Merge pull request #4 from leonardfactory/inversifyjs-property-injector

Support InversifyJS property injection

Author: leonardfactory

.gitignore

@@ -7,6 +7,7 @@ yarn-error.log*
 
 # Emit
 lib
+examples/**/lib
 
 # Runtime data
 pids

.vscode/launch.json

@@ -0,0 +1,14 @@
+{
+  // Usare IntelliSense per informazioni sui possibili attributi.
+  // Al passaggio del mouse vengono visualizzate le descrizioni degli attributi esistenti.
+  // Per ulteriori informazioni, visitare: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "type": "node",
+      "request": "attach",
+      "name": "Attach",
+      "port": 9229
+    }
+  ]
+}

README.md

@@ -106,6 +106,37 @@ With `.babelrc`:
 }
 ```
 
+### Usage with [InversifyJS](http://inversify.io)
+
+If you are using normal dependency injection letting Inversify **create your instances**, you should be fine with all kind of decorators.
+
+Instead, if you are using **property injection**, when [the container does not
+create the instances](https://github.com/inversify/InversifyJS/blob/master/wiki/property_injection.md#when-we-cannot-use-inversifyjs-to-create-an-instance-of-a-class),
+you would likely encounter errors since babel
+decorators are not exactly the same as TypeScript.
+
+You can fix it by _enhancing property decorators_ with the following function:
+
+```ts
+import getDecorators from 'inversify-inject-decorators';
+// setup the container...
+let { lazyInject: originalLazyInject } = getDecorators(container);
+
+// Additional function to make properties decorators compatible with babel.
+function fixPropertyDecorator<T extends Function>(decorator: T): T {
+  return ((...args: any[]) => (
+    target: any,
+    propertyName: any,
+    ...decoratorArgs: any[]
+  ) => {
+    decorator(...args)(target, propertyName, ...decoratorArgs);
+    return Object.getOwnPropertyDescriptor(target, propertyName);
+  }) as any;
+}
+
+export const lazyInject = fixPropertyDecorator(originalLazyInject);
+```
+
 ## Current Pitfalls
 
 - We cannot know if type annotations are just types (i.e. `IMyInterface`) or

examples/inversify/.babelrc

@@ -0,0 +1,11 @@
+{
+  "plugins": [
+    "../../lib/plugin.js",
+    ["@babel/plugin-proposal-decorators", { "legacy": true }],
+    ["@babel/plugin-proposal-class-properties", { "loose": true }]
+  ],
+  "presets": [
+    ["@babel/preset-env", { "targets": { "node": "current" } }],
+    "@babel/preset-typescript"
+  ]
+}

examples/inversify/package.json

@@ -0,0 +1,26 @@
+{
+  "name": "inversify",
+  "version": "0.0.1",
+  "main": "index.js",
+  "license": "MIT",
+  "private": true,
+  "scripts": {
+    "build": "babel src -d lib -x '.ts,.tsx'",
+    "dev": "babel src -w -d lib -x '.ts,.tsx'",
+    "start": "node lib/index.js"
+  },
+  "devDependencies": {
+    "@babel/cli": "^7.2.3",
+    "@babel/core": "^7.4.0",
+    "@babel/plugin-proposal-class-properties": "^7.4.0",
+    "@babel/plugin-proposal-decorators": "^7.4.0",
+    "@babel/preset-env": "^7.4.2",
+    "@babel/preset-typescript": "^7.3.3",
+    "typescript": "^3.3.4000"
+  },
+  "dependencies": {
+    "inversify": "^5.0.1",
+    "inversify-inject-decorators": "^3.1.0",
+    "reflect-metadata": "^0.1.13"
+  }
+}

examples/inversify/src/index.ts

@@ -0,0 +1,46 @@
+import 'reflect-metadata';
+
+import getDecorators from 'inversify-inject-decorators';
+import { Container, injectable } from 'inversify';
+
+@injectable()
+class PrintService {
+  print(book: Book) {
+    console.log(`Book "${book.summary}" by ${book.author}.`);
+  }
+}
+
+let container = new Container();
+container.bind<PrintService>('PrintService').to(PrintService);
+let { lazyInject } = getDecorators(container);
+
+/**
+ * Additional function to make properties decorators compatible with babel.
+ */
+function fixPropertyDecorator<T extends Function>(decorator: T): T {
+  return ((...args: any[]) => (
+    target: any,
+    propertyName: any,
+    ...decoratorArgs: any[]
+  ) => {
+    decorator(...args)(target, propertyName, ...decoratorArgs);
+    return Object.getOwnPropertyDescriptor(target, propertyName);
+  }) as any;
+}
+
+const lazyInjectFix = fixPropertyDecorator(lazyInject);
+
+class Book {
+  @lazyInjectFix('PrintService')
+  private printService!: PrintService;
+
+  public constructor(public author: string, public summary: string) {}
+
+  public print() {
+    this.printService.print(this);
+  }
+}
+
+// Book instance is NOT created by InversifyJS
+let book = new Book('George Orwell', '1984');
+book.print();

examples/inversify/tsconfig.json

@@ -0,0 +1,17 @@
+{
+  "compilerOptions": {
+    "target": "esnext",
+    "module": "commonjs",
+    "strict": true,
+    "allowSyntheticDefaultImports": true,
+    "esModuleInterop": true,
+
+    "experimentalDecorators": true,
+    "emitDecoratorMetadata": true,
+
+    "outDir": "lib",
+    "rootDir": "src",
+    "baseUrl": "."
+  },
+  "include": ["src/index.ts"]
+}