Is there a YAML Database?

Question

I like YAML's data model a lot, preserving most of the simplicity of JSON and extending it with a few sometimes-important features like custom data types and references.

So is there any way to store a lot of data in the YAML data model (or something very similar) and query it using an index? Like a YAML database, analogous to XML databases or JSON databases like Mongo DB. Or is there a mapper from YAML to something like Mongo DB that lets me transparently use it as a YAML store?

I haven't found anything so maybe there aren't any. Why would that be? Is it a stupid idea or is YAML simply too young and they will come?

Answer 1

Or is there a mapper from YAML to something like Mongo DB that lets me transparently use it as a YAML store?

Not directly as far as I know.

The main problem seems to be that Mongo DB's interface is based on a hash (i.e. key-value pairs). So in essence you are asking if there is a mapper from YAML to a hash. The answer is no simply because YAML can store arbitrary structures while hashes cannot.

But if you're willing to simplify your objects, you might be able to partially do this:

class SomeObject   def initialize     @bob = 'abc'     @fred = 'cde'   end    def to_hash     h = {}     instance_variables.sort.each do |v|     h[v] = instance_variable_get(v)   end   return h end 

If you look at the to_yaml code you'll see that it's very similar to the to_hash method (because that's where I got the idea).

Note you'll probably need a from_hash method as well. And you probably want to start working out a scheme for classes with instance variables that are objects (i.e. not just Strings, Symbols, etc.)

Now the mongo code to insert the item:

include Mongo db = MongoClient.new.db('test') stuff = db.collection('stuff') item = SomeClass.new() ... other code ... stuff.insert(item.to_hash) 

I realize this doesn't answer your question directly, but hopefully it still helps.

John