0pen a file

Use the os-Package and not the io/ioutil because since the go version 1.16 all the functions are also on the os-Package.

import "os"

var filename string = "./file.txt"
file, err := os.ReadFile(filename)
if err != nil {
	fmt.Println("can not get file with name: " + filename)
	return
}

Get from JSON-File

Read from a file

fileContent := ""
	file, err := os.Open("file.txt")
	if err != nil {
		fileContent = fmt.Sprintf("error during to open the file 'file.txt' -> %s", err.Error())
	}
	defer file.Close()

	content, err := io.ReadAll(file)
	if err != nil {
		fileContent = fmt.Sprintf("error during to open the file 'file.txt'")
	}

	fileContent = string(content)