walterwanderley/sqlc-grpc is a very interesting project that builds on the output of kyleconroy/sqlc to generate a functional REST/JSON and GRPC server. When I started toying with it, I was a little disappointed that I couldn’t easily add any application logic outside of my SQL. This could be great for scaffolding a project, but then it seemed like I might not be able to add anything like validation.
Having had some more time to explore the project, now, I see that there is some
way to be able to add a layer between the communication layer and the database
layer. The key is to add an extra agrument to your sqlc configuration file:
emit_interface.
version: "1"
packages:
- path: "internal/authors"
queries: "./sql/queries.sql"
schema: "./sql/migrations/"
engine: "sqlite"
emit_interface: true
When you generate code with sqlc-grpc with this argument, the authors package
now gets a new file querier.go, which contains the interface representing the
queries that kyleconroy/sqlc generated. The package’s sservice.factory.go
file is an editable file. What this enables for us is to implement the
interface defined in querier.go, which can wrap calls to the Querier
generated by kyleconroy/sqlc, and add application logic.
That’s too many words with maybe not enough structure, so I created a demo repository.