Question

Is there an easy or elegant way to merge two hashes without overwriting duplicate keys?

That is, if the key is present in the original hash I don’t want to change its value.

Answer 1

If you have two hashes, options and defaults, and you want to merge defaults into options without overwriting existing keys, what you really want to do is the reverse: merge options into defaults:

options = defaults.merge(options)

Or, if you’re using Rails you can do:

options.reverse_merge!(defaults)