如何在Ruby中转义符号（不是字符串）

Question

I'm creating a web crawler with Ruby and Mechanize. The web site that I'm crawling is sending this kind of POST data with square brackets. The problem is that Mechanize uses struct and I haven't found a way to escape the square brackets in a struct key:

   post_body = {
       data[User][username]: username,
       data[User][password]: password,
       data[selector]: 1
   } 

I've tried to put the keys inside strings, and to use this kind of syntax:

post_body = Struct.new(#{data[User][username]}, #{data[User][password]}, #{data[selector]})
post_body.new(username, password, 1)

but I get an error:

identifier data[User][username] needs to be constant

Answer 1

To make what @ndenkov already said more explicit:

If you have a hash

{ foo: 4711 }

this is just syntactic sugar for

{ :foo => 4711 }

This means that the key must syntactically be a simple symbol, basically following the same syntax as an identifier.