ssg

Sapper Site Generator

a very experimental static site generator overlay on top of Sapper. For a simple demo see this:

https://www.youtube.com/watch?v=o_o0PAts9Gg&feature=youtu.be

Because Sapper needs fixes to support static export at scale, we use a light fork of Sapper (https://github.com/sw-yx/sapper) instead of sapper itself. Hopefully this fork will not be necessary in future, but for now we need these fixes for ssg to work.

Installation

yarn add @ssgjs/sapper svelte ssg

What it expects

1. you will have a src/routes/data/[ssgData].json.js file in your main Sapper project, that looks like this:

// src/routes/data/[ssgData].json.js`
const { getDataSlice, getIndex } = require('ssg/readConfig')

export async function get(req, res) {
  const { ssgData } = req.params
  const splitSlug = ssgData.split('___ssg___')
  const key = splitSlug[0]
  const uid = splitSlug[1]
  const mainIndex = getIndex()
  let data
  // console.log('getting', key, uid)
  if (uid === 'index') {
    data = mainIndex[key]
  } else {
    data = await getDataSlice(key, uid)
  }
  if (typeof data !== 'undefined') {
    res.writeHead(200, { 'Content-Type': 'application/json' })
    res.end(JSON.stringify(data))
  } else {
    res.writeHead(404, { 'Content-Type': 'application/json' })
    res.end(JSON.stringify({ message: `Not found` }))
  }
}

> ⚠️ STOP! the filename is extremely important! doublecheck it is `src/routes/data/[ssgData].json.js``

1. You should have a ssg.config.js that exports a createIndex (run once) and getDataSlice (run each time) function that provides this data:

// optional. called repeatedly, can be expensive
exports.getDataSlice = async (key, uid) => {
  console.log('optional getDataSlice action')
  // we dont really use the key here
  if (key === 'posts') {
    if (uid === 'foo') {
      return { title: 'foo', html: '<div> the foo post </div>' }
    } else {
      return { title: 'bar', html: '<div> the bar post </div>' }
    }
  } else {
    throw new Error('invalid key ' + key )
  }
}

exports.createIndex = async (mainIndex = {}) => {
  // do expensive initial fetches and cache them in .ssg/data.json
  mainIndex.index = [{ title: 'foo', slug: 'foo' }, { title: 'bar', slug: 'bar' }]
  return mainIndex
}

// optional lifecycle hook
exports.postExport = async mainIndex => {
  // eg for RSS
  console.log('postExport', mainIndex)
}

In your templates, you may now query this data at any time:

<!-- src/routes/talks/[slug].svelte -->
<script context="module">
  export async function preload({ params, query }) {
    cosnt key = 'posts'
    const res = await this.fetch(`data/${key}___ssg___${params.slug}.json`)
    const data = await res.json()
    if (res.status === 200) {
      return { post: data }
    } else {
      this.error(res.status, data.message)
    }
  }
</script>

What it does

Under the hood, ssg runs sapper dev for you, and watches and reloads it whenever you change your config or contents folder.

It runs createIndex once and saves that result to a cache, and then you can run getDataSlice anytime you want to query that cache.

Plugins

You can also use plugins that have prewritten createIndex and getDataSlice for you:

// ssg.config.js
const remark = require('@ssgjs/source-remark')
const writing = remark({ dirPath: 'content/writing' })
const speaking = remark({ dirPath: 'content/talks' })

// optional data plugins. must be object, so we can namespace
exports.plugins = {
  writing,
  speaking
}