In Ruby on Rails Programming you might have to check if key exists in hash and based on that you might have to perform other operation. There is a simple way to detect if key exists in particular hash.

Ruby Hashes

Ruby hash contains Key-Value pairs. In Ruby, you can create a simple hash as follows,

my_hash = {}

Above code will initialize empty hash. Let’s add some key value pair in the my_hash

my_hash['name'] = 'Ruby in Rails'

The above code will add ‘name’ key and ‘Ruby in Rails’ as it’s value. Let’s add one more key-value pair in the my_hash

my_hash['type'] = 'Ruby Programming Tutorials'

Now,

How to check if key exists in hash

You can check if particular key exists in a hash or not by using has_key? method available for the hash object in ruby.

my_hash.has_key? 'name'
=> true

This will return true as name key exists in the my_hash hash

my_hash.has_key? 'abc'
=> false

Above code returns false as my_hash doesn’t contain any key with named abc

Performance of Hash#has_key? versun Array#include?

Conclusion

You can find more about ruby hashes and various methods that can be used with hashes on apidock. We learned how to check if key exists in a hash for Ruby language and compared it with include operation on arrays.

The has_key is faster as it is o(1) lookup as explained above.