goreactive

goreactive - reactive template variables with WebSockets

goreactive allows you to build web applications such as dashboards that update in real-time without writing any JavaScript. Use standard Go templates, embed them with ReactiveVar objects and the library takes care of the rest. Updates are pushed to clients over Websockets.

Install

go get github.com/antvirf/goreactive

Example

package main

import (
	"fmt"
	"log"
	"math/rand/v2"
	"net/http"
	"text/template"
	"time"

	"github.com/antvirf/goreactive"
)

var pageData PageData

type PageData struct {
	ReactiveVarsScriptBlock string
	ReactiveVars            []*goreactive.ReactiveVar
}

func serveIndex(w http.ResponseWriter, r *http.Request) {
	template.Must(template.New("index").Parse(`
  {{ .ReactiveVarsScriptBlock }}
  <h1>Goreactive example</h1>
  <ul>
  {{ range .ReactiveVars}}
    <li>
      {{ . }}
    </li>
  {{ end  }}
  </ul>
    `)).Execute(w, pageData)
}

func main() {
	// Create a reactive var
	example_one := goreactive.NewReactiveVar("28")

	// Set up data to pass to our templates
	pageData = PageData{
		ReactiveVars: []*goreactive.ReactiveVar{example_one},
		ReactiveVarsScriptBlock: goreactive.WebsocketJavascriptBlock,
	}

	// Start updating our variable in the background
	go func() {
		for {
			<-time.After(time.Duration(rand.IntN(1000)) * time.Millisecond)
			example_one.Update(fmt.Sprintf("%d", rand.IntN(1000)))
		}
	}()

	// Set up an HTTP server as we normally would
	// Add handler for template + websocket
	mux := http.NewServeMux()
	mux.HandleFunc("/", serveIndex)
	mux.HandleFunc("/reactiveVarsWebsocket", goreactive.WebsocketServerHandler)

	handler := http.Handler(mux)
	log.Fatal(http.ListenAndServe(":8080", handler))
}

Major missing features

• Server-side
  • Authentication
  • Review 'nicer'/proper ways to handle closing the messageBroker channel etc. when the application is stopped
  • Some way to customise the printing format of variables, or allow further customisation of what is sent to the client
  • Tests + load tests (how many websocket subscriptions can we handle?)
  • Customisable/passable logger to get information out from the package
• Client-side
  • Inform client on error/disconnect
  • Automatic attempts to redirect to client