Skip to main content

Check if key exists in hash in rails

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 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.
Syntax     Description
hash#has_key? 'sample'     This will return true/false by checking if key 'sample' exists in hash object for which the method is invoked

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?
Parameter     Hash#has_key?     Array#include
Time Complexity     o(1) operation     o(n) operation.
Access Type     Accesses Hash[key] if it returns any value then true is returned to the Hash#has_key? call     Iterates through each element of the array till it finds the value in Array

You can find more about ruby hashes and various methods that can be used with hashes on apidock. So we have learned how to check if key exists in hash for Ruby language and compared it with include operation of array and found has_key is is faster as it is o(1) lookup as explained above.

Comments

Popular posts from this blog

Gem::LoadError (Specified 'mysql2' for database adapter, but the gem is not loaded. Add `gem 'mysql2'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord).?

Gem::LoadError (Specified 'mysql2' for database adapter, but the gem is not loaded. Add `gem 'mysql2'` to your Gemfile (and ensure its version is at the minimum required by ActiveRecord).) In rails?


1)change the gemfile in mysql version
 gem 'mysql2'

2)Change to mysql2 version
 gem 'mysql2','0.3.20'

Active Scaffold : Add radio buttons to your form ruby on rails ?

Active Scaffold : Add radio buttons to your form ruby on rails ?

The way to add radio buttons to your active scaffold create/update from is as shown below

#Controller

class UsersController < ApplicationController
active_scaffold :user do |config|
config.label = “Users”
config.columns = [:name, :gender]
config.columns[:gender].form_ui = :radio
config.columns[:gender].options[:options] = [['Male', '1'], ['Female','2']]
end
end

Get the Current url in ruby on rails

request.refererrequest.fullpathrequest.fullpath.split("?")[0]request.referer or request.env['HTTP_REFERER'] your controller to get the referer url. 

--------------------
request.original_url
request.url
request.host_with_port
<link rel="canonical" href="<%= request.url %>" />
<%=request.path%>
How can I get the current absolute URL in my Ruby on Rails view?
The request.request_uri only returns the relative URL.
request.env['REQUEST_URI']

 For Rails 3.2 or Rails 4 you should use request.original_url to get the current URL. More detail.

For Rails 3: You want "#{request.protocol}#{request.host_with_port}#{request.fullpath}", since request.url is now deprecated.

For Rails 2: You want request.url instead of request.request_uri. This combines the protocol (usually http://) with the host, and request_uri to give you the full address