gomodest-template

A modest template to build dynamic web apps in Go, HTML and sprinkles and spots of javascript.

Why ?

• Build dynamic websites using the tools you already know(Go, HTML, CSS, Vanilla Javascript) for the most part.
• Use bulma components to speed up prototyping a responsive and good-looking UI.
• Use turbo & stimulusjs for most of the interactivity.
• For really complex interactivity use Svelte for a single div in a few spots.
• Lightweight and productive. Fast development cycle.
• Easy to start, easy to maintain.

For a more complete implementation using this technique please see gomodest-starter.

Usage

• Use as a github template
• git clone https://github.com/<user>/<mytemplate> and cd /path/to/your/gomodest-template
• make watch (starts hot-reload for go, html and javascript changes)
• open localhost:3000.

or

brew install gh
gh repo create myapp --template adnaan/gomodest-template
cd myapp
make install # or (make install-x64)
# replace gomodest-template with your app name
go get github.com/piranha/goreplace
$(go env GOPATH)/bin/goreplace gomodest-template -r myapp
git add . && git commit -m "replace gomodest-template"
make watch # or make watch-x64

TOC

• Folder Structure
• Views using html templates
  • Step 1: Add a layout partial
  • Step 2: Add a layout
  • Step 4: Add a view partial
  • Step 5: Add a view
  • Step 6: Render view
• Interactivity using Javascript
  • Stimulus Controllers
    • Step 1: Add a controller
    • Step 2: Add data attributes to the target div
  • Svelte Components
    • Step 1: Add data attributes to the target div.
    • Step 2: Create and export svelte component
    • Step 3: Hydrate initial props from the server
• Styling and Images
• Samples
• Dependencies

Table of contents generated with markdown-toc

Folder Structure

• templates/

  • layouts/
  • partials/
  • list of view files

• assets/

  • images/

  • src/

    • components/
    • controllers/
    • index.js
    • styles.scss

• templates is the root directory where all html/templates assets are found.

• layouts contains the layout files. Layout is a container for partials and view files

• partials contains the partial files. Partial is a reusable html template which can be used in one of two ways:

  • Included in a layout file: {{include "partials/header"}}

  • Included in a view file: {{template "main" .}}. When used in a view file, a partial must be enclosed in a define tag:

        {{define "main"}}
          Hello {{.hello}}
        {{end}}
    

• view files are put in the root of the templates directory. They are contained within a layout must be enclosed in a define content tag:

      {{define "content"}}
          App's {{.dashboard}}
      {{end}}
  

  View is rendered within a layout:

      indexLayout, err := rl.New(
  rl.Layout("index"),
  rl.DisableCache(true),
  rl.DefaultHandler(func(w http.ResponseWriter, r *http.Request) (rl.M, error) {
  	return rl.M{
  		"app_name": "gomdest-template",
  	}, nil
  }))
  
      ...
  
      r.Get("/", indexLayout.Handle("home",
  func(w http.ResponseWriter, r *http.Request) (rl.M, error) {
  	return rl.M{
  		"hello": "world",
  	}, nil
  }))
  

  Here the view: home is rendered within the index layout.

Please see the templates directory.

• assets directory contains the public asset pipeline for the project.

  • styles.scss is a custom scss file for [bulma][https://bulma.io] as documented here.
  • index.js is the entrypoint for loading stimulusjs controllers sourced from this [example](https://github.com/hotwired/stimulus-starter.
  • controllers contains stimulusjs controllers.
  • components contains single file svelte components.

Views using html templates

There are three kinds of html/template files in this project.

• layout: defines the base structure of a web page.
• partial: reusable snippets of html. It can be of two types: layout partials & view partials.
• view: the main container for the web page logic contained within a layout. It must be enclosed in a define content template definition. It can use view partials.

Step 1: Add a layout partial

Create header.html file in templates/partials.

<meta charset="UTF-8">
<meta name="description" content="A modest way to build golang web apps">
<meta name="viewport"content="width=device-width, initial-scale=1.0, maximum-scale=5.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
...

Step 2: Add a layout

Create index.html file in templates/layouts and use the above partial.

<!DOCTYPE html>

<html lang="en">
<head>
    <title>{{.app_name}}</title>
    {{include "partials/header"}}
</head>
<body ...>
...
</body>
</html>

Step 4: Add a view partial

Create main.html in templates/partials

{{define "main"}}
    <main>
        <div class="columns is-centered is-vcentered is-mobile py-5">
            <div class="column is-narrow" style="width: 70%">
                <h1 class="has-text-centered title">Hello {{.hello}}</h1>
            </div>
        </div>
    </main>
{{end}}

This is a different from the layout partial since it's closed in a define tag.

Step 5: Add a view

Create home.html in templates and use the above partial.

{{define "content"}}
<div class="columns is-mobile is-centered">
    <div class="column is-half-desktop">
        {{template "main" .}}
    </div>
</div>
{{end}}

Notice that a view is always enclosed in define content template definition.

Step 6: Render view

To render the view with data we use a wrapper over the html/template package.

r.Get("/", indexLayout.Handle("home",
    func(w http.ResponseWriter, r *http.Request) (rl.M, error) {
        return rl.M{
            "hello": "world",
    }, nil
}))

To learn more about html/template, please look into this amazing cheatsheet.

Reference:

• templates/layout/index.html
• templates/partials/header.html
• templates/partials/main.html
• templates/home.html
• main.go

Interactivity using Javascript

For client-side interactivity we use a bit of javascript.

Stimulus Controllers

A stimulus controller is a snippet of javascript which handles a single aspect of interactivity. To add a new svelte component:

Step 1: Add a controller

Create a file with suffix: _controller.js

util_controller.js

import { Controller } from "stimulus"

export default class extends Controller {
  ...

    connect(){

    }

    goto(e){
        if (e.currentTarget.dataset.goto){
            window.location = e.currentTarget.dataset.goto;
        }
    }

    goback(e){
       window.history.back();
    }

   ...
}

See complete implementation in assets/src/controller/util_controller.js. To understand how stimulus works, please see the handbook.

Step 2: Add data attributes to the target div

<body data-controller="util svelte"
      data-action="keydown@window->util#keyDown "
      data-util-active-class="is-active">
  
    ...
  <button class="button"
    data-action="click->util#goto"
    data-goto="/">Home
  </button>
</body>

Here we are attaching two controllers to the body itself since they are used often. Later we can add action and data attributes to use them.

Reference:

• templates/layout/index.html
• templates/404.html
• assets/src/controllers/util_controller.js

Svelte Components

A svelte component is loaded into the targeted div by a stimulujs controller: controllers/svelte_controller.js. This is hooked by declaring data attributes on the div which is to be contain the svelte component:

• data-svelte-target: Value is required to be component. It's used for identifying the divs as targets for the svelte_controller.

• data-component-name: The name of the component as exported in src/components/index.js

    import app from "./App.svelte"
    // export other components here.
    export default {
        app: app,
    }
  

• data-component-props: A string map object which is passed as initial props to the svelte component.

To add a new svelte component:

Step 1: Add data attributes to the target div.

{{define "content"}}
<div class="columns is-mobile is-centered">
 <div class="column is-half-desktop">
  <div
          data-svelte-target="component"
          data-component-name="app"
          data-component-props="{{.Data}}">
  </div>
 </div>
</div>
</div>
{{end}}

Step 2: Create and export svelte component

• Create a new svelte component in src/components and export it in src/components/index.js

import app from "./App.svelte"

// export other components here.
export default {
    app: app,
}

The controllers/svelte_controller.js controller loads the svelte component in to the div with the required data attributes shown in step 1.

Step 3: Hydrate initial props from the server

It's possible to hydrate initial props from the server and pass onto the component. This is done by templating a string data object into the data-component-props attribute.

r.Get("/app", indexLayout.Handle("app",
    func(w http.ResponseWriter, r *http.Request) (rl.M, error) {
      appData := struct {
      Title string `json:"title"`
      }{
      Title: "Hello from server for the svelte component",
      }
    
      d, err := json.Marshal(&appData)
      if err != nil {
      return nil, fmt.Errorf("%v: %w", err, fmt.Errorf("encoding failed"))
      }
    
      return rl.M{
      "Data": string(d), // notice struct data is converted into a string
      }, nil
}))

Reference:

• templates/app.html
• src/controllers/svelte_controller.js
• src/components/*
• main.go

Styling and Images

Bulma is included by default. Bulma is a productive css framework with prebuilt components and helper utilities.

• assets/src/styles.scss: to override default bulma variables. webpack bundles and copies css assets to `public/assets/css.
• assets/images: put image assets here. it will be auto-copied to public/assets/images by webpack.

Samples

Go to localhost:3000/samples to a list of sample views. Copy-paste at will from the templates/samples directory.

Dependencies

• Backend:
  • Go
  • renderlayout: a wrapper over foolin/goview
  • chi
• Frontend:
  • html/template
  • masterminds/sprig
  • StimulusJS(sprinkles)
  • SvelteJS(spots)
  • Bulma CSS
  • Webpack