Ruby: erb throwing error "`result': can't convert String into Integer (TypeError)"

Question

Quick background: I'm setting up a quick and dirty templating scheme where all of my template files are named '*.erb'. the fill in data resides in a yaml file. Output is to files with the name of the template, minus '.erb'.

I haven't done much work with erb, and I'm getting the error "`result': can't convert String into Integer (TypeError)" ... which doesn't make much sense to me.

Here's the class that does the work (generate_interface.rb):

#! /usr/bin/ruby

require 'yaml'
require 'erb'

class GenerateInterface
  def initialize(yamlfile)
    @yamlfile = yamlfile
    @erbfiles = Dir.glob("*.erb")
  end

  def gobutton
    # i -- interface. kept short because it's used all over the place in the erb files.
    i = YAML.load_file( @yamlfile )
    puts( "i: #{i.inspect}" )
    puts( "i['test_id']: #{i['test_id'].inspect}" )
    puts( "( i['test_id'] ).to_s: #{( i['test_id'] ).to_s}" )
    @[email protected] do
      |erbfile|
      puts( "erbfile: #{erbfile.inspect}" )
      outfile = erbfile.gsub(/\.erb$/,"")
      puts( "outfile: #{outfile.inspect}" )
      template = File.open( erbfile, 'r' ) { |f| f.read }
      puts( "template: #{template.inspect}" )
      message = ERB.new(template, "%<>" )
      puts( "message: #{message.inspect}" )
      result=message.result
      puts( "result: #{result.inspect}" )
      File.open(outfile, 'w' ) { |f| f.write( message.result) }
    end
  end

The yaml file (test.yaml):

--- 
test_id: XXX123

The template file (test.txt.erb):

Line 1
Line 2 test_id: <%= i['test_id'] %>
Line 3

The code that drives the whole mess (test.rb):

#! /usr/bin/ruby

require "generate_interface"

test_interface = GenerateInterface.new( "test.yaml" )
test_interface.gobutton

And finally, the output and error messages:

$ ruby -d test.rb
Exception `NoMethodError' at /usr/lib/ruby/1.8/rational.rb:78 - undefined method `gcd' for Rational(1, 2):Rational
i: {"test_id"=>XXX123}
i['test_id']: XXX123
( i['test_id'] ).to_s: XXX123
erbfile: "test.txt.erb"
outfile: "test.txt"
template: "Line 1\nLine 2 test_id: <%= i['test_id'] %>\nLine 3\n"
message: #<ERB:0xb74ac150 @src="_erbout = ''; _erbout.concat \"Line 1\\nLine 2 test_id: \"\n; _erbout.concat(( i['test_id'] ).to_s); _erbout.concat \"\\nLine 3\\n\"\n\n; _erbout", @safe_level="%<>", @filename=nil>
Exception `TypeError' at /usr/lib/ruby/1.8/erb.rb:715 - can't convert String into Integer
/usr/lib/ruby/1.8/erb.rb:715:in `result': can't convert String into Integer (TypeError)
    from /usr/lib/ruby/1.8/erb.rb:714:in `call'
    from /usr/lib/ruby/1.8/erb.rb:714:in `result'
    from ./generate_interface.rb:26:in `gobutton'
    from ./generate_interface.rb:17:in `map'
    from ./generate_interface.rb:17:in `gobutton'
    from test.rb:6

I figured that there was something wrong with _erbout.concat(( i['test_id'] ).to_s), but when I explicitly print ( i['test_id'] ).to_s I get 'XXX123' which is what I expect.

Answer 1

(Your paste of generate_interface.rb missed the final end)

The immediate problem is that the second argument to Erb.initialize is the safe level; the third being the trim options. Your trim options are being interpreted as a safe level.

To fix that, change

  message = ERB.new(template, "%<>" )

to

  message = ERB.new(template, nil, "%<>" )

The second problem is that variable i is not automatically available to your template code. To fix that, you need to pass in a binding, changing

  result = message.result

to

  result = message.result(binding)

In the line following, change message.result to result