Dealing with nil output

ruby-talk
1

Hi, i use the following code to obtain data from my csv file and
transfer it into a class:

ef = EfficiencyE.new
pp ef.blank = fields[1].tr_s('"', '').strip

i put pp to see the output and the output says:

""
"Efficiency (Energy)"
""
"Turn-off unnecessary lights/equipment"
C:/Users/Hekmatyer/Documents/NetBeansProjects/Nizam_BARU/lib/final.rb:574:in
`block in <main>': undefined method `tr_s' for nil:NilClass
(NoMethodError)
        from
C:/Users/Hekmatyer/Documents/NetBeansProjects/Nizam_BARU/lib/final.rb:559:in
`each_line'
        from
C:/Users/Hekmatyer/Documents/NetBeansProjects/Nizam_BARU/lib/final.rb:559:in
`<main>'

I think i know the problem because there are empty content in my csv
file. So how do i deal with this empty (nil) content?

Nizam

···

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2

Ideally, you would be able to fix your CSV data to avoid the issue. :slight_smile:
Assuming that's not an option, you could do something like the following:

pp ef.blank = fields[1].to_s.tr_s('"', '').strip

For the fields that are not nil, to_s will be called, but since they
should be strings already, that's effectively a no-op. For nil values,
the to_s method will return an empty string.

If you need to use something other than an empty string as a replacement
for nil values (such as using "Error!" instead), you could do this:

pp ef.blank = (fields[1] || "Error!").tr_s('"', '').strip

The string "Error!" will be used in place of any nil field while non-nil
fields will be used directly.

-Jeremy

···

On 02/04/2011 08:34 PM, Kamarulnizam Rahim wrote:

Hi, i use the following code to obtain data from my csv file and
transfer it into a class:

ef = EfficiencyE.new
pp ef.blank = fields[1].tr_s('"', '').strip

i put pp to see the output and the output says:

""
"Efficiency (Energy)"
""
"Turn-off unnecessary lights/equipment"
C:/Users/Hekmatyer/Documents/NetBeansProjects/Nizam_BARU/lib/final.rb:574:in
`block in <main>': undefined method `tr_s' for nil:NilClass
(NoMethodError)
        from
C:/Users/Hekmatyer/Documents/NetBeansProjects/Nizam_BARU/lib/final.rb:559:in
`each_line'
        from
C:/Users/Hekmatyer/Documents/NetBeansProjects/Nizam_BARU/lib/final.rb:559:in
`<main>'

I think i know the problem because there are empty content in my csv
file. So how do i deal with this empty (nil) content?

3

Thanks Jeremy!!

···

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Posted via http://www.ruby-forum.com/.