An example of a method to parse json data using Golang

This paper is mainly about the Golang analysis of json data related content, to share for your reference and learning, the following is not enough to say, let's have a look at the detailed introduction:

Parse json data using Golang, the json format is an array of objects, the official document has an example:

var jsonBlob = []byte(`[ 
 {"Name": "Platypus", "Order": "Monotremata"}, 
 {"Name": "Quoll", "Order": "Dasyuromorphia"} 
]`) 
type Animal struct { 
 Name string 
 Order string 
} 
var animals []Animal 
err := json.Unmarshal(jsonBlob, &animals) 
if err != nil { 
 fmt.Println("error:", err) 
} 
fmt.Printf("%+v", animals)

It can parse the object of json data into the corresponding structure.

If it is a one dimensional array, with key-value pairs, such as: {" A ":3," B ":3," C ":5," D ":5}, the code is as follows:

func main() {
 jsonData := []byte(`{"A":3,"B":3,"C":5,"D":5}`)
 var a map[string]int
 json.Unmarshal(jsonData, &a)
 fmt.Printf("%+v\n", a)
}

You can see that json in key-value pair form can be mapped to map, or interface{} .

If it is a value-only form such as [" a ", "b", "c", "d", "e"], the code is as follows:

func main() {
 jsonData := []byte(`["a","b","c","d","e"]`)
 var a []string
 json.Unmarshal(jsonData, &a)
 fmt.Printf("%+v\n", a)
}

You can see that only value forms can be mapped to 1 slice.

About json data parsing For types, it is explained in the function comments:

To unmarshal JSON into an interface value,Unmarshal stores one of these in the interface value:
bool, for JSON booleans
float64, for JSON numbers
string, for JSON strings
[]interface{}, for JSON arrays
map[string]interface{}, for JSON objects
nil for JSON null

Simulation of the PHP json_decode($jsonString, true) function

But, in this case, in PHP, if you use json_decode(‘[“a”,”b”,”c”,”d”,”e”]', true) The second parameter is true's parse json, which can be resolved into the form of an object with key-value pairs:

[
 0=>"a",
 1=>"b",
 2=>"c",
 3=>"d",
 4=>"e"
]

How does this Golang do it?

func main() {
 jsonData := []byte(`["a","b","c","d","e"]`)
 var a []string
 json.Unmarshal(jsonData, &a)
 
 newData := make(map[int]string)
 for k, v := range a {
 newData[k] = v
 }
 
 fmt.Printf("%+v\n", newData)
}

There should be no built-in functions, so implement them manually.

conclusion