"singleton can't be dumped," but not using singleton

Rails
1

An action handler (select_person_by_name) in my controller class assigns
into session, and then does a redirect_to. I get the error “TypeError
(singleton can’t be dumped):” followed by a stack trace that doesn’t
cross my code.

Google tells me this is ordinarily caused by assigning a singleton
instance into session, but what I’m assigning is an ordinary String.
This is verified by logging the value and its class.

Further, the log shows a “Redirected to” line to the URL I expect from
by redirect_to. The TypeError is reported from a SECOND attempt to
process the select_person_by_name handler.

The parameters for both invocations of select_person_by_name are as I
expect from what I did in the view.

select_person_by_name appears in my source twice: Once to def it, and
once as the :action in the form that invokes it.

Could someone please give me a further lead?

-- F

===
fritzanderson:calert2 fritza$ ruby -v
ruby 1.8.6 (2008-03-03 patchlevel 114) [universal-darwin9.0]
fritzanderson:calert2 fritza$ rails --version
Rails 1.2.6

Here is the code, boiled down. Values, classes, etc., are verified by
logger calls (omitted):

class AdminController < ApplicationController
def select_person_by_name
# Here @people is set to be an Array with one element
case @people.size
# Other branches omitted
when 1
person = @people[0]
session[:focused_cnetid] = person.principal.cnetid
# person.principal.cnetid is as expected, it’s a String,
# and it’s generated from external data. (“fritza”, nothing
special)
redirect_to :controller => :people, :action => :show, :id =>
person
# person.id is as expected.
end #case
end # select_person_by_name
end # class

2

A further development: If I log
person.principal.cnetid.singleton_methods, I get “ber_identifier,” which
I assume comes from the string’s originating in ruby-net-ldap. What’s
the best way to strip that out?

-- F
3

On Dec 5, 10:42 pm, Fritz A. [email protected]
wrote:

A further development: If I log
person.principal.cnetid.singleton_methods, I get “ber_identifier,” which
I assume comes from the string’s originating in ruby-net-ldap. What’s
the best way to strip that out?

Just dup the string or something like that ?

Fred

4

Frederick C. wrote:

On Dec 5, 10:42�pm, Fritz A. [email protected]
wrote:

A further development: If I log
person.principal.cnetid.singleton_methods, I get “ber_identifier,” which
I assume comes from the string’s originating in ruby-net-ldap. What’s
the best way to strip that out?

Just dup the string or something like that ?

That in fact was the solution. Thank you.

My own attempt (it succeeded) was
(“%s” % person.principal.cnetid)
which is insane.

Further note: Another approach I found via Google involved this:

===
class String
def strip_ber_identifier
class << self; undef :ber_identifier; end
end
end

This gets into the singleton-method space and undefines the offending
method. The problem with this is that Strings that populate LDAP-return
objects from ruby-net-ldap derive their value from ber_identifier.
Stripping the method cuts them loose from the underlying LDAP record and
they come out nil.

-- F