ruby throws exception by ldap search by empty field - ruby

Question

I try to get some information from the LDAP (internal AD). Everything work as it should, except when I want get the data out of an empty field.
require 'net/ldap'
...
def getDatafromAD(ad_hostname,ad_dn,ad_password,username)
ldap = Net::LDAP.new :host => ad_hostname, :port => 389, :auth => {
:method => :simple,
:username => ad_dn,
:password => ad_password }
filter = Net::LDAP::Filter.eq("cn", username)
treebase = "ou=myOU,dc=example,dc=com"
attrs = ["givenName", "mobile", "mail", "cn", "sn", "person"]
ldap.search( :base => treebase, :filter => filter, :attributes => attrs ) do |entry|
puts "UID: #{entry.dn}"
puts "#{entry.cn.first}: Surename: #{entry.sn.first} Givenname: #{entry.givenName.first} Mail: #{entry.mail.first} Mobile: #{entry.mobile.first}"
end
end
This is running fine until one field is empty (in this case mobile):
Traceback (most recent call last):
16: from query_userdata.rb:79:in `<main>'
15: from query_userdata.rb:79:in `each'
14: from query_userdata.rb:81:in `block in <main>'
13: from query_userdata.rb:58:in `getDatafromAD'
12: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap.rb:782:in `search'
11: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap/instrumentation.rb:19:in `instrument'
10: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap.rb:783:in `block in search'
9: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap.rb:1311:in `use_connection'
8: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap.rb:784:in `block (2 levels) in search'
7: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap/connection.rb:388:in `search'
6: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap/instrumentation.rb:19:in `instrument'
5: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap/connection.rb:399:in `block in search'
4: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap/connection.rb:399:in `loop'
3: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap/connection.rb:445:in `block (2 levels) in search'
2: from /usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap.rb:786:in `block (3 levels) in search'
1: from query_userdata.rb:62:in `block in getDatafromAD'
/usr/share/gems/gems/net-ldap-0.17.0/lib/net/ldap/entry.rb:185:in `method_missing': undefined method `mobile' for #<Net::LDAP::Entry:0x000055c0d912ac60> (NoMethodError)
Can someone please give me a hint how to solve this. My knowledge/XP can not handle this.
I tried with .empty?() to check in advance, but it looks like in the moment of accessing the empty field the exception is here.
If a field is empty I would like to put a custom string ("data not there") in the output. Probably it is just a little switch and I can not find it...
Many thanks!

Answer 1

I've faced the same issue 2 days ago ! I can recommend 2 things:
Access entry attributes through hash keys. Calling missing methods will rise an error, but trying to access a missing key's value will return an empty array
entry[:missing_key]
# => []
entry[:missing_key][0]
# => nil
entry.missing_key.first
# => *** NoMethodError Exception: undefined method `missing_key' for #<Net::LDAP::Entry:0x00005605a06bbf88>
Use a || operator when concatenating potential nil values with a String.
puts "SN: #{(entry[:sn][0] || 'data not there')}" +
"Mobile: #{(entry[:mobile][0] || 'data not there')}" +
"Foo: #{(entry[:foo][0] || 'data not there')}"