Golang：类型[type]不是表达式； json配置解析

Question

I'm trying to work out a bit of code to pull in config from a JSON file. When I attempt to build, I get this error

type ConfigVars is not an expression

Below is the config and program code I'm trying to work with. Every example I've found so far is similar to the below code. Any suggestion of what I'm doing incorrectly?

-- Config File
{"beaconUrl":"http://test.com/?id=1"}

-- Program Code
package main

import (
    "encoding/json"
    "fmt"
    "os"
)


type ConfigVars struct {
    BeaconUrl   string
}


func main() {
    configFile, err := os.Open("config.json")
    defer configFile.Close()
    if err != nil {
        fmt.Println("Opening config file", err.Error())
    }

    jsonParser := json.NewDecoder(configFile)
    if err = jsonParser.Decode(&ConfigVars); err != nil {
        fmt.Println("Parsing config file", err.Error())
    }
}

Answer 1

What you're doing there is trying to pass a pointer to the ConfigVars type (which obviously doesn't really mean anything). What you want to do is make a variable whose type is ConfigVars and pass a pointer to that instead:

var cfg ConfigVars
err = jsonParser.Decode(&cfg)
...