Adds import method to add an existing document to the repo

packages/automerge-repo/README.md

@@ -45,6 +45,8 @@ A `Repo` exposes these methods:
   networks.
 - `delete(docId: DocumentId)`  
   Deletes the local copy of a document from the local cache and local storage. _This does not currently delete the document from any other peers_.
+- `import(binary: Uint8Array)`  
+  Imports a document binary (from `Automerge.save(doc)`) into the repo, returning a new handle
 - `.on("document", ({handle: DocHandle}) => void)`  
   Registers a callback to be fired each time a new document is loaded or created.
 - `.on("delete-document", ({handle: DocHandle}) => void)`  
@@ -64,7 +66,7 @@ the document.
 
 A `DocHandle` also emits these events:
 
-- `change({handle: DocHandle, patches: Patch[], patchInfo: PatchInfo})` 
+- `change({handle: DocHandle, patches: Patch[], patchInfo: PatchInfo})`
   Called whenever the document changes, the handle's .doc
 - `delete`  
   Called when the document is deleted locally.
@@ -85,11 +87,12 @@ network adapter:
 const repo = new Repo({
   network: [new BroadcastChannelNetworkAdapter()],
   storage: new IndexedDBStorageAdapter(),
-  sharePolicy: async (peerId: PeerId, documentId: DocumentId) => true // this is the default
+  sharePolicy: async (peerId: PeerId, documentId: DocumentId) => true, // this is the default
 })
 ```
 
 ### Share Policy
+
 The share policy is used to determine which document in your repo should be _automatically_ shared with other peers. **The default setting is to share all documents with all peers.**
 
 > **Warning**
@@ -99,13 +102,13 @@ You can override this by providing a custom share policy. The function should re
 
 The share policy will not stop a document being _requested_ by another peer by its `DocumentId`.
 
-```ts
+````ts
 ## Starting the demo app
 
 ```bash
 yarn
 yarn dev
-```
+````
 
 ## Quickstart
 
@@ -272,7 +275,8 @@ you'll need to manually copy the `rootDocId` value between the browsers.)
 Originally authored by Peter van Hardenberg.
 
 With gratitude for contributions by:
- - Herb Caudill
- - Jeremy Rose
- - Alex Currie-Clark
- - Dylan Mackenzie
+
+- Herb Caudill
+- Jeremy Rose
+- Alex Currie-Clark
+- Dylan Mackenzie

packages/automerge-repo/src/Repo.ts

@@ -442,6 +442,22 @@ export class Repo extends EventEmitter<RepoEvents> {
     this.emit("delete-document", { documentId })
   }
 
+  /**
+   * Imports document binary into the repo.
+   * @param binary - The binary to import
+   */
+  import<T>(binary: Uint8Array) {
+    const doc = Automerge.load<T>(binary)
+
+    const handle = this.create<T>()
+
+    handle.update(() => {
+      return Automerge.clone(doc)
+    })
+
+    return handle
+  }
+
   subscribeToRemotes = (remotes: StorageId[]) => {
     this.#log("subscribeToRemotes", { remotes })
     this.#remoteHeadsSubscriptions.subscribeToRemotes(remotes)

packages/automerge-repo/test/Repo.test.ts

@@ -2,7 +2,7 @@ import { next as A } from "@automerge/automerge"
 import { MessageChannelNetworkAdapter } from "@automerge/automerge-repo-network-messagechannel"
 import assert from "assert"
 import * as Uuid from "uuid"
-import { describe, it } from "vitest"
+import { describe, expect, it } from "vitest"
 import { READY } from "../src/DocHandle.js"
 import { parseAutomergeUrl } from "../src/AutomergeUrl.js"
 import {
@@ -396,6 +396,30 @@ describe("Repo", () => {
       const storageKeyTypes = storageAdapter.keys().map(k => k.split(".")[1])
       assert(storageKeyTypes.filter(k => k === "snapshot").length === 1)
     })
+
+    it("can import an existing document", async () => {
+      const { repo } = setup()
+      const doc = A.init<TestDoc>()
+      const updatedDoc = A.change(doc, d => {
+        d.foo = "bar"
+      })
+
+      const saved = A.save(updatedDoc)
+
+      const handle = repo.import<TestDoc>(saved)
+      assert.equal(handle.isReady(), true)
+      const v = await handle.doc()
+      assert.equal(v?.foo, "bar")
+
+      expect(A.getHistory(v)).toEqual(A.getHistory(updatedDoc))
+    })
+
+    it("throws an error if we try to import an invalid document", async () => {
+      const { repo } = setup()
+      expect(() => {
+        repo.import<TestDoc>(A.init<TestDoc> as unknown as Uint8Array)
+      }).toThrow()
+    })
   })
 
   describe("with peers (linear network)", async () => {