Rails 4：遍历数组

Question

I think I am doing something horribly wrong. I get this error:

TypeError
no implicit conversion of nil into String

if I put this in my View (haml):

...

- ["Greg", "is", "cool", "ya"].each do |tag|
    .tagwrapper
        = link_to tag.to_s.gsub!(/[^0-9A-Za-z]/, ''), '/search?searchtags='+tag.to_s.gsub!(/[^0-9A-Za-z]/, ''), class: 'smaller half-stretched'

...

How am I supposed to do this instead?

Answer 1

gsub! returns nil if no substitutions were performed.

Remove ! so it becomes:

= link_to tag.to_s.gsub(/[^0-9A-Za-z]/, ''), '/search?searchtags='+tag.to_s.gsub(/[^0-9A-Za-z]/, ''), class: 'smaller half-stretched'

APIdock Reference

Answer 2

You should check that gsub! isn't returning nil in the event that no substitutions are made:

# Will make zero passes
replaced_tag = tag.to_s.gsub!(/[^0-9A-Za-z]/, '')
if replaced_tag
    = link_to tag, '/search?searchtags=' + tag, class: 'smaller half-stretched'

Alternatively, in you want to return the string even if no substitutions are made , you can use gsub (with the ! removed):

# Will make four passes, one for each ['Greg', 'is', 'cool', 'ya']
replaced_tag = tag.to_s.gsub(/[^0-9A-Za-z]/, '')
if replaced_tag
    = link_to tag, '/search?searchtags=' + tag, class: 'smaller half-stretched'