How to pretty print JSON in go (golang)

Use the json.Indent method to print JSON in go (golang)

Use json.Indent method

Code example on how to pretty print JSON in go (golang)

func handleRequest(w http.ResponseWriter, req *http.Request) {
    body := App.MustReadBody(req, w)  // get the respone body
    if body == nil {
        return
    }

    var prettyJSON bytes.Buffer
    error := json.Indent(&prettyJSON, body, "", "\t")
    if error != nil {
        fmt.Println("JSON parse error: ", error)
        App.BadRequest(w) // handle errors
        return
    }

    fmt.Println(prettyJSON.String())
}

In the code above we can see that all we have to do is to call json.Indent on our object. Printing this will give us the following result:

{
        "Id": 1,
        "Data": [
                "Cat",
                "Dog",
                "Horse"
        ]
}

Use the json.MarshalIndent method to print JSON in go (golang)

Use json.MarshalIndent method

Code example on how to pretty print JSON using json.MarshalIndent in go (golang)

Let's change the previous example to use json.MarshalIndent instead of json.Indent.

func handleRequest(w http.ResponseWriter, req *http.Request) {
    body := App.MustReadBody(req, w)  // get the respone body
    if body == nil {
        return
    }

    prettyJSON, error := json.MarshalIndent(myStruct, "", "\t")
    if error != nil {
        fmt.Println("JSON parse error: ", error)
        App.BadRequest(w) // handle errors
        return
    }

    fmt.Println(string(prettyJSON))
}

Printing the variable we get the same result as before:

{
        "Id": 1,
        "Data": [
                "Cat",
                "Dog",
                "Horse"
        ]
}

What is the difference between Indent and MarshalIndent

MarshalIndent will turn your existing object into a JSON object and indent it. Indent on the other hand will not will make a JSON transformation. That means if you only want to pretty print a byte array you should use json.Indent.

Pretty printing JSON in go (golang) is really not that difficult. If you want to read more on how to use the print function in go, printing structs in particular, you should check out this post or this post for the print formatter cheat sheet.