Adding scopes breaks migrations (Rails 3 beta 4)
Paul Campbell
in my user.rb I have a scope:
scope :public, where(:private => false)
This was absolutely fine when I added the scope, since the "private"
field was in the database.
I wanted to modify the migration, so I rolled back the database, but
by doing so, I nuked the private field.
Now when I try to rollback or run any migrations, I get:
No attribute named `private` exists for table `users`
Full Trace:
http://gist.github.com/461216
This is happening (I think) because Rails is building the predicate
for the scope at runtime ... when the field doesn't exist.
Whenever something like this happened in Rails 2, I'd normally put the
class inside the migration, eg:
class AddUsernameToUser < ActiveRecord::Migration
class User < ActiveRecord::Base
end
def self.up
add_column :users, :username, :string
add_column :users, :private, :boolean, :default => false
end
def self.down
remove_column :users, :private
remove_column :users, :username
end
end
This doesn't work in this case, because it all happens before _any_
migration is run.
So basically, I have to remove the scope to run any migrations.
This is fine for now, as I can move on with development, but the
implication is that if I start off with a clean database, and run rake
db:migrate, it won't work.
Now, I know that best practice is to use rake db:schema:load, but I
think that this is still a brittle case.
Basically, by adding a scope that depends on a field existing, all
prior migrations break.
—Paul
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Paul Campbell
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Ernie Miller
insights along those lines.
http://www.railway.at/2010/03/09/named-scopes-are-dead/
In the Rails 3 app I've been working on, my scopes are just class
methods like shown there.
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Pratik
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Paul Campbell
> I swear I had fixed this. Will have another look.
It may be fixed in edge, I'm working off beta4. Will switch to edge
and double check.
—P
Ernie Miller
/Users/paul/.rvm/gems/ree-1.8.7-2010.02@roadio/gems/devise-1.1.rc2/lib/devise/mapping.rb:88:in `to'/Users/paul/.rvm/gems/ree-1.8.7-2010.02@roadio/gems/devise-1.1.rc2/lib/devise/rails/routes.rb:95:in `devise_for'/Users/paul/.rvm/gems/ree-1.8.7-2010.02@roadio/gems/devise-1.1.rc2/lib/devise/rails/routes.rb:91:in `each'/Users/paul/.rvm/gems/ree-1.8.7-2010.02@roadio/gems/devise-1.1.rc2/lib/devise/rails/routes.rb:91:in `devise_for'/Users/paul/Dropbox/Sites/roadio/roadio/config/routes.rb:6
Rob Biedenharn
On Jul 2, 2010, at 8:40 AM, Paul Campbell wrote:
> On Fri, Jul 2, 2010 at 12:58 PM, Pratik <prati...@gmail.com> wrote:
>> I swear I had fixed this. Will have another look.
>
> It may be fixed in edge, I'm working off beta4. Will switch to edge
> and double check.
>
> —P
If you are using 1.9.2, you may also want to check which revision of
Ruby you're using. (Yes, revision as it the SVN trunk number.) There
was a constant lookup bug for a little while which may have
contributed to this problem, too.
-Rob
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>
>
>
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> Paul Campbell
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Paul Campbell
On Fri, Jul 2, 2010 at 2:03 PM, Ernie Miller <er...@metautonomo.us> wrote:
> Pratik, seems like you're right. A quick glance at the scoped method looks
> like it should be deferring any attempt to actually call a condition until
> the scope is used, not when it's defined. From Paul's trace, it looks like
> he is running into an issue caused by the devise_for stuff in his routes
> file. (Sorry José!) It may also be related to the questionable choice of
Sorry about the false alarm ... removing "devise_for" in the routes
"fixes" this, so it looks like it is a devise issue.
Definitely something I can live with in the short term.
> defining an attribute based on a Ruby keyword (private).
I'm pretty sure this isn't the case, since there's no "private" method
name. Interestingly, it's very difficult to come up for a name in this
that isn't a potential collision.
"private" and "public" being the most obvious choices, even
"anonymous" doesn't really work.
Anyway, thanks for your help.
—P
Ernie Miller
defining an attribute based on a Ruby keyword (private).
I'm pretty sure this isn't the case, since there's no "private" method
name. Interestingly, it's very difficult to come up for a name in this
that isn't a potential collision.
"private" and "public" being the most obvious choices, even
"anonymous" doesn't really work.
Anyway, thanks for your help.
—P
Ernie Miller
On Jul 2, 2010, at 9:11 AM, Paul Campbell wrote:
>
>
> I'm pretty sure this isn't the case, since there's no "private" method
> name. Interestingly, it's very difficult to come up for a name in this
> that isn't a potential collision.
I misspoke re "private" vs "public". I'm now on my second cup of coffee so fully qualified to respond. :)
I think this test lends credence to my suspicion, though:
ruby-1.9.2-head > class Tester
ruby-1.9.2-head ?> def self.public
ruby-1.9.2-head ?> puts "Hey, I'm not a keyword, I'm a class method!"
ruby-1.9.2-head ?> end
ruby-1.9.2-head ?> end
=> nil
ruby-1.9.2-head > Tester.instance_eval do
ruby-1.9.2-head > public
ruby-1.9.2-head ?> def blah
ruby-1.9.2-head ?> puts "blah"
ruby-1.9.2-head ?> end
ruby-1.9.2-head ?> end
Hey, I'm not a keyword, I'm a class method!
=> nil
Try renaming your scope and see if the issue persists.
Paul Campbell
> ruby-1.9.2-head > public
> ruby-1.9.2-head ?> def blah
> ruby-1.9.2-head ?> puts "blah"
> ruby-1.9.2-head ?> end
> ruby-1.9.2-head ?> end
> Hey, I'm not a keyword, I'm a class method!
> => nil
>
> Try renaming your scope and see if the issue persists.
I had tried that, it did persist : José assures me he's fixed the
issue in Rails edge
(http://github.com/plataformatec/devise/issues/issue/357/#comment_296820),
so I'm switching to that!
—P