Using MongoDB in your Silex Project is quite easy.
I will show this with my Superleansilexplate and will integrate it there as an example.
Since i dont want to integrate MongoDB in Superleansilexplate it will just become an additional gist.
Given you have some smaller amount of data like a counter that needs to be stored or other loose coupled datasets, we simply speak to MongoDB “directly” and store the data via Doctrine MongoDB Abstraction Layer.
Since i presume the Data / Document Structure isnt that complex we dont use Doctrine MongoDB ODM (the Object Document Mapper).
If you want to use it instead, try this Silex Extensions.