Go 1.16.4: purpose of go mod tidy

One , view help :

1, View original document

[email protected]:/data/go/mod3$ go help mod tidy
usage: go mod tidy [-e] [-v]

Tidy makes sure go.mod matches the source code in the module.
It adds any missing modules necessary to build the current module's
packages and dependencies, and it removes unused modules that
don't provide any relevant packages. It also adds any missing entries
to go.sum and removes any unnecessary ones.

The -v flag causes tidy to print information about removed modules
to standard error.

The -e flag causes tidy to attempt to proceed despite errors
encountered while loading packages.

See https://golang.org/ref/mod#go-mod-tidy for more about 'go mod tidy'.

2, explain ： You can see go mod tidy Role of command :

Add required but go.mod Modules not found in ,

Delete unused modules

explain ： Liu Hongdi's go The forest is a focus golang The blog of ,
           Address ：https://blog.csdn.net/weixin_43881017

explain ： author : Liu Hongdi mailbox : [email protected]

Two , demonstration ： Delete unused modules

1, see go.mod The content of :

[email protected]:/data/go/mod3$ more go.mod 
module mod3

go 1.16

require github.com/gin-gonic/gin v1.7.2 // indirect

2, install gorm2

[email protected]:/data/go/mod3$ go get -u gorm.io/gorm
go: downloading gorm.io/gorm v1.21.10
go: downloading github.com/jinzhu/inflection v1.0.0
go: downloading github.com/jinzhu/now v1.1.2
go get: added gorm.io/gorm v1.21.10

View again go.mod

[email protected]:/data/go/mod3$ more go.mod 
module mod3

go 1.16

require (
        github.com/gin-gonic/gin v1.7.2 // indirect
        gorm.io/gorm v1.21.10 // indirect
)

You can see gorm Has been added to go.mod

3, perform tidy Check the effect after the command

[email protected]:/data/go/mod3$ go mod tidy
go: downloading github.com/go-playground/assert/v2 v2.0.1
go: downloading gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405

View again go.mod

[email protected]:/data/go/mod3$ more go.mod 
module mod3

go 1.16

require github.com/gin-gonic/gin v1.7.2

You can see that because we haven't used the newly added gorm2,

therefore gorm2 The module is go mod tidy The command removed

3、 ... and , demonstration ： Add used but go.mod Module that does not exist in :

1, Manual from go.mod Delete in gin Module reference

[email protected]:/data/go/mod3$ vi go.mod

Check... When you're done go.mod

[email protected]:/data/go/mod3$ more go.mod
module mod3

go 1.16

2, perform tidy

[email protected]:/data/go/mod3$ go mod tidy
go: finding module for package github.com/gin-gonic/gin
go: found github.com/gin-gonic/gin in github.com/gin-gonic/gin v1.7.2

View again go.mod

[email protected]:/data/go/mod3$ more go.mod
module mod3

go 1.16

require github.com/gin-gonic/gin v1.7.2

Because we used gin modular ,
therefore go mod tidy Automatically for us in go.mod Added what has just been added gin modular

Four , see go Version of :

[email protected]:/data/go/mod3$ go version
go version go1.16.4 linux/amd64