@person.foo # method name is foo @person.baaz # method name is baaz I have a need to pass the name of the attribute and not the value of the attribute def process(input) puts input end process(@person.foo) # result should be 'foo' and not the value of foo how do I pass the value 'foo' the attribute name and not the value of attribute to another method. Any help?
on 2007-03-25 12:51
on 2007-03-25 13:35
Perhaps some context would be helpful in this case, but short of that I am assuming you want to invoke the named method later. You can either pass around the symbols as method names (:foo or :baaz in your case) and later use send() e.g class A def hello puts "hello" end end a = A.new a.send :hello # send message to the object or alternatively you can use the Method object like m = a.method(:hello) m.call HTH
on 2007-03-25 19:07
Hi, On 3/25/07, Neeraj K. <firstname.lastname@example.org> wrote: > puts input > end > > > process(@person.foo) # result should be 'foo' and not the value of foo > > how do I pass the value 'foo' the attribute name and not the value of > attribute to another method. > > Any help? Are you looking for something like this? module Kernel private def this_method_name caller =~ /`([^']*)'/ and $1 end end class Foo def bar this_method_name end def baaz this_method_name end end puts Foo.new.bar # => bar puts Foo.new.baaz # => baaz > > HTH, Michael G.
on 2007-03-25 19:17
Sorry I should have been much clearer. The context is that I need the name of the column for the given attribute Person table has name,email and age. class Foo def bar(input) #not sure what goes on here end end Now @user = User.new @foo = Foo.new @foo.bar(@user.age or some form or it) # output shoud the column name 'age' Thanks.
on 2007-03-25 20:09
I do not think you are going to be able to use the API you are thinking about. You are going to have to generate the string before you call the method as in: @foo.bar("user.age") That is why all the association methods take symbols not references. Ruby does not allow you to change the semantics of the calling expression. Michael
on 2007-03-25 21:36
So if I understand you right then you are probably trying to map the value of the column back to the column name. eg.If you have a table like id, name, age 1, "Alice", 25 2, "Bob" , 35 Then given row for id 2, if you have a Fixnum 35 you want to be able to get string "age". Is that right? I am not a Rails expert but you could perhaps use column_names method on AR. your bar could look like def bar(active_record, value) active_record.attribute_names.each do |x| return active_record.column_for_attribute(x).name if active_record[x] == value end end and call it with bar(@user, @user.age) as in your example. There is a big caveat though and that is since we are comparing values there could be more than one column of the same value and this snippet matches the first match. Without going into specifics of what you need you should perhaps look for some alternate approach which could come from your domain use case. - nasir