Using go module 101, undefined types

[Tong Sun]

This is really a go module 101 question, as I'm trying to understand and solve the undefined types problem that I'm having.

I have:

$ head -1 go.mod

module backend

And in my internal/petstore/main.go file, I have:

package main

import api "backend/internal/petstore/interfaces/ports"

func main() {

petStore := api.NewPetStore()

}

And in my internal/petstore/interfaces/ports/type.go file, I have:

package api

type PetStore struct {...}

I think it should compile, but I'm getting:

$ go run internal/petstore/main.go

# command-line-arguments

internal/petstore/main.go:..:38: undefined: api.PetStore

and I have no idea how to fix it.

I also tried to build the whole project with `go build .`, but got

no Go files in <my project root folder>

Please help. thx.

[Axel Wagner]

The code you posted does not actually contain the string `api.PetStore`, so it seems to be incomplete. From extrapolation, I agree that it should work, so the issue must be in that incomplete part.

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[Brian Candler]

> I also tried to build the whole project with `go build .`

To do that you would need:

mkdir -p bin

go build -o bin ./...

The following compiles fine for me. Note that in your original post the error talks about api.PetStore, but the code you showed was a call to api.NewPetStore. Incidentally, you might also want to read https://google.github.io/styleguide/go/best-practices#naming

==> ./go.mod <==
module backend

==> ./internal/petstore/main.go <==

package main

import api "backend/internal/petstore/interfaces/ports"

func main() {

_ = api.PetStore{}
}

==> ./internal/petstore/interfaces/ports/type.go <==