veun

A small server-side HTML template composition library for Go.

Read more: Building View-Trees in Go (7-part series) · Demo · Demo source

Overview

veun is a composable view library built on top of Go's standard html/template package. The core idea: a View pairs an HTML renderable with an optional error handler, and views compose into trees.

Packages

Package	Purpose
github.com/stanistan/veun	Core types and Render function
github.com/stanistan/veun/template	html/template-based views with slot composition
github.com/stanistan/veun/el	Functional HTML element construction (codegen'd)
github.com/stanistan/veun/vhttp	http.Handler integration
github.com/stanistan/veun/vhttp/handler	Handler utilities (checked, path, status)
github.com/stanistan/veun/vhttp/request	Request handler interface

Core Concepts

AsView

Any type implementing View(context.Context) (*View, error) is an AsView and can be rendered.

type personView struct{ Name string }

func (v personView) View(_ context.Context) (*veun.View, error) {
    tpl := template.Must(template.New("").Parse(`<div>Hi, {{ .Name }}.</div>`))
    return veun.V(t.Template{Tpl: tpl, Data: v}), nil
}

html, err := veun.Render(ctx, personView{Name: "Stan"})
// html == `<div>Hi, Stan.</div>`

Slot composition

Templates can render child views into named slots:

var containerTpl = t.MustParse("container", `
    <div>
        <header>{{ slot "heading" }}</header>
        <main>{{ slot "body" }}</main>
    </div>
`)

func (v ContainerView) View(_ context.Context) (*veun.View, error) {
    return veun.V(t.Template{
        Tpl:   containerTpl,
        Slots: t.Slots{"heading": v.Heading, "body": v.Body},
    }), nil
}

el — functional element construction

view := el.Div{
    el.Class("container"),
    el.H1{el.Text("Hello")},
    el.P{el.Text("World")},
}

Error handling

Any view can attach an error handler that either replaces failed content or propagates the error:

view := veun.V(myView).WithErrorHandler(veun.ErrorHandlerFunc(
    func(ctx context.Context, err error) (veun.AsView, error) {
        return fallbackView{}, nil
    },
))

HTTP handlers

mux.Handle("/", vhttp.HandlerFunc(func(r *http.Request) (veun.AsView, http.Handler, error) {
    return myPageView{}, nil, nil
}))

Install

go get github.com/stanistan/veun