Svelte store for Automerge Repo

A reactive Svelte store for Automerge documents. Compatible with Svelte 3, 4, and 5.

Installation

npm install @automerge/automerge-repo-svelte-store

Example Usage

Basic Usage

<script>
  import { Repo } from "@automerge/automerge-repo"
  import { createAutomergeStore } from "@automerge/automerge-repo-svelte-store"

  // Create a repo
  const repo = new Repo({
    // Configuration...
  })

  // Create a store from the repo
  const automergeStore = createAutomergeStore(repo)

  // Load or create a document
  let documentStore = null

  async function loadDocument(url) {
    documentStore = await automergeStore.find(url)
  }

  async function createDocument() {
    documentStore = await automergeStore.create({ count: 0 })
  }

  // Update the document
  function incrementCounter() {
    if (documentStore) {
      documentStore.change(doc => {
        doc.count = (doc.count || 0) + 1
      })
    }
  }
</script>

Using with Svelte Context (recommended)

<!-- App.svelte -->
<script>
  import { Repo } from "@automerge/automerge-repo"
  import { setContextRepo } from "@automerge/automerge-repo-svelte-store"
  import Counter from './Counter.svelte'

  const repo = new Repo({
    // Configuration...
  })

  // Make repo available to child components
  setContextRepo(repo)

  // Create a document asynchronously
  let docUrl = null

  async function setupDoc() {
    const handle = await repo.create({ count: 0 })
    docUrl = handle.url
  }

  setupDoc()
</script>

{#if docUrl}
  <Counter {docUrl} />
{:else}
  <p>Creating document...</p>
{/if}

<!-- Counter.svelte -->
<script>
  import { document } from "@automerge/automerge-repo-svelte-store"
  import { onMount } from "svelte"

  export let docUrl

  // The document store - initially null
  let docStore = null

  // Load the document on mount
  onMount(async () => {
    // document() is async and returns a Promise
    docStore = await document(docUrl)
  })

  function increment() {
    if (!docStore) return

    // Access the document using the Svelte store $ syntax
    docStore.change(doc => {
      doc.count = (doc.count || 0) + 1
    })
  }
</script>

{#if docStore}
  <button on:click={increment}>
    Count: {$docStore.count || 0}
  </button>
{:else}
  <p>Loading document...</p>
{/if}

Using with Svelte 5 Runes

With Svelte 5, you can use the store with runes syntax for a more ergonomic experience:

<script>
  import { document } from "@automerge/automerge-repo-svelte-store"

  export let docUrl

  // Initialize state
  let docStore = $state(null)
  let loading = $state(true)
  let error = $state(null)
  let count = $derived(docStore?.$doc?.count || 0)

  // Load document when component initializes
  $effect(() => {
    async function loadDocument() {
      try {
        loading = true
        docStore = await document(docUrl)
        loading = false
      } catch (err) {
        console.error("Failed to load document:", err)
        error = err
        loading = false
      }
    }

    loadDocument()
  })

  function increment() {
    if (docStore) {
      docStore.change(doc => {
        doc.count = (doc.count || 0) + 1
      })
    }
  }
</script>

{#if loading}
  <p>Loading document...</p>
{:else if error}
  <p>Error: {error.message}</p>
{:else}
  <button on:click={increment}>
    Count: {count}
  </button>
{/if}

API Reference

createAutomergeStore(repo)

Creates an Automerge store factory from a repo instance.

setContextRepo(repo)

Sets the Automerge repo in the current component's context.

getContextRepo()

Gets the Automerge repo from the current component's context.

document(docIdOrUrl, repoInstance?)

Convenience method to load a document from the repo in context or a provided repo. Important: This function returns a Promise that resolves to the document store.

Store API

The document store returned by find() and create() implements Svelte's writable store contract with these additional methods:

• change(fn): Make changes to the document
• url: Get the document URL
• documentId: Get the document ID
• handle: Access the underlying Automerge document handle

Contributors

Originally written by Dylan MacKenzie (@ecstatic-morse). Updated for Svelte 5 compatibility by the Automerge team.