How to import local packages in go?

I am new to go and working on an example code that I want to localize.

In the original main.go import statement it was:

 import (
    "log"
    "net/http"
    "github.com/foo/bar/myapp/common"
    "github.com/foo/bar/myapp/routers"
)

Now I have common and routers package in /home/me/go/src/myapp

So I converted the import statement to:

import (
    "log"
    "net/http"
    "./common"
    "./routers"
)

But when I run go install myapp I get these errors:

can't load package: /home/me/go/src/myapp/main.go:7:3: local import "./common" in non-local package

Also, when I use common and routers instead of ./common and ./routers in the import statement, I get:

myapp/main.go:7:3: cannot find package "common" in any of:
    /usr/local/go/src/common (from $GOROOT)
    /home/me/go/src/common (from $GOPATH)
myapp/main.go:8:2: cannot find package "routers" in any of:
    /usr/local/go/src/routers (from $GOROOT)
    /home/me/go/src/routers (from $GOPATH)

How can I fix this?

Well, I figured out the problem. Basically Go starting path for import is $HOME/go/src

So I just needed to add myapp in front of the package names, that is, the import should be:

import (
    "log"
    "net/http"
    "myapp/common"
    "myapp/routers"
)

If you are using Go 1.5 above, you can try to use vendoring feature. It allows you to put your local package under vendor folder and import it with shorter path. In your case, you can put your common and routers folder inside vendor folder so it would be like

myapp/
--vendor/
----common/
----routers/
------middleware/
--main.go

and import it like this

import (
    "common"
    "routers"
    "routers/middleware"
)

This will work because Go will try to lookup your package starting at your project’s vendor directory (if it has at least one .go file) instead of $GOPATH/src.

FYI: You can do more with vendor, because this feature allows you to put "all your dependency’s code" for a package inside your own project's directory so it will be able to always get the same dependencies versions for all builds. It's like npm or pip in python, but you need to manually copy your dependencies to you project, or if you want to make it easy, try to look govendor by Daniel Theophanes

For more learning about this feature, try to look up here

Understanding and Using Vendor Folder by Daniel Theophanes

Understanding Go Dependency Management by Lucas Fernandes da Costa

I hope you or someone else find it helpfully

You should have created your package with go mod init e.g. go mod init github.com/my-org/my-package

Now in my-package you have a sub module called utils for example.

main.go
utils
 |- randstr.go

And your randstr.go looks like this:

package utils

func RandStr(n int) string {
    // TODO: Generate random string....
    return "I am a random string"
}

And then anywhere in your app you would use exported functions from the utils package like this, for example in main.go:

package main

import (
    "fmt"

    // "github.com/my-org/my-package" is the module name at the
    // top of your `go.mod`
    "github.com/my-org/my-package/utils"
)

func main() {
    fmt.Printf("Random string: %s\n", utils.RandStr(20))
}

Import paths are relative to your $GOPATH and $GOROOT environment variables. For example, with the following $GOPATH:

GOPATH=/home/me/go

Packages located in /home/me/go/src/lib/common and /home/me/go/src/lib/routers are imported respectively as:

import (
    "lib/common"
    "lib/routers"
)

Local package is a annoying problem in go.

For some projects in our company we decide not use sub packages at all.

$ glide install
$ go get
$ go install

All work.

For some projects we use sub packages, and import local packages with full path:

import "xxxx.gitlab.xx/xxgroup/xxproject/xxsubpackage

But if we fork this project, then the subpackages still refer the original one.

How to import local packages in go?

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