How to find a hash key containing a matching value

Question

Given I have the below clients hash, is there a quick ruby way (without having to write a multi-line script) to obtain the key given I want to match the cli

Answer 1

You could use hashname.key(valuename)

Or, an inversion may be in order. new_hash = hashname.invert will give you a new_hash that lets you do things more traditionally.

Answer 2

try this:

clients.find{|key,value| value["client_id"] == "2178"}.first

Answer 3

According to ruby doc http://www.ruby-doc.org/core-1.9.3/Hash.html#method-i-key key(value) is the method to find the key on the base of value.

ROLE = {"customer" => 1, "designer" => 2, "admin" => 100}
ROLE.key(2)

it will return the "designer".

Answer 4

Heres an easy way to do find the keys of a given value:

    clients = {
      "yellow"=>{"client_id"=>"2178"}, 
      "orange"=>{"client_id"=>"2180"}, 
      "red"=>{"client_id"=>"2179"}, 
      "blue"=>{"client_id"=>"2181"}
    }

    p clients.rassoc("client_id"=>"2180")

...and to find the value of a given key:

    p clients.assoc("orange") 

it will give you the key-value pair.