golang struct to json

Golang is a very popular programming language. It not only has strong concurrency performance, but also has a rich standard library and easy-to-read code. In Golang, struct is widely used. Struct can not only encapsulate data, but also facilitate serialization and deserialization. In this article, we will discuss how to convert struct in Golang to JSON format.

First, let us understand what JSON is. JSON, short for JavaScript Object Notation, is a lightweight data exchange format commonly used to transfer data between clients and servers. Compared with XML, JSON format is more concise and easier to read.

In Golang, converting struct to JSON format is very simple. We can accomplish this task through the built-in "encoding/json" package. Here is a simple code example that demonstrates how to convert a struct to JSON format:

package main

import (
    "encoding/json"
    "fmt"
)

type Person struct {
    Name string `json:"name"`
    Age  int    `json:"age"`
}

func main() {
    person := Person{Name: "Amy", Age: 30}
    personJSON, err := json.Marshal(person)
    if err != nil {
        fmt.Println(err)
    }
    fmt.Println(string(personJSON))
}

In this example, we define a struct type named Person and create an instance named person. We then use the json.Marshal() function to convert the person instance to JSON format and print the result to the console.

It should be noted that in the definition of Person struct, we added a "json" tag. This tag represents the key name used when converting the struct to JSON format. In this example, "name" and "age" are JSON key names, and Name and Age are the names of struct fields in Golang. If we do not specify a json tag for the struct field, the JSON key name will be the same as the field name.

type Person struct {
    Name string
    Age  int
}

In this example, the field names in the struct and the JSON key names are the same, so they will be automatically mapped.

In addition to using the json.Marshal() function to convert struct to JSON format, we can also use the json.Unmarshal() function to convert JSON format to struct. Here is a sample code:

package main

import (
    "encoding/json"
    "fmt"
)

type Person struct {
    Name string `json:"name"`
    Age  int    `json:"age"`
}

func main() {
    personJSON := `{"name":"Amy","age":30}`
    var person Person
    err := json.Unmarshal([]byte(personJSON), &person)
    if err != nil {
        fmt.Println(err)
    }
    fmt.Println(person.Name, person.Age)
}

In this example, we define a string named personJSON that contains Person instance data represented in JSON format. We then use the json.Unmarshal() function to convert the personJSON string to type Person and save the result in a variable named person. Finally, we print the name and age of the person instance.

It should be noted that in the json.Unmarshal() function, the first parameter is a byte type slice, which represents the JSON data to be converted into a struct. The second parameter is a pointer to the Person type, which represents the JSON data that will be decoded into an instance of this type.

In conclusion, converting struct in Golang to JSON format is a very simple task. We can do this using the built-in "encoding/json" package. By adding the "json" tag to the struct field, we can customize the JSON key name. Conversely, if no label is specified, the JSON key name will be the same as the field name. When doing JSON deserialization, make sure to pass the target type as a pointer so that the value of that type is updated when the function returns.

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