Here is example of migration from my RoR application. It is intranet
application that is deployed in many locations (many clients) so
needs to be repeated at every server.
class WatchdogTimerField < ActiveRecord::Migration
def self.up
#add columns to various tables
add_column :alarm_descriptors, :watchdog_timer, :integer, :default
=> 0, :null => false
add_column :alarm_descriptors, :watchdog_timer_unit, :integer, :default
=> 1, :null => false
add_column :rtu_descriptors, :watchdog_time, :integer, :default =>
0, :null => false
#update data in added column:
RtuDescriptor.reset_column_information
for rtu in RtuDescriptor.find(:all)
rtu.update_attribute('watchdog_time', Time.now().to_i)
end
end
def self.down
remove_column :alarm_descriptors, :watchdog_timer
remove_column :alarm_descriptors, :watchdog_timer_unit
remove_column :rtu_descriptors, :watchdog_time
end
end
#######################
another example, more complicated - includes logic to update data in
existing database, fixing possible errors:
class AddRelationsToClient < ActiveRecord::Migration
def self.up
klient = Client.find(:first)
klient ||= Client.create( :name => 'blah blah',
:activation_date => Time.now(),
:unit_cost => 0.0,
:html_title => '<img src=/images/
logo.gif width=134 height=132 border=0><p>Welcome to ...!</p>',
:sms_limit => 0)
add_column :rtu_groups, :client_id, :integer, :default => 0, :null
=> false
add_column :user_groups, :client_id, :integer, :default =>
0, :null => false
remove_column :users, :link
remove_column :user_groups, :credit
RtuGroup.update_all :client_id => klient.id
UserGroup.update_all :client_id => klient.id
end
def self.down
remove_column :rtu_groups, :client_id
remove_column :user_groups, :client_id
end
end
On Jul 8, 9:25 am, mdipierro <mdipie...@cs.depaul.edu> wrote:
> 1. I agree that RoR migrations are more powerful but web2py can update
> the data too. Can you provide an example of something you can do in
> RoR migrations that you believe cannot be done in web2py?
>
> 2. That is a major philosophical difference. Most people including me
> believe that a proper mapping between database tables and object in a
> programming language is not possible. Any attempt to do it necessarily
> imposes limitations on what you do or forces you to introduce an
> unnatural syntax. That is way they have an ORM and we have a DAL. In
> practice this is syntactical difference more than a functional one.
> They say
>
> record.is_logged()
>
> we say
>
> is_logged(record)
>
> The rails syntax can easily be implemented on top of web2py and I do
> not completely exclude it will be supported in the new DAL (without
> going to a full ORM).
>
> Massimo
>
> On Jul 8, 12:03 am, SergeyPo <ser...@zarealye.com> wrote:
>
>
>
> > I like web2py and prefer it over RoR but two things I am missing:
> > 1. migrations (RoR migrations are really more powerful, you write the
> > script that not only changes database scheme but also can update data,
> > you have full control etc.)
> > 2. models (web2py model layer is purely database layer which you use
> > by ORM, in RoR models are classes that run on top of ORM and let you
> > program custom methods; e.g. for class 'Users' you can develop methods
> > 'is_logged', 'is_admin', 'dont_destroy_admin' etc etc.)
>
> > Many-to-many relations that are supported by many frameworks are
> > actually a drawback and Rails have already changed original concept to
> > 'belongs ... through' which is actually a manual table definition for
> > many-to-many relations; so in web2py you just define a table with all
> > necessary fields for your particular situation.
>
> > And the biggest advantage of web2py is Python language. It's by far
> > more mature than Ruby and have so many libraries available that you
> > hardly have to develop any system level task, you just script the
> > behavior you need in terms of domain area of your application. I mean,
> > if you want to use statistics you use scipy, you need pdf - reportlab,
> > networking - no problem, AI - no problem. Web2py makes it easy to
> > install libraries and distribute/deploy with your apps.
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