How to check if a key exists in a Ruby hash?

Question

I am using search of Net::LDAP, the returned entry is something like this.

#<Net::LDAP::Entry:0x7f47a6491c00 @myhash= {:loginshell=>["/bin/bash"], :cn=>["M... R..."], :homedirectory=>["/mnt/home/m..."], :uid=>["m..."], :userpassword=>["{CRYPT}$1$3zR/C...$R1"], ... }>

I tried to do the following, but failed.

(1)

e = entry.to_hash e.has_key? "uid"

(2)

entry.has_key? "uid"

The first error says "to_hash" undefined, the second "has_key" undefined. Then I really don't know how to do it, basically I want to find if "uid" is present and if so get its correspondent value.

Thank you very much for the tip.

BTW, it only responds to "entry.uid", but if the search key is provided as a string, how to do that? for example,

def get_value(key) if entry has key return key's value end end

scaryguy · Accepted Answer · 2014-03-26 01:13:17Z

35

:uid is a Symbol. That's not a String.

try this:

e.has_key? :uid

answered Mar 26, 2014 at 1:13

scaryguy

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5 Comments

John Dibling Over a year ago

If all you have is a string, you could also "uid".to_sym

user180574 Over a year ago

"has_key" not defined, but "to_sym" is helpful. Thanks.

scaryguy Over a year ago

has_key? -be aware of the question mark- is a method of any instance of Hash class. It can not be undefined unless you're using it something different than a Hash instance.

user180574 Over a year ago

That's why I puzzled, I don't know what it is. I end up using "entry.each do |k, v|" to break into key-value pair.

scaryguy Over a year ago

It's as simple as adding a .class to any object to know it's class type. Do a e.class and you'll see what it is.

JordanD · Accepted Answer · 2014-03-26 01:19:49Z

The key "uid" doesn't exist. Try

e = Entry.new.myhash e.has_key?(:uid)

That should return true. If that gives you an error, the problem might lie in your class. Make sure that myhash is defined in the initialize method, and that you use a getter method (or attr_reader) to be able to access the variable. You could use

attr_reader :myhash

right before the initialize method.

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