Let's say I have the following hash:
{ :foo => 'bar', :baz => 'qux' }
How could I dynamically set the keys and values to become instance variables in an object...
class Example
def initialize( hash )
... magic happens here...
end
end
... so that I end up with the following inside the model...
@foo = 'bar'
@baz = 'qux'
?
The method you are looking for is instance_variable_set. So:
hash.each { |name, value| instance_variable_set(name, value) }
Or, more briefly,
hash.each &method(:instance_variable_set)
If your instance variable names are missing the "@" (as they are in the OP's example), you'll need to add them, so it would be more like:
hash.each { |name, value| instance_variable_set("@#{name}", value) }
hash.each {|k,v| instance_variable_set("@#{k}",v)}
hash.each &method(:instance_variable_set), the method instance_variable_set receives the two parameters that it needs?
h = { :foo => 'bar', :baz => 'qux' }
o = Struct.new(*h.keys).new(*h.values)
o.baz
=> "qux"
o.foo
=> "bar"
.new() doing?
Struct.new creates a new class based on the hash keys, and then the second new makes the first object of the just-created class, initializing it to the values of the Hash. See ruby-doc.org/core-1.8.7/classes/Struct.html
require 'ostruct'; h = {:foo => 'foo'}; o = OpenStruct.new(h); o.foo == 'foo'
Struct.new(*hash.keys.map { |str| str.to_sym }).new(*hash.values)You can also use send which prevents the user from setting non-existent instance variables:
def initialize(hash)
hash.each { |key, value| send("#{key}=", value) }
end
Use send when in your class there is a setter like attr_accessor for your instance variables:
class Example
attr_accessor :foo, :baz
def initialize(hash)
hash.each { |key, value| send("#{key}=", value) }
end
end
You make we want to cry :)
In any case, see Object#instance_variable_get and Object#instance_variable_set.
Happy coding.
set_entity callback for all controllers, and I don’t want to interfere with existing instance variables def set_entity(name, model); instance_variable_set(name, model.find_by(params[:id])); end;