JSON schema middleware and valide helpers for Go

middleware.go

import (
	"context"
	"net/http"

	"github.com/Sirupsen/logrus"
	"github.com/matryer/respond"
)

func CheckJSON(log *logrus.Logger, h http.Handler, data interface{}, contextKey string) http.HandlerFunc {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		valid, err := ReadAndValidate(r, NotificationJSONSchema, data)

		if err != nil {
			log.Panicf("can't read and validate data against schema: %v", err)
			respond.WithStatus(w, r, http.StatusInternalServerError)
			return
		}

		if !valid {
			respond.WithStatus(w, r, http.StatusBadRequest)
			return
		}

		ctx := context.WithValue(r.Context(), contextKey, data)
		h.ServeHTTP(w, r.WithContext(ctx))
	})
}

validate.go

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"net/http"

	"github.com/xeipuuv/gojsonschema"
)

func ReadAndValidate(r *http.Request, schema string, n interface{}) (bool, error) {
	b, err := ioutil.ReadAll(r.Body)
	if err != nil {
		return false, err
	}
	defer r.Body.Close()
	documentLoader := gojsonschema.NewBytesLoader(b)
	schemaLoader := gojsonschema.NewStringLoader(schema)

	result, err := gojsonschema.Validate(schemaLoader, documentLoader)

	if err != nil {
		return false, fmt.Errorf("can't create validator: %v", err)
	}

	if !result.Valid() {
		return false, nil
	}

	if err := json.NewDecoder(bytes.NewReader(b)).Decode(&n); err != nil {
		return false, fmt.Errorf("can't decode json: %v", err)
	}

	return true, nil
}