Algolia + Sanity.io + Gatsby queries

algolia-queries.js

const escapeStringRegexp = require("escape-string-regexp")

// const pagePath = `content`
// const indexName = `Pages`

const pageQuery = `{
  pages: allMdx {
    edges {
      node {
        id
        frontmatter {
          title
        }
        fields {
          slug
        }
        excerpt(pruneLength: 5000)
      }
    }
  }
}`
const postQuery = `{
  posts: allSanityPost {
    edges {
      node {
        id
        title
        slug {
          current
        }
        _rawExcerpt
      }
    }
  }
}`

function pageToAlgoliaRecord({ node: { id, frontmatter, fields, ...rest } }) {
  return {
    objectID: id,
    ...frontmatter,
    ...fields,
    ...rest,
  }
}

function postToAlgoliaRecord({ node: { id, slug, ...rest } }) {
  return {
    objectID: id,
    ...slug,
    ...rest,
  }
}

const queries = [
  {
    query: pageQuery,
    transformer: ({ data }) => data.pages.edges.map(pageToAlgoliaRecord),
    indexName: `Pages`,
    settings: { attributesToSnippet: [`excerpt:20`] },
  },
  {
    query: postQuery,
    transformer: ({ data }) => data.posts.edges.map(postToAlgoliaRecord),
    indexName: `Posts`,
    settings: { attributesToSnippet: [`excerpt:20`] },
  },
]

module.exports = queries

For future reference, some idea for a better alternative approach by Corey Ward (@coreyward) from Sanity.io Slack channel:

In short, I used the Sanity webhooks to notify a serverless function wehn documents changed. On each invocation it fetches the relevant data from the changed documents, fetches related search index objects from Algolia, and then does simple comparison to see what changes need to be made to the index. Because Algolia works best with small objects and I wanted full text search, each “section” of the page is indexed individually but pointing to the page slug.