config overrides - support additional imports for go generics

[krhubert]

What do you want to change?

Hi,

it would be great to allow add more imports when overriding db types. Let's say we have a Null package like below.

package null

type Null[T any] struct {
  V     T
  Valid bool
}

Now I want to set a custom nullable ts type in config as follows:

  - db_type: "pg_catalog.timestamp"
    nullable: true
    go_type:
      import: "github.com/myproject/null"
      type: "Null[time.Time]"

But this won't import "time" pkg.

Solution

Allow to specify imports instead of import. With this change config will look like:

  - db_type: "pg_catalog.timestamp"
    nullable: true
    go_type:
      imports:
      - "time" 
      - "github.com/myproject/null"
      type: "null.Null[time.Time]"

What database engines need to be changed?

N/A

What programming language backends need to be changed?

Go

[kyleconroy]

I think this is a great idea. When the 1.18 beta was released, I asked for ideas on how sqlc should use them. Allowing people to experiment with nullable wrappers seems like a good first step.

I'm not sold on the config syntax, but I think it's a good starting point.

[krhubert]

  - db_type: "pg_catalog.timestamp"
    nullable: true
    go_type:
      import: "time"\n"github.com/myproject/null"
      type: "null.Null[time.Time]"

There's a great workaround, that worked for me. I only hope it will work in the next versions.

[kyleconroy]

@krhubert Wow, that's one... inventive workaround. It's like SQL injection but for Go code generation.

I think imports vs import works, but need to make sure the code generated constructs the generic type correctly. It sounds like that may already be the case.

[sourcec0de]

Having an imports keys would be awesome. I mentioned a possible API here.

go_type:
  imports: 
    - package: "utils"
      alias: "utils1"
    - package: "data"
      alias: "data1"
  type: "utils1.JSONB[data2.Type]"