the migration all the old data from start_datetime should be put into both (for historical data) planned end actual times. For the future this will differ.
How can I make this migrations?
If I know about that later there will be some table changes, but maybe I understand the routines for that.
Is there also any sql way doing it with rails? For sql itself it would be easy with INSERT…SELECT, so maybe I could generate migrations with sql code?
I have some major structure change issues with an ruby on rails
application, and I'd like to ask you about how i can handle that. I
will
make some dummy problems for you to show what i want to reach:
1. Having a Client model with first_name and last_name should now come
together as name:
For the model it would be easy to have just
def name
first_name + ' ' + last_name
end
That works, but now I want to change the database this way, so we dont
need
the first_name and last_name anymore:
IMHO that is a bad idea. Chances are likely that you would come to
regret that decision. If you ever use either first_name or last_name
separately from each other then you violate First Normal Form (1NF). The
bigger issue is that once you decide to concatenate these two values in
to a single field there's no going back. There is no reliable algorithm
that can separate the two distinct values.
I say if you already have separate first and last names keep it that way
and add full_name method to the model. That costs you nothing really and
preserves flexibility in your app.
I could create a migration having a name:string:index field.
but after that - how can I make all the first_name and last_name applied
there, and remove the first_name and last_name fields?
Whatever you decide, you are not limited to the ActiveRecord helpers in
your migrations. You can run any arbitrary SQL you want using the
execute method: