Solve the go project compilation error go mod: no such file or directory

Catalog

The problem background

Solution

In an online environment

Offline environment

---

The problem background

mod Schema project , An error is reported. The third-party database cannot be found go.mod file .

Solution

First of all confirm $GOPATH What is the catalog , For example /a/b, Under normal circumstances, there are src、pkg、bin Three directories , The first two directories must .
mod The dependencies downloaded by the schema project will be placed in /a/b/pkg/mod Next .
（ Compile any mod Project time ）

In an online environment

1, The original go.mod Of documents require Content can copy come out , Then delete the original go.mod and go.sum file （ Rename can also ）,
     If... Is missing before operation go.mod It doesn't matter ;
2, confirm GO111MODULE Whether the switch is on , If not, it needs to be turned on ：

go env -w GO111MODULE=on    or    export GO111MODULE="on"

If you are prompted ：warning: go env -w GO111MODULE=... does not override conflicting OS environment variable
Indicates that the variable has been set in the environment variable , At this point to see /etc/profile file , The end of the file must be the environment variable set before ,
If it is off Will

export GO111MODULE="off"  
 Change it to    
export GO111MODULE="on"

3, Under project directory go mod init, Will produce an empty go.mod file
4, perform go mod tidy Organize dependencies , You can also carry the currently compiled go edition , Such as ：go mod tidy -go=1.16, At this point, we will first finding
     If mod Packages to be downloaded under the directory , Will have a found Words come out ; If not, then download Download the words ;
5, Compile ： If you are prompted no required module provides package ... to add it:   Then the front copy Of mod Paste the content into go.mod In file ：
     fill go.mod There are two ways to file ,linux Next manual require Add in ,goland The next will be automatically filled to mod file ;
     Add go.mod After the document , continue go mod tidy
6, Compile again to succeed

Offline environment

No Faraday fetching dependent packages in offline environment , Therefore, you need to pull down the dependency in the normal compileable environment , Package and transfer to offline environment for compilation .

1, Compile in a normally compileable environment , take mod The directory is compressed ;（ Be sure to make sure the package is complete ）
2, Offline environment , Upload 、 It's decompressed $GOPATH/pkg/mod Under the table of contents , Confirm the offline environment GO111MODULE It's on ;
3, Recompile, . If mod All the packages are complete , Then the compilation is successful , end .
     Otherwise, it will be reported as an error go.mod: no such file or directory, The author's error reporting is the result of this step . Keep looking at the second 4 Step ;
4, If you continue to report this error , The package must be incomplete , Now press the first “ In an online environment ” To deal with , Delete the original go.mod recompile 、 Organize dependencies 、 to mod directories
5, Upload to the offline environment and recompile .

The author has personally waded through the muddy water in both cases , Especially in offline environment, don't be afraid of trouble , After the first compilation, it is packaged and transferred to the offline environment. As a result, the compilation fails ,
The reason is that the package is incomplete , The second compilation found that some packages were downloaded , Therefore, I hope you can solve this problem as soon as possible ！