# Empty string and nil values help needed **URL:** \ **Category:** Rails\ **Created:** [July 21, 2009, 4:18pm UTC](https://www.ruby-forum.com/t/empty-string-and-nil-values-help-needed/172435 "2009-07-21T16:18:46Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![cswebgrl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/edb3f5/32.png) [@cswebgrl](https://www.ruby-forum.com/u/cswebgrl)\ **Post date:** [July 21, 2009, 4:18pm UTC](https://www.ruby-forum.com/t/empty-string-and-nil-values-help-needed/172435/1 "2009-07-21T16:18:46Z")
I have done many variations of this code. Essentially I want this to be true. assert\_equal ‘’, Org.field\_for(nil).display This is a polymorphic relationship. # fieldable.rb def field\_for(purpose) self.fields.find( :first, :conditions =\> [“purpose LIKE ?”, “#{purpose}”], :order =\> ‘position asc’) end # def # field.rb def display str = “” field.to\_s unless search.blank? str end Can someone help tell me what I’m doing wrong and why I can’t produce an empty string? I had thought that nil.to\_s created an empty string, but just writing the following didn’t work either. def display field.to\_s end Thanks! ---
**Author:** ![cswebgrl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/edb3f5/32.png) [@cswebgrl](https://www.ruby-forum.com/u/cswebgrl)\ **Post date:** [July 21, 2009, 5:18pm UTC](https://www.ruby-forum.com/t/empty-string-and-nil-values-help-needed/172435/2 "2009-07-21T17:18:08Z")
On Jul 21, 2009, at 7:18 AM, Cs Webgrl wrote: > I have done many variations of this code. Essentially I want this > to be > true. > > assert\_equal ‘’, Org.field\_for(nil).display You’ve overridden it so I doubt this is the problem, but display is a built-in method at a very basic level (somewhere near inspect) so maybe that’s messing you up in case you aren’t overriding it correctly. > This is a polymorphic relationship. > > # fieldable.rb > > def field\_for(purpose) > self.fields.find( > :first, > :conditions =\> [“purpose LIKE ?”, “#{purpose}”], Are you sure you didn’t mean [“purpose LIKE ?”, purpose] There’s no reason to quote the second argument. Although I don’t know what Rails does when you pass in nil to conditions like that. Maybe it doesn’t like that. > str > end > > Can someone help tell me what I’m doing wrong and why I can’t > produce an > empty string? I had thought that nil.to\_s created an empty string, > but > just writing the following didn’t work either. It does. > > nil.to\_s > > =\> “” So, something else is wrong somewhere… ---
**Author:** ![cswebgrl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/edb3f5/32.png) [@cswebgrl](https://www.ruby-forum.com/u/cswebgrl)\ **Post date:** [July 21, 2009, 5:42pm UTC](https://www.ruby-forum.com/t/empty-string-and-nil-values-help-needed/172435/3 "2009-07-21T17:42:55Z")
Philip H. wrote: > You’ve overridden it so I doubt this is the problem, but display is a > built-in method at a very basic level (somewhere near inspect) so > maybe that’s messing you up in case you aren’t overriding it correctly. I changed the method name to display\_field, but the test still fails. > Are you sure you didn’t mean [“purpose LIKE ?”, purpose] There’s no > reason to quote the second argument. Although I don’t know what Rails > does when you pass in nil to conditions like that. Maybe it doesn’t > like that. I modified this also and the test passes/fails both ways. > > > nil.to\_s > > > =\> “” > > So, something else is wrong somewhere… Tests run on this method work fine if I’m not passing in a nil value. I’m not quite sure where else to look. Any thoughts? Thanks. ---
**Author:** ![cswebgrl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/edb3f5/32.png) [@cswebgrl](https://www.ruby-forum.com/u/cswebgrl)\ **Post date:** [July 21, 2009, 7:24pm UTC](https://www.ruby-forum.com/t/empty-string-and-nil-values-help-needed/172435/4 "2009-07-21T19:24:12Z")
James B. wrote: > What does the application stack trace say? Is there an easy way to generate this from a test? ---
**Author:** ![cswebgrl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/edb3f5/32.png) [@cswebgrl](https://www.ruby-forum.com/u/cswebgrl)\ **Post date:** [July 21, 2009, 7:47pm UTC](https://www.ruby-forum.com/t/empty-string-and-nil-values-help-needed/172435/5 "2009-07-21T19:47:28Z")
Cs Webgrl wrote: > James B. wrote: > > > What does the application stack trace say? > > Is there an easy way to generate this from a test? The trace should be in test.log. ## Best, Marnen Laibow-Koser [http://www.marnen.org](http://www.marnen.org) removed\_email\_address@domain.invalid ---
**Author:** ![cswebgrl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/edb3f5/32.png) [@cswebgrl](https://www.ruby-forum.com/u/cswebgrl)\ **Post date:** [July 21, 2009, 9:25pm UTC](https://www.ruby-forum.com/t/empty-string-and-nil-values-help-needed/172435/6 "2009-07-21T21:25:26Z")
Marnen Laibow-Koser wrote: > The trace should be in test.log. This code is in a plugin. To run tests, I’m running them directly out of the vendor/plugins directory. Any ideas how to write a test.log there? ---
**Author:** ![cswebgrl](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/c/edb3f5/32.png) [@cswebgrl](https://www.ruby-forum.com/u/cswebgrl)\ **Post date:** [July 21, 2009, 7:12pm UTC](https://www.ruby-forum.com/t/empty-string-and-nil-values-help-needed/172435/7 "2009-07-21T19:12:11Z")
On Jul 21, 11:42 am, Cs Webgrl [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Tests run on this method work fine if I’m not passing in a nil value. > I’m not quite sure where else to look. Any thoughts? What does the application stack trace say?