there are online documents of heroku on how to access config var value from code, and several code samples without D. link here: https://devcenter.heroku.com/articles/config-vars#accessing-config-var-values-from-code.
i have code here: auto uri = environment.get("MONGODB_URI"); MongoClient conn = connectMongoDB(uri); MongoDatabase eqpdb = conn.getDatabase("MbEqpHeroku");
the "MONGODB_URI" showed above already put into heroku's app config as the 'key' and there is a paired 'value'. so the uri is to extract the value which is to use for app to establish mongodb connection.
and above code with error msg here: Error:
getenv cannot be interpreted at compile time, because it has no available source code
so don't know how to make change. thanks in advance!