Christian Surlykke
4/28/2007 9:35:00 AM
Lørdag den 28. April 2007 skrev Bino Oetomo:
> Dear All.
>
> I'm learning to use yaml4r
> A friend of me, give a simple script for starting point, i save it as
> lyaml01
>
> ---------Start lyaml01-----
> Nota = Struct.new(:nomor, :items)
> Item = Struct.new(:description, :quantity, :satuan, :harga_satuan,
>
> :total)
>
> nota1 = Nota.new('nota-123', [])
> nota1.items << Item.new('gula', 2, 'kg', 100, 2*100)
> nota1.items << Item.new('kopi', 3, 'kg', 500, 3*500)
>
> # convert to yaml string
> yaml_str = nota1.to_yaml
>
> puts '--- save to file ---'
> open("/mnt/ramdisk0/yaml_file.yml", "w") do |file|
> file.write(yaml_str)
> puts '--- close the file ---'
> file.close
> end
>
> puts '--- reading yaml from file ---'
> nota = YAML::load(IO.read("/mnt/ramdisk0/yaml_file.yml"))
> puts '---- display it ----'
> puts nota
> puts '--- display part ---'
> puts nota.nomor
>
> ---------Stop Lyaml01 -----
>
> Next, I try to run that script :
>
> ---Start lyaml01 run-----
>
>
> [root@kannel blajarruby]# ruby ./lyaml01
> --- save to file ---
> --- close the file ---
> --- reading yaml from file ---
> ---- display it ----
> #<struct Nota nomor="nota-123", items=[#<struct Item description="gula",
> quantity=2, satuan="kg", harga_satuan=100, total=200>, #<struct Item
> description="kopi", quantity=3, satuan="kg", harga_satuan=500,
> total=1500>]>
> --- display part ---
> nota-123
>
> ---Stop lyaml01 run-----
>
> hmmm look nice
>
> And here is the result file generated by that script :
>
> ----Start /mnt/ramdisk0/yaml_file.yml ----
> [root@kannel blajarruby]# more /mnt/ramdisk0/yaml_file.yml
> --- !ruby/struct:Nota
> nomor: nota-123
> items:
> - !ruby/struct:Item
> description: gula
> quantity: 2
> satuan: kg
> harga_satuan: 100
> total: 200
> - !ruby/struct:Item
> description: kopi
> quantity: 3
> satuan: kg
> harga_satuan: 500
> total: 1500
>
> ----Stop /mnt/ramdisk0/yaml_file.yml ----
>
>
> Next i make a copy , just specific on the "YAML::load" part, to try
> re-read the generated file via IRB :
>
> ----Start load yaml irb ------
>
> [root@kannel blajarruby]# irb
> irb(main):002:0> require 'yaml'
> => true
> irb(main):003:0> nota =
> YAML::load(IO.read("/mnt/ramdisk0/yaml_file.yml"))
> TypeError: invalid subclass
> from /usr/local/lib/ruby/1.8/yaml.rb:133:in `transfer'
> from /usr/local/lib/ruby/1.8/yaml.rb:133:in `node_import'
> from /usr/local/lib/ruby/1.8/yaml.rb:133:in `load'
> from /usr/local/lib/ruby/1.8/yaml.rb:133:in `load'
> from (irb):3
> irb(main):004:0>
>
> ----Stop load yaml irb ------
>
> Look like there is problem on this part.
>
> I tried to write a more simple script (i name it "lyaml02"), that will
> just re read the generated file :
>
> -----Start lyaml02 file---------
> [root@kannel blajarruby]# more lyaml02
> require 'yaml'
> nota = YAML::load(IO.read("/mnt/ramdisk0/yaml_file.yml"))
> ----Start lyaml02 file---------
>
> And try to run lyaml02 script :
>
> -----------Start lyaml02 run --------
> [root@kannel blajarruby]# ruby ./lyaml02
> /usr/local/lib/ruby/1.8/yaml.rb:133:in `transfer': invalid subclass
> (TypeError)
> from /usr/local/lib/ruby/1.8/yaml.rb:133:in `node_import'
> from /usr/local/lib/ruby/1.8/yaml.rb:133:in `load'
> from /usr/local/lib/ruby/1.8/yaml.rb:133:in `load'
> from ./lyaml02:2
>
> -----------Stop lyaml02 run --------
>
> question :
> 1. Is it caused by instability of YAML::load ? or
> 2. Could some body point me to something wrong that I did ?
>
> regards
> -bino-
Hi
I'm not an expert on YAML, but I think YAML has to know about the classes Nota
and Item, if it is to load instances of them.
In other words: You should do something like:
require 'yaml'
Nota = Struct.new(:nomor, :items)
Item = Struct.new(:description, :quantity, :satuan, :harga_satuan)
nota1 = YAML::load(File.open('/mnt/ramdisk0/yaml_file.yml'))
puts nota1.inspect
when loading the yaml file.
br. Christian Surlykke