notion-fetcher.js

const { Client } = require("@notionhq/client")
const fs = require("fs")

// Initializing a client
const notion = new Client({
  auth: process.env.NOTION_TOKEN,
})

async function getPagesInDB() {
  const pagesByID = (
    await notion.databases.query({
      database_id: "a23022c1-9fa0-4b20-a4ca-5434eb4c1c9f",
    })
  ).results.map(({ id }) => id)

  return pagesByID
}

function getTextFromBlocks(blocks) {
  let content = ""

  for (const block of blocks) {
    content = content.concat(parseBlockForText(block))

    content = content.concat(parseBlockForHeading(block))
  }

  return content
}

function parseBlockForHeading(block) {
  let content = ""
  for (let i = 1; i <= 6; i++) {
    const parsedHeading = block[`heading_${i}`]?.text.map(textObject => {
      return `${textObject["plain_text"]}`
    })

    if (parsedHeading?.length > 0 && typeof parsedHeading !== undefined) {
      const headingWithNewLine = `##${parsedHeading.join("\n")}\n`
      content = content.concat(headingWithNewLine)
    }
  }

  return content
}

function parseBlockForText(block) {
  let content = ""
  const parsedText = block.paragraph?.text.map(
    textObject => `${textObject["plain_text"]}`
  )

  if (parsedText?.length > 0 && typeof parsedText !== undefined) {
    const heading = `${parsedText.join("\n")}\n`
    content = content.concat(heading)
  }
  return content
}

async function generateMarkDownFromInfo(page, block) {
  const title = page.properties["Name"].title[0].text.content

  const date = page.properties["date"]?.date.start || ""
  const description =
    page.properties["description"]["rich_text"]?.[0].text.content || ""
  const type = page.properties["type"].select.name
  const blocksResult = block.results
  const tags = page.properties["tags"]["multi_select"]
    .map(({ name }) => name.toLowerCase())
    .toString()

  const content = getTextFromBlocks(blocksResult)

  const result = `---
  title: ${title}
  date: "${date}"
  type: ${type}
  description: ${description}
  tags: [${tags}]
---
${content}
  `
  return result
}

async function fetchAndCreatePage(pageId) {
  const page = await notion.pages.retrieve({
    page_id: pageId,
  })

  const block = await notion.blocks.children.list({ block_id: pageId })

  const content = await generateMarkDownFromInfo(page, block)
  const slug = page.properties["slug"]["rich_text"]?.[0].text.content || ""
  const type = page.properties["type"].select.name

  if (type === "draft") return

  try {
    await fs.writeFileSync(`./content/blog/${slug}.md`, content)
    console.log("Writing file for ", slug)
  } catch (e) {
    console.error("Error saving md file for ", slug, e)
  }
}

async function callNotionAndCreatePages() {
  const pagesByID = await getPagesInDB()
  for (const pageId of pagesByID) {
    fetchAndCreatePage(pageId)
  }
}

callNotionAndCreatePages()