gistfile1.rb

require "awesome_print"

def make_hash(keys, value)
  keys.empty? ? value : { keys.shift => make_hash(keys, value) }
end

data = {
  "80e33bc0-1b9a-0130-d2fb-38f6b113e413:data:message:name" => "max",
  "80e33bc0-1b9a-0130-d2fb-38f6b113e413:data:text" => "bla",
  "80e33bc0-1b9a-0130-d2fb-38f6b113e413:data:message:line:x" => 123
}

@json = {}
data.each do |key, value|
  @json = @json.merge(make_hash(key.split(':'), value))
end

ap @json

Output:

{
    "80e33bc0-1b9a-0130-d2fb-38f6b113e413" => {
        "data" => {
            "message" => {
                "line" => {
                    "x" => 123
                }
            }
        }
    }
}

Expected:

{
    "80e33bc0-1b9a-0130-d2fb-38f6b113e413" => {
        "data" => {
            "message" => {
                "name" => "max"
                "line" => {
                    "x" => 123
                }
            },
            "text" => "bla"
        }
    }
}

This one works:

require "awesome_print"

def make_hash(keys, value)
  keys.empty? ? value : { keys.shift => make_hash(keys, value) }
end

def recurse_merge(a,b)
  a.merge(b) do |_,x,y|
    (x.is_a?(Hash) && y.is_a?(Hash)) ? recurse_merge(x,y) : [*x,*y]
  end
end

data = {
  "80e33bc0-1b9a-0130-d2fb-38f6b113e413:data:message:name" => "max",
  "80e33bc0-1b9a-0130-d2fb-38f6b113e413:data:text" => "bla",
  "80e33bc0-1b9a-0130-d2fb-38f6b113e413:data:message:line:x" => 123
}

@json = {}
data.each do |key, value|
  single_json = make_hash(key.split(':'), value)
  @json = recurse_merge(@json, single_json)
end

ap @json

Disclaimer: All credit goes to the big database of stackoverflow :-)