Migration example

examples/__tests__/test-state-migration.ava.js

@@ -0,0 +1,38 @@
+import { Worker } from "near-workspaces";
+import test from "ava";
+
+test.beforeEach(async (t) => {
+    const worker = await Worker.init();
+    const root = worker.rootAccount;
+    const contract = await root.devDeploy("./build/state-migration-original.wasm");
+
+    const ali = await root.createSubAccount("ali");
+
+    t.context.worker = worker;
+    t.context.accounts = { root, contract, ali };
+});
+
+test.afterEach.always(async (t) => {
+    await t.context.worker.tearDown().catch((error) => {
+        console.log("Failed to tear down the worker:", error);
+    });
+});
+
+test("migration works", async (t) => {
+    const { contract, ali } = t.context.accounts;
+
+    await ali.call(contract, "addMessage", { message: { sender: "ali", header: "h1", text: "hello" } });
+    await ali.call(contract, "addMessage", { message: { sender: "ali", header: "h2", text: "world" } });
+    await ali.call(contract, "addMessage", { message: { sender: "ali", header: "h3", text: "This message is too log for new standard" } });
+    await ali.call(contract, "addMessage", { message: { sender: "ali", header: "h4", text: "!" } });
+
+    const res1 = await contract.view("countMessages", {});
+    t.is(res1, 4);
+
+    contract.deploy("./build/state-migration-new.wasm");
+
+    await ali.call(contract, "migrateState", {});
+
+    const res2 = await contract.view("countMessages", {});
+    t.is(res2, 3);
+});

examples/package.json

@@ -25,6 +25,9 @@
     "build:nft-receiver": "near-sdk-js build src/standard-nft/test-token-receiver.ts build/nft-receiver.wasm",
     "build:nft-approval-receiver": "near-sdk-js build src/standard-nft/test-approval-receiver.ts build/nft-approval-receiver.wasm",
     "build:ft": "near-sdk-js build src/standard-ft/my-ft.ts build/my-ft.wasm",
+    "build:state-migration": "run-s build:state-migration:*",
+    "build:state-migration:original": "near-sdk-js build src/state-migration-original.ts build/state-migration-original.wasm",
+    "build:state-migration:new": "near-sdk-js build src/state-migration-new.ts build/state-migration-new.wasm",
     "test": "ava && pnpm test:counter-lowlevel && pnpm test:counter-ts",
     "test:nft": "ava __tests__/standard-nft/*",
     "test:ft": "ava __tests__/standard-ft/*",
@@ -41,6 +44,7 @@
     "test:status-message-collections": "ava __tests__/test-status-message-collections.ava.js",
     "test:parking-lot": "ava __tests__/test-parking-lot.ava.js",
     "test:programmatic-update": "ava __tests__/test-programmatic-update.ava.js",
+    "test:state-migration": "ava __tests__/test-state-migration.ava.js",
     "test:nested-collections": "ava __tests__/test-nested-collections.ava.js"
   },
   "author": "Near Inc <hello@nearprotocol.com>",

examples/src/state-migration-new.ts

@@ -0,0 +1,71 @@
+import { NearBindgen, view, near, migrate, call, Vector, assert } from 'near-sdk-js'
+import { AccountId } from 'near-sdk-js/lib/types'
+
+type OldMessageFormat = {
+    sender: AccountId,
+    header: string,
+    text: string,
+}
+
+// This is the new version of the Message type, it has an additional field
+type NewMessageFormat = {
+    sender: AccountId,
+    recipient?: AccountId,
+    header: string,
+    text: string,
+}
+
+@NearBindgen({})
+export class MigrationDemo {
+    messages: Vector<NewMessageFormat>;
+
+    constructor() {
+        this.messages = new Vector<NewMessageFormat>('messages');
+    }
+
+    @call({ payableFunction: true })
+    addMessage({ message }: {
+        message: NewMessageFormat
+    }): void {
+        this.messages.push(message);
+        near.log(`${near.signerAccountId()} added message ${JSON.stringify(message)}`);
+    }
+
+    @view({})
+    countMessages(): number {
+        return this.messages.toArray().length;
+    }
+
+
+    @migrate({})
+    migrateState(): Vector<NewMessageFormat> {
+        assert(this.messages.toArray().length == 0, "Contract state should not be deserialized in @migrate");
+        // retrieve the current state from the contract
+        let raw_vector = JSON.parse(near.storageRead("STATE")).messages;
+        let old_messages: Vector<OldMessageFormat> = new Vector<OldMessageFormat>(raw_vector.prefix, raw_vector.length);
+        near.log("old_messages: " + JSON.stringify(old_messages));
+
+        // iterate through the state migrating it to the new version
+        let new_messages: Vector<NewMessageFormat> = new Vector('messages');
+
+        for (let old_message of old_messages) {
+            near.log(`migrating ${JSON.stringify(old_message)}`);
+            const new_message: NewMessageFormat = {
+                sender: old_message.sender,
+                recipient: "Unknown",
+                header: old_message.header,
+                text: old_message.text,
+            };
+            if (new_message.text.length < 10) {
+                near.log(`adding ${new_message} to new_messages`);
+                new_messages.push(new_message);
+            } else {
+                near.log(`${new_message} is too long, skipping`);
+            }
+        }
+
+        this.messages = new_messages;
+
+        return this.messages;
+    }
+}

examples/src/state-migration-original.ts

@@ -0,0 +1,30 @@
+import { NearBindgen, view, near, migrate, call, Vector, assert } from 'near-sdk-js'
+import { AccountId } from 'near-sdk-js/lib/types'
+
+type Message = {
+    sender: AccountId,
+    header: string,
+    text: string,
+}
+
+@NearBindgen({})
+export class MigrationDemo {
+    messages: Vector<Message>;
+
+    constructor() {
+        this.messages = new Vector<Message>('messages');
+    }
+
+    @call({ payableFunction: true })
+    addMessage({ message }: {
+        message: Message
+    }): void {
+        this.messages.push(message);
+        near.log(`${near.signerAccountId()} added message ${JSON.stringify(message)}`);
+    }
+
+    @view({})
+    countMessages(): number {
+        return this.messages.toArray().length;
+    }
+}

packages/near-sdk-js/src/cli/build-tools/near-bindgen-exporter.ts

@@ -8,7 +8,7 @@ const { Signale } = signal;
 /**
  * A list of supported method types/decorators.
  */
-const methodTypes = ["call", "view", "initialize"];
+const methodTypes = ["call", "view", "initialize", "migrate"];
 
 /**
  * A helper function that inserts a new throw Error statement with
@@ -34,7 +34,16 @@ function throwError(message: string): t.BlockStatement {
  *
  * @param classId - The class ID of the class which we are extending.
  */
-function readState(classId: t.Identifier): t.VariableDeclaration {
+function readState(classId: t.Identifier, methodType: string): t.VariableDeclaration {
+  if (methodType === "migrate") {
+    return t.variableDeclaration("const", [
+      t.variableDeclarator(
+        t.identifier("_state"),
+        t.nullLiteral()
+      ),
+    ]);
+  }
+
   return t.variableDeclaration("const", [
     t.variableDeclarator(
       t.identifier("_state"),
@@ -216,7 +225,7 @@ function saveToStorage(
   classId: t.Identifier,
   methodType: string
 ): t.EmptyStatement | t.ExpressionStatement {
-  if (!["initialize", "call"].includes(methodType)) {
+  if (!["initialize", "call", "migrate"].includes(methodType)) {
     return t.emptyStatement();
   }
 
@@ -315,7 +324,7 @@ function createDeclaration(
       t.blockStatement([
         // Read the state of the contract from storage.
         // const _state = Contract._getState();
-        readState(classId),
+        readState(classId, methodType),
         // Throw if initialized on any subsequent init function calls.
         // if (_state) { throw new Error('Contract already initialized'); }
         preventDoubleInit(methodType),

packages/near-sdk-js/src/near-bindgen.ts

@@ -10,6 +10,21 @@ type DecoratorFunction = <AnyFunction extends (...args: any) => any>(
   descriptor: TypedPropertyDescriptor<AnyFunction>
 ) => void;
 
+/**
+ * Tells the SDK to use this function as the migration function of the contract.
+ * The migration function will ignore te existing state.
+ * @param _empty - An empty object.
+ */
+export function migrate(_empty: EmptyParameterObject): DecoratorFunction {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  return function <AnyFunction extends (...args: any) => any>(
+    _target: object,
+    _key: string | symbol,
+    _descriptor: TypedPropertyDescriptor<AnyFunction>
+    // eslint-disable-next-line @typescript-eslint/no-empty-function
+  ): void {};
+}
+
 /**
  * Tells the SDK to use this function as the initialization function of the contract.
  *

tests/__tests__/decorators/migrate.ava.js

@@ -0,0 +1,39 @@
+import { Worker } from "near-workspaces";
+import test from "ava";
+
+test.beforeEach(async (t) => {
+  const worker = await Worker.init();
+  const root = worker.rootAccount;
+  const counter = await root.devDeploy("./build/migrate.wasm");
+
+  const ali = await root.createSubAccount("ali");
+
+  t.context.worker = worker;
+  t.context.accounts = { root, counter, ali };
+});
+
+// If the environment is reused, use test.after to replace test.afterEach
+test.afterEach.always(async (t) => {
+  await t.context.worker.tearDown().catch((error) => {
+    console.log("Failed to tear down the worker:", error);
+  });
+});
+
+test("migration works", async (t) => {
+  const { counter, ali } = t.context.accounts;
+
+  const res1 = await counter.view("getCount", {});
+  t.is(res1, 0);
+
+  await ali.call(counter, "increase", {});
+
+  const res2 = await counter.view("getCount", {});
+  t.is(res2, 1);
+
+  const migrationRes = await ali.callRaw(counter, "migrFuncValueTo18", {});
+
+  t.is(JSON.stringify(migrationRes).includes("Count: 0"), true);
+
+  const res3 = await counter.view("getCount", {});
+  t.is(res3, 18);
+});

tests/package.json

@@ -28,6 +28,7 @@
     "build:bigint-serialization": "near-sdk-js build src/bigint-serialization.ts build/bigint-serialization.wasm",
     "build:date-serialization": "near-sdk-js build src/date-serialization.ts build/date-serialization.wasm",
     "build:middlewares": "near-sdk-js build src/middlewares.ts build/middlewares.wasm",
+    "build:migrate": "near-sdk-js build src/migrate.ts build/migrate.wasm",
     "test": "ava",
     "test:context-api": "ava __tests__/test_context_api.ava.js",
     "test:math-api": "ava __tests__/test_math_api.ava.js",
@@ -51,6 +52,7 @@
     "test:date-serialization": "ava __tests__/test-date-serialization.ava.js",
     "test:serialization": "ava __tests__/test-serialization.ava.js",
     "test:constructor-validation": "ava __tests__/constructor_validation.ava.js",
+    "test:migrate": "ava __tests__/decorators/migrate.ava.js",
     "test:middlewares": "ava __tests__/test-middlewares.ava.js"
   },
   "author": "Near Inc <hello@nearprotocol.com>",

tests/src/migrate.ts

@@ -0,0 +1,23 @@
+import { NearBindgen, near, call, view, migrate } from "near-sdk-js";
+
+@NearBindgen({})
+export class Counter {
+    count = 0;
+
+    @call({})
+    increase({ n = 1 }: { n: number }) {
+        this.count += n;
+        near.log(`Counter increased to ${this.count}`);
+    }
+
+    @view({})
+    getCount(): number {
+        return this.count;
+    }
+
+    @migrate({})
+    migrFuncValueTo18(): void {
+        near.log("Count: " + this.count); // expected to be 0
+        this.count = 18;
+    }
+}