Golang in sixty seconds — converting to JSON

Go has a really nice way to convert to JSON. To convert from a Go type to JSON is called marshalling.

Let's look at an example:

type person struct {
  Name string
}
func main() {
  m := person{Name: "Mike"}
  mj, _ := json.Marshal(m)
  fmt.Println(string(mj)) //{"Name":"Mike"}
}

Here you can see that we have defined our custom type person, and created m which has type person. The json.Marshal function will use the fields in your type as the key names. You can also use standard Go types like strings, ints, structs etc. Lets make this example slightly more complicated to explain a few other details:

type person struct {
  Name string `json:"First name"`
  age  int    
}
func main() {
  m := person{Name: "Mike", age: 25}
  mj, _ := json.Marshal(m)
  fmt.Println(string(mj)) //{"First name":"Mike"}
}

This time we have a second field on our type without an uppercase letter at the start. This means that this field is not exported, and as a result, json.Marshal does not put this field into the JSON. The other thing that we've added here is a “tag” ( `json:”First name”`). This means that instead of using Name as our JSON key, "First name” will be used instead.

You can see this example here.

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