Store struct as string in redis

As Redis only stores strings I would like to know how I can do the equivalent of Javascript's JSON.stringify using Go to convert a Struct into a string.

I have tried typecasting:

string(the_struct)

but this results in an error.

The encoding/json package can be used to easily convert a struct to JSON string and vice versa (parse a JSON string into a struct).

Simple example (try it on the Go Playground):

type Person struct {
	Name string
	Age  int
}
func main() {
	p := Person{"Bob", 23}
	// Struct -> JSON
	data, err := json.Marshal(&p)
	if err != nil {
		panic(err)
	}
	fmt.Println(string(data))
	// JSON -> JSON
	var p2 Person
	err = json.Unmarshal(data, &p2)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%+v", p2)
}

Output:

{"Name":"Bob","Age":23}
{Name:Bob Age:23}

Notes:

The fields of the struct must be exported (start them with capital letter), else the json package (which uses reflection) will not be able to read/write them.

You can also specify tags for the struct fields to control/fine tune the json marshaling/unmarshaling process, for example to change the names in the JSON text:

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

With this change the output of the above application is the following:

{"name":"Bob","years":23}
{Name:Bob Age:23}

The documentation of the json.Marshal() function details the possibilities provided by the tags.

And by implementing the json.Marshaler and json.Unmarshaler interfaces you can fully customize the marshaling / unmarshaling process.

Also if your struct is not pre-defined (e.g. you don't know the fields in advance), you can use a map[string]interface{}. See this answer for details and examples.