github.com/jasonccox/jsonbody

jsonbody

jsonbody is a Golang middleware library that makes receiving JSON web request bodies, validating them, and sending JSON response bodies easy.

Installation

Just run go get github.com/jasonccox/jsonbody and import github.com/jasonccox/jsonbody in your code.

Examples

Using the Middleware in a Route

The following code creates a middleware function that will ensure all requests to the /turtle route have a body matching the given schema.

import "github.com/jasonccox/jsonbody"

func main() {

	// create the middleware function - a func(next http.Handler) http.Handler
    middleware := jsonbody.NewMiddleware(`{
        "name": "",
        "age": 0,
        "details": {
            "?species": "",
            "aquatic": false
        },
        "children": ["name"]
    }`)

	// use the middleware in the route
	http.Handle("/turtle", middleware(myHandler{})

	...
}

Handling the Request

The following code uses the jsonbody.Reader and jsonbody.Writer to handle a POST request.

import "github.com/jasonccox/jsonbody"

type myHandler struct {}

func (h myHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		w.WriteHeader(http.StatusNotFound)
		return
	}

	jsonWriter, ok := w.(jsonbody.Writer)
	if !ok {
		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	jsonReader, ok := r.Body.(jsonbody.Reader)
	if !ok {
		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	jsonBody := jsonReader.JSON() // returns a map[string]interface{} representing the request body

	turt := turtle{
		name:     jsonBody["name"].(string), // we can safely assert the type because the middleware already checked it
		age:      jsonBody["age"].(float64), // JSON numbers are represented as float64
		children: jsonBody["children"].([]string)
	}

	turtDetails := jsonBody["details"].(map[string]interface{}) // JSON objects are represented as map[string]interface{}
	turt.aquatic = turtDetails["aquatic"].(bool)

	if s, ok := turtDetails["species"]; ok { // details.species was optional, so we need to make sure it was set before using it
		turt.species = s.(string)
	}

	if turt.age < 0.0 {
		jsonWriter.WriteErrors(http.StatusBadRequest, "age must be positive") // sends back an error body
		return
	}

	// do some processing here...

	jsonWriter.WriteJSON(http.StatusCreated, turt) // converts turt to JSON and writes it as the response body
}

Documentation

For more in-depth information, check out the godoc.