JSON / Decoding JSON from a file / Essential Go
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package main
import (
"bytes"
"encoding/json"
"fmt"
"io"
"log"
"os"
)
type Student struct {
Name string
Standard int `json:"Standard"`
}
func decodeFromReader(r io.Reader) ([]*Student, error) {
var res []*Student
dec := json.NewDecoder(r)
err := dec.Decode(&res)
if err != nil {
return nil, err
}
return res, nil
}
func decodeFromString(s string) ([]*Student, error) {
r := bytes.NewBufferString(s)
return decodeFromReader(r)
}
func decodeFromFile(path string) ([]*Student, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
defer f.Close()
return decodeFromReader(f)
}
const jsonStr = `
[
{
"Name" : "John Doe",
"Standard" : 4
},
{
"Name" : "Peter Parker",
"Standard" : 11
},
{
"Name" : "Bilbo Baggins",
"Standard" : 150
}
]
`
func main() {
// studentList, err := decodeFromFile("data.json")
studentList, err := decodeFromString(jsonStr)
if err != nil {
log.Fatalf("decodeFromString() failed with '%s'\n", err)
}
for _, student := range studentList {
fmt.Printf("Student: %s, standard: %d\n", student.Name, student.Standard)
}
}
Go
INFO