Question

I am trying ‘mongo-ruby-driver’ for some project. It’s working fine except when I call to_json on mongo object. It gives well formed json but it’s not converting BSON::Code into readable value i resulting JSON.

Instead of showing code text, it show something like

#<BSON::Code:0x00000100af6fa8>

Did anyone tried it. Any help id highly appreciated.

UPDATE

here is some code snippet:

@records is variable that contains Array of MongoDB documents in hash.

@records.to_json

When I call to_json on it it gives everything as expected. except for the key that contain BSON::Code (means javascript code). for example consider following doc:

{ 
  "_id" : "contains", 
  "value" : function( obj, target ) { return obj.indexOf(target) != -1; }; 
}

Querying same doc from ruby gives output like:

{
  "_id"=>"contains", 
  "value"=><BSON::Code:2160165280 @data="function( obj, target ) { return obj.indexOf(target) != -1; };" @scope="{}">
}

and calling to_json on this gives following:

{"_id":"contains","value":"#<BSON::Code:0x00000100b54658>"}

this is what the problem is. Instead of getting actual code for ‘value’ key I am getting ruby object as string.

Calling code method on BSON::Code we can get it converted into code. But for that I need to loop mongo docs, check values for each key, calling code on it if it is an object of BSON::Code and then assigning it back to key. And at last we can call to_json on it. But I dont want this much overhead. I need to_json itself should take care of it.

Answer 1

The serializer that is iterating over the attributes of the objects in the array is probably calling the to_s method which would cause the output you are seeing.

You can either monkey patch the BSON::Code class to include a to_s method which calls inspect (the method that produces the output you want) or modify the serializer to detect when it encounters a BSON::Code instance and call inspect on it rather than to_s.

The code to mokey patch the BSON::Code class would look like this:

module BSON
  class Code
    def to_s
      inspect
    end
  end
end

This would have the same behavior as inspect. If you just wanted the code you could monkey patch this in:

module BSON
  class Code
    def to_s
      @code
    end
  end
end

I might make this the default behavior for to_s in the driver but for now just include that in your code and it should work like a champ.