Learn X By Example
Learn X By Example

    Go by Example: Embed Directive

    Go by Example : Embed Directive

    //go:embed is a compiler directive that allows programs to include arbitrary files and folders in the Go binary at build time. Read more about the embed directive here .

    package main

    Import the embed package; if you don’t use any exported identifiers from this package, you can do a blank import with _ "embed" .

    import (
    "embed"
)

    embed directives accept paths relative to the directory containing the Go source file. This directive embeds the contents of the file into the string variable immediately following it.

    //go:embed folder/single_file.txt
var fileString string

    Or embed the contents of the file into a []byte .

    //go:embed folder/single_file.txt
var fileByte []byte

    We can also embed multiple files or even folders with wildcards. This uses a variable of the embed.FS type , which implements a simple virtual file system.

    //go:embed folder/single_file.txt
//go:embed folder/*.hash
var folder embed.FS
    func main() {

    Print out the contents of single_file.txt .

        print(fileString)
    print(string(fileByte))

    Retrieve some files from the embedded folder.

        content1, _ := folder.ReadFile("folder/file1.hash")
    print(string(content1))
        content2, _ := folder.ReadFile("folder/file2.hash")
    print(string(content2))
}

    Use these commands to run the example. (Note: due to limitation on go playground, this example can only be run on your local machine.)

    $ mkdir -p folder
$ echo "hello go" > folder/single_file.txt
$ echo "123" > folder/file1.hash
$ echo "456" > folder/file2.hash
    $ go run embed-directive.go
hello go
hello go
123
456

    Next example: Testing and Benchmarking .

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