Seeking feedback before working on a generator for sqlc

[toniphan21]

Hi everyone,

I am seeking feedback before working on a generator for sqlc. To be clear, there is nothing changed on the sqlc side - it is just a tool to integrate/use sqlc.

Problem

sqlc is a great alternative for ORM. It is an infrastructure layer, but I do not often start with infra - I start with the domain part. Say I have a domain with simple things:

type UserStorer interface {
  CreateUser(ctx context.Context, input CreateUserInput) (User, error)
  
  GetUserByEmail(ctx context.Context, email string) (*User, error)
  
  GetUserByID(ctx context.Context, id string) (*User, error)
}

type User struct {
  ID       string
  Email    string
  Password string
}

Then I work with the storer and entity. After finishing the domain logic, I start to think about infra. At this point I use sqlc like this:

/infra
  - sqlc.yml
  - user.sql -> write sql for CreateUser, GetUserByEmail, GetUserByID...

and the sqlc emitted code looks like this:

// models.go
type User struct {
  // ...
}

// user.sql.go
type CreateUserParams {
  // ...
}

func (q *Queries) CreateUser(ctx context.Context, arg CreateUserParams) (User, error) {...}

func (q *Queries) GetUserByEmail(ctx context.Context, email string) (User, error) {...}

func (q *Queries) GetUserByID(ctx context.Context, id string) (User, error) {...}

Then the next step is to implement UserStorer, which contains a lot of mapping:

• CreateUserInput → CreateUserParams
• model.User → domain.User

I find that there is a lot of space that could be automated:

• I could generate a "standard" sqlc yaml config with sql files based on the interface signature. The purpose is not to automatically change sql in user.sql based on the signature, but to generate boilerplate sql that I could manually edit if needed.
• I could read the domain entity and the output of sqlc to generate the mapper automatically.
• I could read the interface and use the mapper to generate an implementation automatically.

I am also having a mapping solution (go-mapper-gen) but it is currently in a heavy rewrite to align with my other tools.

What I think I need to build

• go-sqlc-gen: a generator that generates boilerplate for sqlc config and mapping configuration.
• go-mapper-gen: a generator that reads the mapping configuration and the sqlc emitted code, then generates the entity mapper and storer implementation.

So if everything works as expected, the workflow will look like this:

• Work on the domain.
• Use go-sqlc-gen to generate standard boilerplate for sqlc.
• Verify and change sqlc.yaml and .sql.
• Run sqlc and go-mapper-gen to generate the implementation from the domain. Ideally, both tools run seamlessly in a single step.

Green components are written or edited by you. Gray components are generated code. Blue components are the tools. Red is `sqlc` itself.

Before I start building, I'd love to hear from anyone who has used sqlc more deeply than I have:

1. Does sqlc already solve this? I may have missed a feature or plugin that handles the domain → infra mapping boilerplate I described.
2. If it doesn't - does the proposed workflow make sense to you? Would you actually use it in your projects?
3. Should I build this at all, or is the problem not worth the tooling overhead?

Thank you for reading and for any feedback you can share!