Write to []string from multiple json files using iotil.ReadAll() - json

Question

I have a problem with getting information from json files during reading it from directory. I don't understand, why when i wrote code it's not working at all.
func FilePathWalkDir(root string) ([]string, error) {
var files []string
err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
if !info.IsDir() {
files = append(files, path)
}
return nil
})
return files, err
}
var s []string
func main() {
var (
files []string
err error
)
files, err = FilePathWalkDir("D:/Go/Go_project/Go_pro/files")
if err != nil {
panic(err)
}
for _, file := range files {
//fmt.Println("Index for json:", index)
jsonFile, err := os.Open(file)
if err != nil {
log.Println("Error:", err)
}
defer jsonFile.Close()
byteValue, _ := ioutil.ReadAll(jsonFile)
_ = json.Unmarshal([]byte(byteValue), &s)
log.Printf("Unmarshaled: %v", s)
}
}
After this, i got:
2020/06/21 13:10:03 Unmarshaled: []
2020/06/21 13:10:03 Unmarshaled: []
2020/06/21 13:10:03 Unmarshaled: []
Json files:
First:
{
"name":"Kate",
"date":"2013-04-23T19:24:59.511Z",
"data":"is nice"
}
Second:
{
"name":"Gleison",
"date":"2012-04-23T19:25:00.511Z",
"data":"is a good person"
}
Third:
{
"name":"Rodrigo",
"date":"2013-04-23T20:24:59.511Z",
"data":"is kind"
}

Answer 1

You are trying to unmarshal in slice type []string, while data inside file is map type map[string]string.
Slice type is: ["1", "2", "3"], and Map type is: {"name": "Andrew", "age": 33"}.
Please, read about slices and maps.
func FilePathWalkDir(root string) ([]string, error) {
var files []string
err := filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
if !info.IsDir() {
files = append(files, path)
}
return nil
})
return files, err
}
// var s []string !
var s map[string]string
func main() {
files, err := FilePathWalkDir("D:/Go/Go_project/Go_pro/files")
if err != nil {
panic(err)
}
for _, file := range files {
jsonFile, err := os.Open(file)
if err != nil {
// ???
log.Println("Error:", err)
}
defer jsonFile.Close()
byteValue, _ := ioutil.ReadAll(jsonFile)
if err := json.Unmarshal([]byte(byteValue), &s); err != nil {
// always check errors
panic(err)
}
log.Printf("Unmarshaled: %v", s)
}
}

Answer 2

If you want to convert the map[string] string to the [] string, you can use the following method
var strs []string
strs = append(s[key],strs)
...
But this method will make you lose the map's key.
Why do you use []string instead of map.