API to get the module name - go

Question

Is there an API to get the module name of a project which uses go 1.11 module system?
so I need to get abc.com/a/m from the module definition module abc.com/a/m in go.mod file.

Answer 1

As of this writing, I am not aware of any exposed APIs for that. However, looking at go mod sources, there is a function that can be quite useful in Go mod source file
// ModulePath returns the module path from the gomod file text.
// If it cannot find a module path, it returns an empty string.
// It is tolerant of unrelated problems in the go.mod file.
func ModulePath(mod []byte) string {
//...
}
func main() {
src := `
module github.com/you/hello
require rsc.io/quote v1.5.2
`
mod := ModulePath([]byte(src))
fmt.Println(mod)
}
Which outputs github.com/you/hello

Answer 2

Try this?
package main
import (
"fmt"
"io/ioutil"
"os"
modfile "golang.org/x/mod/modfile"
)
const (
RED = "\033[91m"
RESET = "\033[0m"
)
func main() {
modName := GetModuleName()
fmt.Fprintf(os.Stdout, "modName=%+v\n", modName)
}
func exitf(beforeExitFunc func(), code int, format string, args ...interface{}) {
beforeExitFunc()
fmt.Fprintf(os.Stderr, RED+format+RESET, args...)
os.Exit(code)
}
func GetModuleName() string {
goModBytes, err := ioutil.ReadFile("go.mod")
if err != nil {
exitf(func() {}, 1, "%+v\n", err)
}
modName := modfile.ModulePath(goModBytes)
fmt.Fprintf(os.Stdout, "modName=%+v\n", modName)
return modName
}

Answer 3

If your starting point is a go.mod file and you are asking how to parse it, I would suggest starting with go mod edit -json, which outputs a particular go.mod file in JSON format. Here is the documentation:
https://golang.org/cmd/go/#hdr-Edit_go_mod_from_tools_or_scripts
Alternatively, you could use rogpeppe/go-internal/modfile, which is a go package that can parse a go.mod file, and which is used by rogpeppe/gohack and some other tools from the broader community.
Issue #28101 I think tracks adding a new API to the Go standard library to parse go.mod files.
Here is a snippet of the documentation for go mod edit -json:
The -json flag prints the final go.mod file in JSON format instead of
writing it back to go.mod. The JSON output corresponds to these Go
types:
type Module struct {
Path string
Version string
}
type GoMod struct {
Module Module
Go string
Require []Require
Exclude []Module
Replace []Replace
}
type Require struct {
Path string
Version string
Indirect bool
}
Here is an example snippet of JSON output from go mod edit -json that shows the actual module path (aka module name), which was your original question:
{
"Module": {
"Path": "rsc.io/quote"
},
In this case, the module name is rsc.io/quote.

Answer 4

As of Go 1.12 (for those finding this via a search who are using modules but not necessarily the older version the OP mentioned), the runtime/debug package includes functionality for getting information about the build, including the module name. For example:
import (
"fmt"
"runtime/debug"
)
func main() {
info, _ := debug.ReadBuildInfo()
fmt.Printf("info: %+v", info.Main.Path)
}
You can run this example on the playground: https://go.dev/play/p/5oGbCRxSnjM
For more information, see the documentation for "runtime/debug".BuildInfo