deep_fetch

Easily fetch values from nested ruby hashes.

Installation

Add this line to your application's Gemfile:

gem 'deep_fetch'

And then execute:

bundle

Let's say we have a big hash:

example = {
  :foo => {
    :bar => [ 'a', 'b', 'c' ],
    :baz => :boo
  }
}

We can fetch a value under :foo, :baz easily:

example.deep_fetch(:foo, :baz) # => :boo

If the key does not exist, we receive KeyError exception, just like using Hash#fetch

example.deep_fetch(:foo, :boo) # => KeyError: key not found: :boo

Specify a default value to be returned if key is missing in a block:

example.deep_fetch(:foo, :boo) { "not found" } # => "not found"

Lastly, if the hash contains nested array, we can get values from it by providing an integer:

example.deep_fetch(:foo, :bar, 1) # => 'b'

The gem might be useful when working with deeply nested hashes, e.g. API responses.

By using Hash#deep_fetch we can assert that the response contains the key, making it fail loud otherwise.