JSON: Difference between revisions
→{{header|Go}}: added example more applicable to real world problems. for existing example, simplified one point, added an error check, output, and description
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=={{header|Go}}==
Example below shows simple correspondence between JSON objects and Go maps, and shows that you don't have to know anything about the structure of the JSON data to read it in.
<lang go>package main
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func main() {
var data
err := json.Unmarshal([]byte(`{"foo":1, "bar":[10, "apples"]}`), &data)
if err == nil {
fmt.Println(data)
} else {
fmt.Println(err)
}
sample := map[string]interface{}{
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}
}</lang>
Output:
<pre>
map[bar:[10 apples] foo:1]
{"blue":[1,2],"ocean":"water"}
</pre>
Example below demonstrates more typical case where you have an expected correspondence between JSON data and some composite data types in your program, and shows how the correspondence doesn't have to be exact.
<lang>package main
import "encoding/json"
import "fmt"
type Person struct {
Name string `json:"name"`
Age int `json:"age,omitempty"`
Addr *Address `json:"address,omitempty"`
Ph []string `json:"phone,omitempty"`
}
type Address struct {
Street string `json:"street"`
City string `json:"city"`
State string `json:"state"`
Zip string `json:"zip"`
}
func main() {
// compare with output, note apt field ignored, missing fields
// have zero values.
jData := []byte(`{
"name": "Smith",
"address": {
"street": "21 2nd Street",
"apt": "507",
"city": "New York",
"state": "NY",
"zip": "10021"
}
}`)
var p Person
err := json.Unmarshal(jData, &p)
if err != nil {
fmt.Println(err)
} else {
fmt.Printf("%+v\n %+v\n\n", p, p.Addr)
}
// compare with output, note empty fields omitted.
pList := []Person{
{
Name: "Jones",
Age: 21,
},
{
Name: "Smith",
Addr: {"21 2nd Street", "New York", "NY", "10021"},
Ph: {"212 555-1234", "646 555-4567"},
},
}
jData, err = json.MarshalIndent(pList, "", " ")
if err != nil {
fmt.Println(err)
} else {
fmt.Println(string(jData))
}
}</lang>
Output:
<pre>
{Name:Smith Age:0 Addr:0xf840026080 Ph:[]}
&{Street:21 2nd Street City:New York State:NY Zip:10021}
[
{
"name": "Jones",
"age": 21
},
{
"name": "Smith",
"address": {
"street": "21 2nd Street",
"city": "New York",
"state": "NY",
"zip": "10021"
},
"phone": [
"212 555-1234",
"646 555-4567"
]
}
]
</pre>
=={{header|Groovy}}==
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