There is no business logic at all in this tutorial. One example would be she it not even writing resolver on the server level. She is just using basic crud operations. This is one of many tutorial out there and I don't think there is 'de facto' way of using prisma. You can expose your API or you can seperate your API in two parts like they do here
https://www.howtographql.com/graphql-js/4-adding-a-database/
I actually enjoyed that tutorial that Sara did, one thing she says that Int! in graphql would be string and then she does some parseInt() to converted back to a number.
So this is her state
state = { age: ' ' }
If here initial state was just a number like this
state = { age: 0 }