Ruby - strings operation

Question

I have this simple helper:

def printe_result(data)
  a_var = ('<a href="http://'+data.a_value+'>A</a>' unless (data.a_value.nil? || data.a_value.empty?))
  b_var = ('<a href="http://'+data.b_value+'>B</a>' unless (data.b_value.nil? || data.b_value.empty?))
  c_var = ('<a href="http://'+data.c_value+'>C</a>' unless (data.c_value.nil? || data.c_value.empty?))

  return ...
end

a_value, b_value, c_value I am taking from database. If the values are strings, I want to save them into the respective variable and then all variables return as one string with the values separated by comma, for example:

"<a href=http://a>A</a>, <a href=http://b>B</a>, <a href=http://c>C</a>"

How can I merge the variables only if they exist?

Andrew Marshall · Accepted Answer · 2012-04-07 16:48:10Z

4

def printe_result(data)
  { 'A' => data.a_value, 'B' => data.b_value, 'C' => data.c_value }.map do |name, val|
    "<a href='http://#{val}'>#{name}</a>" unless val.blank?
  end.compact.join(',')
end

answered Apr 7, 2012 at 16:48

Andrew Marshall

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1 Comment

Andrew Marshall Over a year ago

Note that this assumes that you're using Rails or have required ActiveSupport's core extensions, as that's where blank? comes from. If not it can be replaced with val.nil? || val.empty?. I assumed you have Rails because of the URLs & the database reference.

Frederick Cheung · Accepted Answer · 2012-04-07 16:45:00Z

2

Something like

 [[a_value,'A'],[b_value,'B'],[c_value,'C']].select {|(value, label)| !value.blank?}.
    map {|(value, label)| %q[<a href="http://#{value}">#{label}</a>]}.join(',')

Ought to do the trick: use select to eliminate pairs with blank labels, map to turn the label into the desired text and join to join the strings together.

answered Apr 7, 2012 at 16:45

Frederick Cheung

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1 Comment

Andrew Marshall Over a year ago

It's a shame the syntax highlighter gets so confused on string literals.

alex · Accepted Answer · 2012-04-07 16:37:26Z

0

I hope i get your question right - you can use the defined?(variable_name) method to check if a variable has been defined.

I hope this helps!

answered Apr 7, 2012 at 16:37

alex

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1 Comment

Dominik Honnef Over a year ago

defined? would not help in this case: gist.github.com/e76db37917284e30dbb8

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