Rails given a string, how to convert it to an array in ruby?

Question

my table has Attachment.attachment_content_type which is of type string. Values look like this:

[]
[image/png]
[application/msword, application/word, application/x-msword, application/x-word, text/plain]

What I want to do is get the first item if any.

I'm trying with:

attachment.attachment_content_type[0]

But that just returns [ and not 'application/msword'

Should I use a split or is there a better way with ruby on rails to tell rails this is an array? Thanks

The answers below are correct solutions. I'm a little curious about why these are being stored in a somewhat difficult-to-parse string. If you control the code, consider using ActiveRecord's serialize to store/retrieve a real Ruby array, or consider creating a has_many relationship to another table (probably overkill for this). — Jim Stewart
– Jim Stewart, Commented Dec 5, 2012 at 21:25

Philip Hallstrom · Accepted Answer · 2012-12-05 21:21:17Z

3

$ cat foo.rb 

strings = [
  "[]",
  "[image/png]",
  "[application/msword, application/word, application/x-msword, application/x-word, text/plain]"
]

strings.each do |string|
  array = string[1...-1].split(/[\s,]+/)
  puts array[0]
end

$ ruby foo.rb 

image/png
application/msword

answered Dec 5, 2012 at 21:21

Philip Hallstrom

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1 Comment

Tom Harrison Over a year ago

By way of explanation for Rachel, the value "[]" and others are Strings, so must be parsed and turned into arrays.

rohit89 · Accepted Answer · 2012-12-05 21:27:21Z

1

attachment.attachment_content_type[1..-2].split(',').map(&:strip) will return the contents of the string as an array.

answered Dec 5, 2012 at 21:27

rohit89

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Comments

knownasilya · Accepted Answer · 2012-12-05 21:36:35Z

0

Try using gsub! and scan.

mimetypes.gsub!(/([\[\]])/, '')
mime_array = mimetypes.scan(/, /)

See the String API for more interesting methods along with Rubular for regex testing :)

answered Dec 5, 2012 at 21:36

knownasilya

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