CODEWITHSUNDEEP
ruby-on-railsrubymethod-missing
legendary_rob
legendary_rob

Reputation: 13012

Rails Method_missing to throw back values from a hash

i am trying to write a method_missing method, so that when i run a method it must hit the hash and look at the keys, if it finds a match to return the value. and continue. the hash is populated from a sql query that i wrote so the values are never constant.

an example would be like 

 @month_id.number_of_white_envelopes_made

in the hash

 @data_hash[number_of_white_envelopes_made] => 1

so @month_id will return 1. i have never worked with it before, not much material out there using hashes as the fall back with method missing

EDIT: sorry i forgot to say if it doesnt find the method in the hash then it can continue down to no method error

EDIT: alright so i was hacking away and this is what i have come up with

 def method_missing(method)
   if @data_hash.has_key? method.to_sym
     return @data_hash[method]
   else
     super
   end
 end

is there a better way?

Upvotes: 0

Views: 2217

Answers (2)

akuhn
akuhn

Reputation: 27813

The shortest is

class Hash
  def method_missing(sym,*)
    fetch(sym){fetch(sym.to_s){super}}
  end
end

which first tries hash[:key] and then hash["key"]

Upvotes: 2

Alberto Santini
Alberto Santini

Reputation: 6562

What about something like:

def method_missing(method_sym, *arguments, &block)
  if @data_hash.include? method_sym
    @data_hash[method_sym]
  else
    super
  end
end

And always remember to add the corresponding respond_to? to your object:

def respond_to?(method_sym, include_private = false)
  if @data_hash.include? method_sym
    true
  else
    super
  end
end

Upvotes: 6

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