Improve ESM support

Author: seppevs

README.md

@@ -263,6 +263,31 @@ $ npm init --yes
 Now you have a package.json file, and you can install your favorite npm modules that might help you in your migration scripts.
 For example, one of the very useful [promise-fun](https://github.com/sindresorhus/promise-fun) npm modules.
 
+
+### Using ESM (ECMAScript Modules) instead of CommonJS
+Since migrate-mongo 7.0.0, it's possible to use ESM instead of CommonJS.
+
+#### Using ESM when initializing a new project
+Pass the `-m esm` option to the `init` action:
+````bash
+$ migrate-mongo init -m esm
+````
+
+It's also required to have package.json file in the root of your project with `"type": "module"`.
+Create a new package.json file:
+````bash
+$ npm init --yes
+````
+
+Then edit this package.json file, and add:
+````bash
+"type": "module"
+````
+
+When you create migration files with `migrate-mongo create`, they will be prepared for you in ESM style.
+
+Please note that CommonJS is still the default module loading system.
+
 ### Using MongoDB's Transactions API
 You can make use of the [MongoDB Transaction API](https://docs.mongodb.com/manual/core/transactions/) in your migration scripts.
 

bin/migrate-mongo.js

@@ -32,7 +32,9 @@ program.version(pkgjson.version);
 program
   .command("init")
   .description("initialize a new migration project")
-  .action(() =>
+  .option("-m --module <module loading system>", "module loading system (commonjs (DEFAULT) or esm)")
+  .action(options => {
+    global.options = options;
     migrateMongo
       .init()
       .then(() =>
@@ -41,7 +43,7 @@ program
         )
       )
       .catch(err => handleError(err))
-  );
+  });
 
 program
   .command("create [description]")

lib/actions/create.js

@@ -2,6 +2,7 @@ const fs = require("fs-extra");
 const path = require("path");
 const date = require("../utils/date");
 const migrationsDir = require("../env/migrationsDir");
+const config = require("../env/config");
 
 module.exports = async description => {
   if (!description) {
@@ -16,7 +17,8 @@ module.exports = async description => {
   if (await migrationsDir.doesSampleMigrationExist()) {
     source = await migrationsDir.resolveSampleMigrationPath();
   } else {
-    source = path.join(__dirname, "../../samples/migration.js");
+    const configContent = await config.read();
+    source = path.join(__dirname, `../../samples/${configContent.moduleSystem}/migration.js`);
   }
 
   const filename = `${date.nowAsString()}-${description

lib/actions/init.js

@@ -5,7 +5,8 @@ const migrationsDir = require("../env/migrationsDir");
 const config = require("../env/config");
 
 function copySampleConfigFile() {
-  const source = path.join(__dirname, "../../samples/migrate-mongo-config.js");
+  const moduleSystem = global.options.module === 'esm' ? 'esm' : 'commonjs';
+  const source = path.join(__dirname, `../../samples/${moduleSystem}/migrate-mongo-config.js`);
   const destination = path.join(
     process.cwd(),
     config.DEFAULT_CONFIG_FILE_NAME

samples/migrate-mongo-config.js renamed to samples/commonjs/migrate-mongo-config.js

@@ -27,8 +27,10 @@ const config = {
 
   // Enable the algorithm to create a checksum of the file contents and use that in the comparison to determin
   // if the file should be run.  Requires that scripts are coded to be run multiple times.
-  useFileHash: false
+  useFileHash: false,
+
+  // Don't change this, unless you know what you're doing
+  moduleSystem: 'commonjs',
 };
 
-// Return the config as a promise
 module.exports = config;

samples/migration.js renamed to samples/commonjs/migration.js

@@ -0,0 +1,36 @@
+// In this file you can configure migrate-mongo
+
+const config = {
+    mongodb: {
+        // TODO Change (or review) the url to your MongoDB:
+        url: "mongodb://localhost:27017",
+
+        // TODO Change this to your database name:
+        databaseName: "YOURDATABASENAME",
+
+        options: {
+            useNewUrlParser: true, // removes a deprecation warning when connecting
+            useUnifiedTopology: true, // removes a deprecating warning when connecting
+            //   connectTimeoutMS: 3600000, // increase connection timeout to 1 hour
+            //   socketTimeoutMS: 3600000, // increase socket timeout to 1 hour
+        }
+    },
+
+    // The migrations dir, can be an relative or absolute path. Only edit this when really necessary.
+    migrationsDir: "migrations",
+
+    // The mongodb collection where the applied changes are stored. Only edit this when really necessary.
+    changelogCollectionName: "changelog",
+
+    // The file extension to create migrations and search for in migration dir
+    migrationFileExtension: ".js",
+
+    // Enable the algorithm to create a checksum of the file contents and use that in the comparison to determin
+    // if the file should be run.  Requires that scripts are coded to be run multiple times.
+    useFileHash: false,
+
+    // Don't change this, unless you know what you're doing
+    moduleSystem: 'esm',
+};
+
+export default config;

samples/esm/migrate-mongo-config.js

@@ -0,0 +1,12 @@
+export const up = async (db, client) => {
+    // TODO write your migration here.
+    // See https://github.com/seppevs/migrate-mongo/#creating-a-new-migration-script
+    // Example:
+    // await db.collection('albums').updateOne({artist: 'The Beatles'}, {$set: {blacklisted: true}});
+};
+
+export const down = async (db, client) => {
+    // TODO write the statements to rollback your migration (if possible)
+    // Example:
+    // await db.collection('albums').updateOne({artist: 'The Beatles'}, {$set: {blacklisted: false}});
+};

samples/esm/migration.js

@@ -21,6 +21,9 @@ describe("create", () => {
   function mockConfig() {
     return {
       shouldExist: sinon.stub().returns(Promise.resolve()),
+      read: sinon.stub().returns(Promise.resolve({
+        moduleSystem: 'commonjs',
+      }))
     };
   }
 
@@ -79,7 +82,7 @@ describe("create", () => {
     const filename = await create("my_description");
     expect(fs.copy.called).to.equal(true);
     expect(fs.copy.getCall(0).args[0]).to.equal(
-      path.join(__dirname, "../../samples/migration.js")
+      path.join(__dirname, "../../samples/commonjs/migration.js")
     );
     expect(fs.copy.getCall(0).args[1]).to.equal(
       path.join(process.cwd(), "migrations", "20160609080700-my_description.js")
@@ -96,7 +99,7 @@ describe("create", () => {
     const filename = await create("my_description");
     expect(fs.copy.called).to.equal(true);
     expect(fs.copy.getCall(0).args[0]).to.equal(
-      path.join(__dirname, "../../samples/migration.js")
+      path.join(__dirname, "../../samples/commonjs/migration.js")
     );
     expect(fs.copy.getCall(0).args[1]).to.equal(
       path.join(process.cwd(), "migrations", "20160609080700-my_description.ts")
@@ -112,7 +115,7 @@ describe("create", () => {
     await create("this description contains spaces");
     expect(fs.copy.called).to.equal(true);
     expect(fs.copy.getCall(0).args[0]).to.equal(
-      path.join(__dirname, "../../samples/migration.js")
+      path.join(__dirname, "../../samples/commonjs/migration.js")
     );
     expect(fs.copy.getCall(0).args[1]).to.equal(
       path.join(

test/actions/create.test.js

@@ -29,6 +29,7 @@ describe("init", () => {
   }
 
   beforeEach(() => {
+    global.options = { module: 'commonjs' };
     migrationsDir = mockMigrationsDir();
     config = mockConfig();
     fs = mockFs();
@@ -82,7 +83,7 @@ describe("init", () => {
 
     const source = fs.copy.getCall(0).args[0];
     expect(source).to.equal(
-      path.join(__dirname, "../../samples/migrate-mongo-config.js")
+      path.join(__dirname, "../../samples/commonjs/migrate-mongo-config.js")
     );
 
     const destination = fs.copy.getCall(0).args[1];