Don't destroy last user

Rails
1

How would I stop the last user being deleted.
The following code doesn’t work.

before_destroy :dont_destroy_last_user

Don’t delete user if it the last one

def dont_destroy_last_User
raise “Can’t destroy last user” if User.length < 1
end

2

On 18-feb-2006, at 18:30, Alexander wrote:

How would I stop the last user being deleted.
The following code doesn’t work.

before_destroy :check_if_last_user

private
def check_if_last_user
raise “Last user can’t be deleted” if self.class.count == 1
end

3

Alexander wrote:

How would I stop the last user being deleted.
The following code doesn’t work.

before_destroy :dont_destroy_last_user

Don’t delete user if it the last one

def dont_destroy_last_User
raise “Can’t destroy last user” if User.length < 1
end
Change to:

Don’t delete user if it the last one

def dont_destroy_last_User
raise “Can’t destroy last user” if User.count == 1
end

Untested,but should work

joey__

4

Julian ‘Julik’ Tarkhanov wrote:

On 18-feb-2006, at 18:30, Alexander wrote:

How would I stop the last user being deleted.
The following code doesn’t work.

before_destroy :check_if_last_user

private
def check_if_last_user
raise “Last user can’t be deleted” if self.class.count == 1
end

Thanks

Also ‘raise’ creates quite a ugly error message. Is there any way of
redirecting and using flash instead?

Alex

5

On 18-feb-2006, at 19:06, Alexander wrote:

 raise "Last user can't be deleted" if self.class.count == 1

end

Thanks

Also ‘raise’ creates quite a ugly error message. Is there any way of
redirecting and using flash instead?

I think the neat way would be with an exception catcher

in the model:

class LastUserCantBeDeleted < RuntimeError; end;

… raise LastUserCantBeDeleted if self.class.count == 1

in the controller

begin
@user.destroy!
rescue LastUserCantBeDeleted
flash[:error] = "This is the last one’
redirect_to :referer # or something like that
end

A less neat way would be to return false from the method and thus
stop the callback chain, and then

unless @user.destroy!
flash[:error] = “This is the last one”

… etc

end

6

Julian ‘Julik’ Tarkhanov wrote:

flash[:error] = "This is the last one’
end
This will not work if you have two independent FCGI/SCGI processes
trying
to delete the last user at the same time. Might sound bit extreme, but
its
quite possible for example if the user clicks rapidly the submit button
twice.

You’ll need to wrap the deletion and the counting of users in a
transaction. The first beta release of AWDWR had similar code for
preventing the deletion of the last administrator. Revised version was
simpler not allowing to delete ‘Dave’ user. That’s another alternative.