이 름 : 바다아이
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짧은 주소 : https://www.bada-ie.com/su/?701591779510
구조체에 json 을 사용할 수 있습니다.
구조체 정의하면서 옆에
`json:"page"``json:"fruits"`
이렇게 붙는 것이 요게 핵심입니다.
아래는 예제입니다.
// Go offers built-in support for JSON encoding and// decoding, including to and from built-in and custom// data types.package main
import"encoding/json"import"fmt"import"os"// We'll use these two structs to demonstrate encoding and// decoding of custom types below.type response1 struct {
Page int
Fruits []string
}
type response2 struct {
Page int`json:"page"`
Fruits []string`json:"fruits"`
}
funcmain() {
// First we'll look at encoding basic data types to// JSON strings. Here are some examples for atomic// values.
bolB, _ := json.Marshal(true)
fmt.Println(string(bolB))
intB, _ := json.Marshal(1)
fmt.Println(string(intB))
fltB, _ := json.Marshal(2.34)
fmt.Println(string(fltB))
strB, _ := json.Marshal("gopher")
fmt.Println(string(strB))
// And here are some for slices and maps, which encode// to JSON arrays and objects as you'd expect.
slcD := []string{"apple", "peach", "pear"}
slcB, _ := json.Marshal(slcD)
fmt.Println(string(slcB))
mapD := map[string]int{"apple": 5, "lettuce": 7}
mapB, _ := json.Marshal(mapD)
fmt.Println(string(mapB))
// The JSON package can automatically encode your// custom data types. It will only include exported// fields in the encoded output and will by default// use those names as the JSON keys.
res1D := &response1{
Page: 1,
Fruits: []string{"apple", "peach", "pear"}}
res1B, _ := json.Marshal(res1D)
fmt.Println(string(res1B))
// You can use tags on struct field declarations// to customize the encoded JSON key names. Check the// definition of `response2` above to see an example// of such tags.
res2D := &response2{
Page: 1,
Fruits: []string{"apple", "peach", "pear"}}
res2B, _ := json.Marshal(res2D)
fmt.Println(string(res2B))
// Now let's look at decoding JSON data into Go// values. Here's an example for a generic data// structure.
byt := []byte(`{"num":6.13,"strs":["a","b"]}`)
// We need to provide a variable where the JSON// package can put the decoded data. This// `map[string]interface{}` will hold a map of strings// to arbitrary data types.var dat map[string]interface{}
// Here's the actual decoding, and a check for// associated errors.if err := json.Unmarshal(byt, &dat); err != nil {
panic(err)
}
fmt.Println(dat)
// In order to use the values in the decoded map,// we'll need to cast them to their appropriate type.// For example here we cast the value in `num` to// the expected `float64` type.
num := dat["num"].(float64)
fmt.Println(num)
// Accessing nested data requires a series of// casts.
strs := dat["strs"].([]interface{})
str1 := strs[0].(string)
fmt.Println(str1)
// We can also decode JSON into custom data types.// This has the advantages of adding additional// type-safety to our programs and eliminating the// need for type assertions when accessing the decoded// data.
str := `{"page": 1, "fruits": ["apple", "peach"]}`
res := response2{}
json.Unmarshal([]byte(str), &res)
fmt.Println(res)
fmt.Println(res.Fruits[0])
// In the examples above we always used bytes and// strings as intermediates between the data and// JSON representation on standard out. We can also// stream JSON encodings directly to `os.Writer`s like// `os.Stdout` or even HTTP response bodies.
enc := json.NewEncoder(os.Stdout)
d := map[string]int{"apple": 5, "lettuce": 7}
enc.Encode(d)
}
결과 :
true12.34"gopher"
["apple","peach","pear"]
{"apple":5,"lettuce":7}
{"Page":1,"Fruits":["apple","peach","pear"]}
{"page":1,"fruits":["apple","peach","pear"]}
map[num:6.13 strs:[a b]]
6.13
a
{1 [apple peach]}
apple
{"apple":5,"lettuce":7}
출처 : https://gobyexample.com/json
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