All the examples I've seen so far have a "hardcoded" schema expressed in code. Besides code generation, is there some way to express a schema in another format

All the examples I've seen so far have a "hardcoded" schema expressed in code. Besides code generation, is there some way to express a schema in another format? Is anyone working on a way to define dynamic schemas? For example, a user defined schema rather than a developer defined schema. What I'd really like to see is a tool/library/framework to create a graphQL schema, store it in a database along with the data, and efficiently query the whole assembly. I'm thinking of something like Semantic Mediawiki that isn't terribad. :)