Ruby合并哈希键值

Question

I have two hashes: one containing a list of hosts and another with network data. I want to create a third hash that combines the host data with the network data.

Here's an example of the two hashes:

{
   :myhost1=>{:name=>"hostname1", :trust=>:net80, :dmz=>:net81},
   :myhost2=>{:name=>"anotherhost", :trust=>:net80, :dmz=>:net82}
}

{
   :net80=>{:range=>"192.168.0.0", :gateway=>"192.168.0.1", :netmask=>"255.255.255.0"}, 
   :net81=>{:range=>"192.168.1.0", :gateway=>"192.168.1.1", :netmask=>"255.255.255.0"}, 
   :net82=>{:range=>"192.168.3.0", :gateway=>"192.168.2.1", :netmask=>"255.255.248.0"}
}

The merge would be with trust and dmz - replacing the key in the host info with the value of the associated key in the network info. The merged hash would be this:

{
   :myhost1=>{:name=>"hostname1", :trust=>{:range=>"192.168.0.0", :gateway=>"192.168.0.1", :netmask=>"255.255.255.0"}, :dmz=>{:range=>"192.168.1.0", :gateway=>"192.168.1.1", :netmask=>"255.255.255.0"}}, 
   :myhost2=>{:name=>"anotherhost", :trust=>{:range=>"192.168.0.0", :gateway=>"192.168.0.1", :netmask=>"255.255.255.0"}, :dmz=>{:range=>"192.168.3.0", :gateway=>"192.168.2.1", :netmask=>"255.255.248.0"}}
}

EDIT: I've updatd the host hash to use symbols to make the merge easier.

Answer 1

The idea here is you can convert the initial structure by expanding certain keys, or not expanding others depending on the overall shape of that thing. Here's an example:

hosts = {
   myhost1: {:name=>"hostname1", :trust=>"net80", :dmz=>"net81"},
   myhost2: {:name=>"anotherhost", :trust=>"net80", :dmz=>"net82"}
}

nets = {
   net80: {:range=>"192.168.0.0", :gateway=>"192.168.0.1", :netmask=>"255.255.255.0"}, 
   net81: {:range=>"192.168.1.0", :gateway=>"192.168.1.1", :netmask=>"255.255.255.0"}, 
   net82: {:range=>"192.168.3.0", :gateway=>"192.168.2.1", :netmask=>"255.255.248.0"}
}

hosts.collect do |name, entry|
  [
    name,
    entry.map do |key, value|
      case (key)
      when :name
        [ key, value ]
      else
        [ key, nets[value.to_sym] ]
      end
    end.to_h
  ]
end

# => {:myhost1=>{:name=>"hostname1", :trust=>{:range=>"192.168.0.0", ...

This would be marginally less messy if you had trust: :net80 to keep symbol-symbol matching.

Answer 2

hosts = {
  :myhost1=>{ :name=>"hostname1",   :trust=>:net80, :dmz=>:net81 },
  :myhost2=>{ :name=>"anotherhost", :trust=>:net80, :dmz=>:net82 }
}

network = {
  :net80=>{ :range=>"192.168.0.0", :gateway=>"192.168.0.1",
            :netmask=>"255.255.255.0" }, 
  :net81=>{ :range=>"192.168.1.0", :gateway=>"192.168.1.1",
            :netmask=>"255.255.255.0" }, 
  :net82=>{ :range=>"192.168.3.0", :gateway=>"192.168.2.1",
            :netmask=>"255.255.248.0" }
}

Here are two approaches that could be used.

#1 Merge the hash with itself, changing some values

hosts.merge(hosts) { |*,g|
  g.merge(trust: network[g[:trust]], dmz: network[g[:dmz]]) }
  #=> {
  #     :myhost1=>{
  #       :name =>"hostname1",
  #       :trust=>{ :range=>"192.168.0.0", :gateway=>"192.168.0.1",
  #                 :netmask=>"255.255.255.0" },
  #       :dmz  =>{ :range=>"192.168.1.0", :gateway=>"192.168.1.1",
  #                 :netmask=>"255.255.255.0" }
  #     }, 
  #     :myhost2=>{
  #       :name =>"anotherhost",
  #       :trust=>{ :range=>"192.168.0.0", :gateway=>"192.168.0.1",
  #                 :netmask=>"255.255.255.0" },
  #       :dmz  =>{ :range=>"192.168.3.0", :gateway=>"192.168.2.1",
  #                 :netmask=>"255.255.248.0" }
  #     }
  #   }

#2 Build a hash

hosts.each_with_object({}) { |(host,g), h|
  h[host] = { :name =>g[:name],
              :trust=>network[g[:trust]],
              :dmz  =>network[g[:dmz]] } }
  #=> same as for #1

Answer 3

Try this

hosts.each_value do |hash| 
  hash[:trust] = nets[hash[:trust]]
  hash[:dmz] = nets[hash[:dmz]]
end

NB, this mutates the hosts data structure.

Answer 4

With Ruby 2.4 long-awaited transform_values , it's possible to design a solution that would work in many other cases :

hosts =
  {
    myhost1: { name: 'hostname1', trust: :net80, dmz: :net81 },
    myhost2: { name: 'anotherhost', trust: :net80, dmz: :net82 }
  }

networks = {
  net80: { range: '192.168.0.0', gateway: '192.168.0.1', netmask: '255.255.255.0' },
  net81: { range: '192.168.1.0', gateway: '192.168.1.1', netmask: '255.255.255.0' },
  net82: { range: '192.168.3.0', gateway: '192.168.2.1', netmask: '255.255.248.0' }
}

class Hash
  #{lost: :key}.translate(key: :clef) #=> {:lost=>:clef}
  def translate(dict)
    transform_values do |v|
      if v.is_a?(Hash)
        v.translate(dict)
      elsif dict.key?(v)
        dict[v]
      else
        v
      end
    end
  end
end


require 'pp'
pp hosts.translate(networks)
# {:myhost1=>
#   {:name=>"hostname1",
#    :trust=>
#     {:range=>"192.168.0.0",
#      :gateway=>"192.168.0.1",
#      :netmask=>"255.255.255.0"},
#    :dmz=>
#     {:range=>"192.168.1.0",
#      :gateway=>"192.168.1.1",
#      :netmask=>"255.255.255.0"}},
#  :myhost2=>
#   {:name=>"anotherhost",
#    :trust=>
#     {:range=>"192.168.0.0",
#      :gateway=>"192.168.0.1",
#      :netmask=>"255.255.255.0"},
#    :dmz=>
#     {:range=>"192.168.3.0",
#      :gateway=>"192.168.2.1",
#      :netmask=>"255.255.248.0"}}}