Could not import local modules in Golang - go

Question

I am trying to import local modules, but I am unable to import it using go mod. I initially built my project using go mod int github.com/AP/Ch2-GOMS
Note my environment is go1.14 and I am using VSCode as my editor.
This is my folder structure
Ch2-GOMS
│ ├── go.mod
│ ├── handlers
│ │ └── hello.go
│ └── main.go
My main.go code:
package main
import (
"log"
"net/http"
"os"
"github.com/AP/Ch2-GOMS/handlers" // This gives "could not import github.com/AP/Ch2-GOMS/handlers" lint error
)
func main() {
l := log.New(os.Stdout, "product-api", log.LstdFlags)
hh := handlers.NewHello(l)
sm := http.NewServeMux()
sm.Handle("/", hh)
http.ListenAndServe(":9090", nil)
}
I cannot see auto-complete for my local modules such as handlers.NewHello.
go build generated go.mod contents:
module github.com/AP/Ch2-GOMS
go 1.14
I am also getting You are neither in a module nor in your GOPATH. Please see https://github.com/golang/go/wiki/Modules for information on how to set up your Go project. warning in VScode, even though i have set GO111MODULE=on in my ~/.bashrc file

Answer 1

Read: Ian Lance Taylor's comment (Go's Core Team)
I know of three ways:
Method 1 (The best way):
# Inside
# Ch2-GOMS
# │ ├── go.mod
# │ ├── handlers
# │ │ └── hello.go
# │ └── main.go
# In Ch2-GOMS
go mod init github.com/AP/Ch2-GOMS
# In main.go
# Add import "github.com/AP/Ch2-GOMS/handlers"
# But, make sure:
# handlers/hello.go has a package name "package handlers"
You must be doing something wrong and that's why it's not working.
Method 2 (The good way):
# Inside
# Ch2-GOMS
# │ ├── go.mod
# │ ├── handlers
# │ │ └── hello.go
# │ └── main.go
# Inside the handlers package
cd Ch2-GOMS/handlers
go mod init github.com/AP/Ch2-GOMS/handlers # Generates go.mod
go build # Updates go.mod and go.sum
# Change directory to top-level (Ch2-GOMS)
cd ..
go mod init github.com/AP/Ch2-GOMS # Skip if already done
go build # Must fail for github.com/AP/Ch2-GOMS/handlers
vi go.mod
Inside Ch2-GOMS/go.mod and add the following line:
# Open go.mod for editing and add the below line at the bottom (Not inside require)
replace github.com/AP/Ch2-GOMS/handlers => ./handlers
# replace asks to replace the mentioned package with the path that you mentioned
# so it won't further look packages elsewhere and would look inside that's handlers package located there itself
Method 3 (The very quick hack way for the impatient):
Turn off Go Modules GO111MODULE=off
Remove go.mod file
# Check: echo $GOPATH
# If $GOPATH is set
mkdir -p $GOPATH/src/github.com/AP/Ch2-GOMS
cd $GOPATH/src/github.com/AP/Ch2-GOMS
# If $GOPATH is unset
mkdir -p ~/go/src/github.com/AP/Ch2-GOMS
cd ~/go/src/github.com/AP/Ch2-GOMS
# Now create a symbolic link
ln -s <full path to your package> handlers
Reason: During the build, the compiler first looks in vendor, then GOPATH, then GOROOT. So, due to the symlink, VSCode's go related tools will also work correctly due to the symlink provided as it relies on GOPATH (They don't work outside of GOPATH)

Answer 2

Below are the steps-
on main folder - go mod init
2.go mod tidy
3.go to the folder where main file is present
4.install the package via
go get <package name>
5.go build
Before above steps your project path should be
project path = GOPATH/src/<project_name>
Along with there should be 2 more folder parallel with src folder
src
pkg
bin
when ever you install any package it should be go inside pkg folder
and after doing go mod tidy there should be one file generated
go.mod
List item

Answer 3

go mod tidy alone at root folder did it for me

Answer 4

If you want to import local modules, you need to map the module path such that it can find the code in your local file system.
First use the go mod edit command to replace any imports to module to the local file
$ go mod edit -replace example.com/greetings=../greetings
The command specifies that example.com/greetings should be replaced with ../greetings for the purpose of locating the dependency. After you run the command, the go.mod file in the current directory should include a replace directive in its mod file
After that use the go mod tidy command to synchronize dependencies, adding those required by code where you imported but not yet traced by the current module
$ go mod tidy
Referred from the official documentation