How to compare keys in yaml files?

Question

There are two ruby on rails internationalization yaml files. One file is complete and another one is with missing keys. How can I compare two yaml files and see missing keys in second file? Are there any tools for doing that?

Answer 1

Assuming file1 is the proper version and file2 is the version with missing keys:

def compare_yaml_hash(cf1, cf2, context = [])
  cf1.each do |key, value|

    unless cf2.key?(key)
      puts "Missing key : #{key} in path #{context.join(".")}" 
      next
    end

    value2 = cf2[key]
    if (value.class != value2.class)
      puts "Key value type mismatch : #{key} in path #{context.join(".")}" 
      next
    end

    if value.is_a?(Hash)
      compare_yaml_hash(value, value2, (context + [key]))  
      next
    end
      
    if (value != value2)
      puts "Key value mismatch : #{key} in path #{context.join(".")}" 
    end    
  end
end

Now

compare_yaml_hash(YAML.load_file("file1"), YAML.load_file("file2"))

Limitation: Current implementation should be extended to support arrays if your YAML file contains arrays.

Answer 2

I couldn't find a fast tool to do that. I decided to write my own tool for this.

You can install it with cabal:

$ cabal update
$ cabal install yamlkeysdiff

Then you can diff two files this way:

$ yamlkeysdiff file1.yml file2.yml
> missing key in file2
< missing key in file1

You can also compare two subsets of the files:

$ yamlkeysdiff "file1.yml#key:subkey" "file2.yml#otherkey"

It behaves exactly like diff, you can do this:

$ yamlkeysdiff file1.yml file2.yml && echo Is the same || echo Is different