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This article will explain in detail what GoPath and GoModule are in Golang. The editor thinks it is very practical, so I share it with you for reference. I hope you can get something after reading this article.

GoModule is unable to download foreign dependency packages

In Golang, two concepts are very easy to get wrong, the first is GoPath, the second is GoModule, many beginners do not know the relationship between the two, it is difficult to clearly understand the overall structure of the project, it is difficult to write well-structured code.

What is GoPath?

What is Gopath? In my last blog Golang environment installation & IDEA development Golang, I mentioned the concept of GoPath.

GoPath is the workspace of Golang, and all Go files need to be placed in the src directory under GoPath before they can be compiled and run, so I propose not to configure the global GoPath directory directly, otherwise it will be very difficult to manage all Golang projects.

But in another blog, Golang connects to MySQL database CRUD, I also mentioned that when we use a third-party library in a project, we can use the go get command to directly pull the package of the third-party library from the network, and the pulled package will be downloaded directly to the src package in our GoPath directory.

This leads to a problem that our own Golang code is mixed with third-party Golang files, which is obviously very troublesome for us to manage the Golang project package, and if each project needs the same dependency, then we will download a large number of repeated third-party dependency packages in different GoPath src, which will also take up a lot of disk space.

We set different GoPath for different projects, and the advantages are very obvious:

Easy to manage projects, each project is a different GoPath, which for us to manage multiple Golang projects, can deal with the project structure very clearly. If we put all the projects under the same src package of GoPath, the structure of the project will become very chaotic and difficult to manage.

But when we need to rely on third-party packages, the disadvantages of different GoPath settings for different projects are also obvious:

Third-party dependent packages are mixed with our own Golang packages, which will bring some trouble to our project file management.

Different GoPath needs to download dependencies, so there will be a lot of repeated dependencies on disk, which will take up a lot of disk space.

Therefore, it is a controversial issue whether to set up a GoPath directory to solve the problem of relying on repetition, or to set a different GoPath directory to solve the problem of chaotic structure of Golang projects.

In order to solve all these problems, Golang finally introduced the concept of GoModule.

What is GoModule?

GoModule is a concept initially introduced by Golang in version 1.11 and started in version 1.12, so if you need to use GoModule, you need to make sure that your version of Golang is 1.12 or higher.

Also need to say, although Golang1.11 and version 1.12 have introduced the concept of GoModule, but GoModule is not enabled by default, if you need to open, then you need to configure an environment variable: GO111MODULE=on, default is off.

In Golang1.13 and above, the default configuration of GoModule is auto, that is, GoModule will determine whether to enable GoModule by whether there are go.mod files in your directory. So we don't need to configure the GO111MODULE property in the Golang1.13+ version.

So if you use GoModule, then just use the Golang1.13+ version!

So what exactly is GoModule?

To put it bluntly, GoModule is a workspace for Golang to replace GoPath.

As we said before, all Golang files need to be placed in the GoPath directory to compile and run correctly, and with GoModule, we can put the files in the GoModule directory, and the Golang files placed in the GoModule directory can also be compiled and run correctly.

So after we have GoModule, can GoPath be abandoned?

No!

As we said before, the problems caused by GoPath are caused by the packages of third-party class libraries, so after we have GoModule, GoPath and GoModule are responsible for different responsibilities and work together to serve our Golang project.

GoPath we use to store the third-party dependency packages we pulled from the Internet.

GoModule We use to store our own Golang project files, when our own project needs to rely on third-party packages, we use a go.mod file under the GoModule directory to reference the third-party dependencies under the GoPath directory src package.

This dependency not only solves the problem that programming can only be limited under the GoPath directory src package, but also solves the problem that the third-party dependency package is difficult to manage and repeated dependence takes up disk space.

All in all, after introducing GoModule, instead of programming directly in the GoPath directory, we use GoPath as a repository of third-party dependent packages, and our real workspace is in the GoModule directory.

Settings for GoModule

Now that you've figured out the difference between GoPath and GoModule, how do you configure GoModule? How can a directory be regarded as a GoModule directory?

Quite simply, we can set this directory to the GoModule directory by initializing it directly with the go mod init module name command.

We create a folder under the F:\ GoModule directory named: go_module.

Then enter the directory from the cmd command prompt and execute the go mod init module name initialization command.

After the initialization command is executed, a go.mod file is generated in the go_module directory, which is used to introduce third-party dependent files in the GoPath directory.

Go.mod file after initialization

Module go_module

Go 1.14

When we need to introduce a third-party dependency package under the GoPath directory, just add the dependency name under the go.mod directory, and GoModule will automatically download the third-party dependency package to the GoPath directory for us.

For example, the following go.mod file:

We have introduced two dependencies in this go.mod file, namely, the beego framework v1.12.1 and the mysql driver v1.5.0.

If we use IDE for development, then we can directly create a GoModule project, so that IDE will automatically help us generate the files we need, and when using dependent packages, IDE will automatically help us add dependencies and download dependencies, which will save us a lot of time and can no longer have to remember the specific package name and version number of the dependency.

GoModule is unable to download foreign dependency packages

This is a problem that many developers have encountered. It is obviously very difficult for developers to download foreign dependent packages directly through the network, so Golang also introduces another attribute: GOPROXY. We only need to configure GOPROXY= https://goproxy.io in the environment variables to solve the problem that GoModule cannot download foreign dependent packages.

Of course, it can also be configured through IDE, so that it is difficult to manage too many environment variables in the computer system.

Configure the GOPROXY property in IDEA:

This is the end of the article on "what are GoPath and GoModule in Golang". I hope the above content can be of some help to you, so that you can learn more knowledge. if you think the article is good, please share it for more people to see.

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