如何在运行时生成graphql模式？

Question

I have a graphql server written in golang using graphql-go api which fetches data from MongoDb and sends the data to the user. But this is when the graphql schema is static. In the future if there is a new field added to a mongodb collection, and the user queries it, then graphql server should be able to fetch that field dynamically. That means, run time schema needs to be generated. The type of the field is unknown. How can this be achieved ?