Question

I have a MongoMapper model called LogInfo that has a number of fields already defined (:user_id, :user_key, :message, etc)

However, I’d also like the user to embed their own JSON objects as an EmbeddedDocument.

Is there a way to use anonymous objects to create a custom object in MongoMapper? Would I have to resort to the native Ruby driver instead? The final object would look something like this:

{
    user_id: 393,
    user_key: "kdIekHG32Je",
    message: "Application error",
    custom_data: {
        browser: "Firefox 8.0",
        location: {
             lat: 34.323,
             lon: -14.091
        }
    }
}

where the custom_data field is something random the app user can provide.

Answer 1

Sure. You don’t have to resort to the Ruby driver.

MongoMapper turns objects into a MongoDB representation by calling:

ObjectClass.to_mongo(object_instance)

The to_mongo method is already defined for a bunch of standard classes, and you can define it for your own classes too. See lib/mongo_mapper/extensions for all the classes that have to_mongo defined and http://mongomapper.com/documentation/types.html for the documentation on custom types.

BUT, if you’re content to let your users just hand you a hash, it’ll just work.

class LogEntry
  include MongoMapper::Document
  key :custom_data, Hash
end