Ruby：将新字段添加到YAML文件

Question

I've been searching around for a bit and couldn't find anything that really helped me. Especially because sometimes things don't seem to be consistant.

I have the following YAML that I use to store data/ configuration stuff:

---
global:
  name: Core Config
  cfg_version: 0.0.1
  databases:
    main_database:
      name: Main
      path: ~/Documents/main.reevault
      read_only: false    

    ...

I know how to update fields with:

cfg = YAML.load_file("test.yml")
cfg['global']['name'] = 'New Name'
File.open("test.yml", "w"){ |f| YAML.dump(cfg, f) }

And that's essentially everybody on the internet talks about. However here is my problem: I want to dynamically be able to add new fields to that file. eg under the "databases" section have a "secondary_db" field with it's own name, path and read_only boolean. I would have expected to do that by just adding stuff to the hash:

cfg['global']['databases']['second_db'] = nil
cfg['global']['databases']['second_db']['name'] = "Secondary Database"
cfg['global']['databases']['second_db']['path'] = "http://someurl.remote/blob/db.reevault"
cfg['global']['databases']['second_db']['read_only'] = "true"
File.open("test.yml", "w"){ |f| YAML.dump(cfg, f) }

But I get this error:

`<main>': undefined method `[]=' for nil:NilClass (NoMethodError)

My question now is: how do I do this? Is there a way with the YAML interface? Or do I have to write stuff into the file manually? I would prefer something via the YAML module as it takes care of formatting/ indentation for me.

Hope someone can help me.

Answer 1

Yo have to initialize cfg['global']['database']['second_db'] to be a hash not nil. Try this cfg['global']['database']['second_db'] = {}