HOWTO · Go
How to Convert JSON to Struct in Go
This tutorial demonstrates how to convert JSON to a struct in GoLang.
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This tutorial demonstrates how to convert JSON to a struct in GoLang.
Use the Unmarshal Method to Convert JSON to Struct in Go
The encoding/json package of GoLang provides a function Unmarshal, which converts JSON data to byte format. This function can parse the structured and non-structured JSON data into the []byte form.
We can use this byte conversion to convert the JSON to a struct. Let’s try an example to convert JSON to a struct using the Unmarshal method:
package main
import (
"encoding/json"
"fmt"
)
type Employee struct {
Name string
ID int
Salary int
Position string
}
func main() {
EmployeeJSON := `{"Name": "Sheeraz", "ID": 10, "Salary": 3000, "Position": "Senior Developer" }`
var employees Employee
json.Unmarshal([]byte(EmployeeJSON), &employees)
fmt.Printf("Name: %s, ID: %d , Salary: %d , Position: %s", employees.Name, employees.ID, employees.Salary, employees.Position)
fmt.Println("\n", employees)
}
The code above converts the given JSON to a struct by using the Unmarshal method of the JSON standard library of GoLang. See the output:
Name: Sheeraz, ID: 10 , Salary: 3000 , Position: Senior Developer
{Sheeraz 10 3000 Senior Developer}
Program exited.
Convert an Array of JSON to Struct in Go
As we can see, the above example converts a single JSON to a struct, but what if we have an array of JSON? Let’s try an example to convert the array of JSON to a struct:
package main
import (
"encoding/json"
"fmt"
)
type Employee struct {
Name string
ID int
Salary int
Position string
}
func main() {
EmployeeJSON := `[{"Name": "Sheeraz", "ID": 10, "Salary": 3000, "Position": "Senior Developer" },
{"Name": "Jack", "ID": 20, "Salary": 2000, "Position": "Junior Developer" },
{"Name": "John", "ID": 30, "Salary": 1500, "Position": "Junior Developer" },
{"Name": "Mike", "ID": 40, "Salary": 1000, "Position": "Intern" }
]`
var employees []Employee
json.Unmarshal([]byte(EmployeeJSON), &employees)
fmt.Printf("Employees Structs : %+v", employees)
}
The code above will convert the array of JSON to an array of structs. See the output:
Employees Structs : [
{Name:Sheeraz ID:10 Salary:3000 Position:Senior Developer}
{Name:Jack ID:20 Salary:2000 Position:Junior Developer}
{Name:John ID:30 Salary:1500 Position:Junior Developer}
{Name:Mike ID:40 Salary:1000 Position:Intern}]
Program exited.
Convert a Nested JSON to Struct in Go
JSONs are also created in a nested form where a field in JSON contains another field. To convert this type of JSONS, we have to create nested structs.
Let’s see an example:
package main
import (
"encoding/json"
"fmt"
)
type EmployeeType struct {
Gender string
Contract string
}
type Employee struct {
Name string
ID int
Salary int
Position string
EmployeeType EmployeeType
}
func main() {
EmployeeJSON := `{"Name": "Sheeraz", "ID": 10, "Salary": 3000, "Position": "Senior Developer", "EmployeeType": {"Gender": "Male" ,"Contract": "Fulltime"} }`
var employees Employee
json.Unmarshal([]byte(EmployeeJSON), &employees)
fmt.Printf("Name: %s, ID: %d , Salary: %d , Position: %s, Gender: %s, Contract: %s",
employees.Name, employees.ID, employees.Salary, employees.Position, employees.EmployeeType.Gender, employees.EmployeeType.Contract)
fmt.Println("\n", employees)
}
The code above will convert a nested JSON object to a nested struct. See the output:
Name: Sheeraz, ID: 10 , Salary: 3000 , Position: Senior Developer, Gender: Male, Contract: Fulltime
{Sheeraz 10 3000 Senior Developer {Male Fulltime}}
Program exited.
