How to find a hash key containing a matching value

Matheus Mello
Matheus Mello
September 2, 2023
Cover Image for How to find a hash key containing a matching value

🗝️ Finding a Hash Key with a Matching Value in Ruby 🚀

Are you tired of writing long and complex scripts just to find the key in a hash that matches a specific value? Look no further! In this blog post, we will explore an easy and quick way to obtain the key in Ruby, without the need for a multi-line script. 🎉

The Problem 😕

Let's say you have a hash called clients, and you want to find the key that corresponds to a specific value of client_id. In our example, we want to retrieve the key for the value "2180". How can we achieve this without any hassle? Let's find out! 💪

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

The Solution 💡

To extract the key containing the matching value, we can make use of the Hash#key method in Ruby. This method accepts a value as an argument and returns the corresponding key in the hash. Here's how you can do it:

clients.key({"client_id" => "2180"})

In this case, calling clients.key({"client_id" => "2180"}) will return "orange" as the output. It's as simple as that! 🎈

An Alternative Solution 🔄

Alternatively, if you would like to avoid passing the entire value as an argument to Hash#key, you can make use of the Enumerable#find method along with a block. Here's how you can implement it:

clients.find { |key, value| value["client_id"] == "2180" }&.first

This code snippet achieves the same result as before. It uses the find method to iterate through each key-value pair in the hash and checks if the client_id matches the desired value. The &.first part ensures that if no match is found, it returns nil instead of raising an error.

A Handy Tip ✨

If you find yourself needing to perform this operation frequently, you can encapsulate the solution into a method for reusability. For example:

def find_key_by_value(hash, value)
  hash.key(value)
end

Now, you can easily call find_key_by_value(clients, {"client_id" => "2180"}) to obtain the desired key.

Get the Key to Unlock Your Solution! 🔑

Finding a hash key containing a matching value has never been easier! Say goodbye to writing multi-line scripts and hello to simplicity. Try out the code snippets provided and let us know how they work for you. If you have any questions or alternative approaches to share, feel free to leave a comment below. Happy coding! 😊

Note: Don't forget to replace clients with your actual hash variable name when implementing these solutions in your code.

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