I am trying to get a function from the package ModelT into my Controllers package . I have looked at the example on Call a function from another package in Go however it is not working. This is my simple code
package ModelT
-- Print.go
func PrintMe() string {
return "hello"
}
package Controllers
-- Circle.go
import ("Yislyapp/ModelT") -- This does not work
func Circle_List() {
ModelT.PrintMe()
}
My small program won't compile either saying: can not resolve directory yislyapp . I get the samething even if I change it to Yisly-Backend/ModelT or Yisly-Backend./ModelT , it seems like it can't find the package. Any suggestions would be great since i'm starting out. If I put it into my Go file Home.go then it works
import (
"./ModelT"
)
func main() {
ModelT.PrintMe() -- This works in my Home.go file
}
You should set the GOPATH environment variable to the root of your Go project. Your source code should then be somewhere under $GOPATH/src. The import path for a package is the path to the package's directory relative to $GOPATH/src. See https://golang.org/doc/code.html for more info.
Related
I have following folder structure here
server
-main.go
-cmd
-config
-config.go
-handlerr.go
-handlers
-handlers.go
-pkg
-models
-models.go
-db
-db.go
-router
-router.go
and when I am trying to import the "models package" into db package it says "invalid import path:...",this structure i am following with book ,so what am i doing wrong ?How do i import the models into db functions or should i replace them (db and models),any suggest?
enter image description here
Here are the files in the question filled out. The import from db to models is illustrated. I set the module name to "my.example". Change that name to meet your needs. It's best to pick something including a "." to avoid conflict with a standard package. You can run this code on the Go PlayGround. How to Write Go Code explains all of this stuff in detail.
-- main.go --
package main
import (
"my.example/pkg/models/db"
)
func main() {
db.Hello()
}
-- go.mod --
module my.example
-- cmd/config/config.go --
package config
-- cmd/config/handlerr.go --
package config
-- handlers/handlers.go --
package handlers
-- pkg/models/models.go --
package models
func Hello() string { return "hello from models" }
-- pkg/models/db/db.go --
package db
import (
"fmt"
"my.example/pkg/models"
)
func Hello() {
fmt.Println("hello from db and", models.Hello())
}
-- pkg/router/router.go --
package router
Regarding the layout of the files: This is in the land of opinions, so I will just ask you a question. Does the extra level of nesting in the pkg and cmd gain you anything?
UPDATE:
As #maxm reminded me, use GOPATH, here is a great example, that he mentioned.
So, if my web search and a little example program are correct, this is pretty much what is happening here.
Golang sees local packages as folders with .go files, on practice /modules/module.go if modules.go has package modules on the 1st line.
So, when we are including a local package, we are actually including a folder. I created a little example:
/project
main.go
/modules
modules.go
/printer
printer.go
main.go
package main
import (
"./modules/printer"
)
func main() {
printer.Print()
}
modules/modules.go
package modules
import (
"fmt"
)
func Modules() {
fmt.Println("Modules Package")
}
modules/printer/printer.go
package printer
import (
"../../modules"
)
func Print() {
modules.Modules()
}
And this actually works! So, you can import a parent module, you just need to include the folder.
Of course, we cannot have import cycle, Golang won't allow it and if you are having this kind of error, it's better to change the structure of your program.
I'm not talking about paths and stuff, it's just a practical solution. So, smart people, please correct me!
I'm new with Go and I'm trying to build an API, but I'm having some problems at importing functions located at another local package.
My folder structure looks like the following:
├── app.go //at package "main"
└── middleware
├── authentication.go // package "middleware"
I'm trying to import the functions inside the authentication.go file like that:
package main
import (
"fmt"
"log"
"net/http"
"./middleware" //Also tried "middleware"
)
Thinking that's an import problem because if I move the functions to the same package and folder, it works fine.
The func I'm trying to use also starts with caps, so there shouldn't be a problem importing it:
func AuthMiddleware(next http.Handler) http.Handler {
//...
}
What's wrong with my code? Also, what's the best way to import a local package without having to write the whole path?
I'm using Go 1.15.2, and checked all related S.O posts, but none looks to solve my problem.
EDIT :
Whenever you use a function located at another package, you have to refer first to the package. I was trying to call my function as AuthMiddleware(parameters) but the right way to call it was middleware.AuthMiddleware(parameters).
Don't use dot import paths like this, it is not recommended. Use the relative path for your go src dir (which can be local only, it doesn't have to be online) and it'll work fine.
So something like
import "me.com/api/middleware"
Then to avoid stutter perhaps:
middleware.Auth()
There is two way to call function from another package
You can use package or alias to call function
With package name
package main
import (
"./middleware"
)
middleware.Auth();
With alias
package main
import (
mid "./middleware"
)
mid.Auth();
You can import whole package by using . , after that you do not need to use alias or package name to call function. You can use call function directly with function name
package main
import (
. "./middleware"
)
Auth();
I'm trying to import a subdirectory I have in my project to my main file, but for some reason I get this error:
could not import ./service (no package for import ./service)
This is how I import:
import (
"os"
"service"
)
I also tried "service/app"
"./service/app"
"./service" nothing works, always the same error.
I'm trying to use the app.go file
This is the file structure:
Project Directory
-- main.go
-- service (directory)
-- app.go (file)
I tried to restart VS Code, tried to use go install/update tools, nothing works.
Also, this is my main func:
func main() {
a := &service.App()
a.Initialize(
os.Getenv("APP_DB_USERNAME"),
os.Getenv("APP_DB_PASSWORD"),
os.Getenv("APP_DB_NAME"),
)
a.Run(":8010")
}
&service.App() does not show a problem, but when I remove the "service" import, it does say
undeclared name: service
So I don't understand what the problem is.
This error sometime show on the "os" import too, I don't know why.
Golang doesn't support relative imports.
In modules, there finally is a name for the subdirectory. If the parent directory says "module m" then the subdirectory is imported as "m/subdir", no longer "./subdir".
So, in your case you should import service package as your_module_name/service.
Intro
I'm trying to import my EventController.go to my main.go file.
Directory:
├───Controllers
│ └───Event
│ └───EventController.go
├───Models
├───Routes
│
└ Main.go
Problem:
import (
"log"
"net/http"
_ "/Controllers/Event/EventController.go" //problem here
)
error : cannot import absolute path
I read some documentation but the thing is I see that I'm doing it correctly, though i learnt about $GOPATH but I want to use the local directory thing.
What am I doing wrong and what's this error about
NOTE: I want add that I'm using windows as os
Thank you.
There are a few issues:
Packages are imported, not files (as noted in other answers)
File absolute import paths are not valid as the error states. An application can use file relative import paths (the path starts with "./") or a path relative to the Go workspace. See the go command doc for info on the syntax. Import paths relative to the Go workspace are the preferred form.
It is idiomatic to use lowercase names for packages (and their corresponding directories). The camel case names in the question are workable, but it's better to go with the flow.
The document How to Write Go Code is a nice tutorial on how to do this.
Here's how to reorganize the code given the above. This assumes that main.go is in a package with import path "myapp". Change this import path to whatever you want.
-- main.go --
package main
import (
"log"
_ "myapp/controllers/event"
)
func main() {
log.Println("hello from main")
}
-- go.mod --
module myapp
-- controllers/event/eventController.go --
package event
import "log"
func init() {
log.Println("hello from controllers/event")
}
Run this example on the Go playground.
You cannot import a file. You can import a package. So, lets say your main is the package "github.com/mypackage", then you should import "github.com/mypackage/Controllers/Event".
Go supports package level import. You can import a package by adding it to the import statement at the beginning of the file.
In your case, you should do something like this-
import (
"log"
"net/http"
"Controllers/Event/EventController"
)
Also, you should remove first "/" from the file name
_ /Controllers/Event/EventController.go" //problem here
because your Controllers folder is at the same level as Main.go file. You should always give relative path in the import statements.
In this way, you can use any file which is listed under EventController folder.
With halfdans advice, I was successfully able to use goinstall github.com/hoisie/web.go without any errors after installing git first. However, now when I try to compile the sample code given, go is not finding the web package. I get the error,
main.go:4: can't find import: web
On this code
package main
import (
"web"
)
func hello(val string) string { return "hello " + val }
func main() {
web.Get("/(.*)", hello)
web.Run("0.0.0.0:9999")
}
Is there something special I need to do in order for it to recognize the package? I found the package source at $GOROOT/src/pkg/github.com/hoisie/web.go/web. I tried github.com/hoisie/web.go/web as the import and it still did not like that.
If you install web.go through goinstall, you need to do:
import "github.com/hoisie/web.go"
Goinstall is still an experimental system. It would be nice if you didn't have to include the full path.
import web "github.com/hoisie/web.go"