When iterating over hash, getting "TypeError: can't convert String into Integer"

Question

I have a hash (the real one is much bigger)

parsed = {"follower_count" => 500, "something_else" => "etc", "xyz" => "abc"}

and a class hanging around that looks like this

 class Company
   attr_accessor :followers

   def initialize(thehash)
      @followers = thehash['follower_count']
   end
 end

So lastly there is this code which throws the error before I can worry about anything else going wrong

>> parsed.map {|t| Company.new(t)}
TypeError: can't convert String into Integer
  from (irb):7:in `[]'
  from (irb):7:in `initialize'
  from (irb):12:in `new'
  from (irb):12
  from (irb):12:in `map'
  from (irb):12:in `each'
  from (irb):12:in `map'
  from (irb):12

mu is too short · Accepted Answer · 2012-07-10 02:58:44Z

3

When you iterate over a Hash, the block gets an array as its argument and that array contains (in order) the key and value for one pair in the Hash. So, in here:

parsed.map { |t| ... }

t is actually a two element array and is usually written:

parsed.map { |k, v| ... }

Then, inside Company#initialize, you're treating t as a Hash when it is actually a two element Array.

You don't want to use map on parsed at all, you just want to Company.new(parsed).

answered Jul 10, 2012 at 2:58

mu is too short

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Ned Batchelder · Accepted Answer · 2012-07-10 02:59:10Z

2

When you use map on a hash, you should use two variables in the block:

parsed.map {|k,v| .. use k and v here .. }

It doesn't seem like you want to iterate over parsed at all, you want to use it as the argument to Company.new:

Company.new(parsed)

answered Jul 10, 2012 at 2:59

Ned Batchelder

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