无法使用viper进行解组

Question

我一直试图通过对JSON文件进行解组来提取一些JSON，但我不知道为什么没有这样做。我可以使用viper.AllSettings()获取数据，但不能通过解组获取。我认为我犯了一个愚蠢的错误，请分享你的想法。github链接是-https://github.com/parthw/100-days-of-code/tree/main/golang/d6-cobra-viper-continued代码如下。

main.go

package main
import (
"fmt"
"example.com/cobra-viper/cmd"
"github.com/spf13/viper"
)
// Myconfig example
type Myconfig struct {
username string `mapstructure:"username"`
}
func main() {
cmd.Execute()
fmt.Println("I can print this ", viper.AllSettings())
var mc Myconfig
if err := viper.Unmarshal(&mc); err != nil {
fmt.Println(err)
}
fmt.Println(mc)
}

使用cmd目录中的cobra CLI生成的代码：

package cmd
import (
"fmt"
"os"
"github.com/spf13/cobra"
homedir "github.com/mitchellh/go-homedir"
"github.com/spf13/viper"
)
var (
cfgFile string
author  string
)
// Myconfig example
type Myconfig struct {
username string
}
// rootCmd represents the base command when called without any subcommands
var rootCmd = &cobra.Command{
Use:   "cobra-viper",
Short: "A brief description of your application",
Long: `A longer description that spans multiple lines and likely contains
examples and usage of using your application. For example:
Cobra is a CLI library for Go that empowers applications.
This application is a tool to generate the needed files
to quickly create a Cobra application.`,
// Uncomment the following line if your bare application
// has an action associated with it:
Run: func(cmd *cobra.Command, args []string) {
fmt.Println("Welcome to rootcmd")
var mc Myconfig
if err := viper.Unmarshal(&mc); err != nil {
fmt.Println(err)
}
fmt.Println(mc)
fmt.Println("I can print this ", viper.AllSettings())
},
}
// Execute adds all child commands to the root command and sets flags appropriately.
// This is called by main.main(). It only needs to happen once to the rootCmd.
func Execute() {
if err := rootCmd.Execute(); err != nil {
fmt.Println(err)
os.Exit(1)
}
fmt.Println("I can print this ", viper.AllSettings())
}
func init() {
cobra.OnInitialize(initConfig)
// Here you will define your flags and configuration settings.
// Cobra supports persistent flags, which, if defined here,
// will be global for your application.
rootCmd.PersistentFlags().StringVar(&cfgFile, "config", "", "config file (default is $HOME/.cobra-viper.json)")
//rootCmd.PersistentFlags().StringVar(&author, "author", "YOUR NAME", "Author name for copyright attribution")
// Cobra also supports local flags, which will only run
// when this action is called directly.
//rootCmd.Flags().BoolP("toggle", "t", false, "Help message for toggle")
//viper.BindPFlag("author", rootCmd.PersistentFlags().Lookup("author"))
}
// initConfig reads in config file and ENV variables if set.
func initConfig() {
if cfgFile != "" {
// Use config file from the flag.
viper.SetConfigFile(cfgFile)
} else {
// Find home directory.
home, err := homedir.Dir()
if err != nil {
fmt.Println(err)
os.Exit(1)
}
// Search config in home directory with name ".cobra-viper" (without extension).
viper.AddConfigPath(home)
viper.SetConfigName(".cobra-viper")
}
viper.AutomaticEnv() // read in environment variables that match
// If a config file is found, read it in.
if err := viper.ReadInConfig(); err == nil {
fmt.Println("Using config file:", viper.ConfigFileUsed())
}
}

输出：

~/Documents/personal-git/100-days-of-code/golang/d6-cobra-viper-continued(main*) » go run main.go                                                                                   
Using config file: /Users/parth/.cobra-viper.json
Welcome to rootcmd
{}
I can print this  map[username:parth-wadhwa]
I can print this  map[username:parth-wadhwa]
I can print this  map[username:parth-wadhwa]
{}

JSON文件：

~/Documents/personal-git/100-days-of-code/golang/d6-cobra-viper-continued(main*) » cat /Users/parth/.cobra-viper.json                                                              
{
"username": "parth-wadhwa"
}

Answer 1

如果MyConfig结构中的username字段是否导出，那么问题就简单地归结为一个事实。它需要大写为"；导出"；以便CCD_ 4将该值解码到结构中。

type Myconfig struct {
Username string `mapstructure:"username"`
}

您可以查看JSON和处理未导出字段，以了解json包需要它的更多原因。