nestjs-esm-fix

Patch Nestjs app ESM bundles to make them work RHRN
⚠️ This is a temporary solution until Nestjs is fixed

Stack

• Nestjs 9.x
• esbuild 0.15.x

Problems

https://github.com/nestjs/nest-cli/issues/1157 https://github.com/evanw/esbuild/pull/509 https://github.com/evanw/esbuild/issues/566

1. openapi is not defined. https://github.com/nestjs/swagger/issues/1450

__decorate([
  Post('event-unsafe-batch'),
  HttpCode(200),
  openapi.ApiResponse({ status: 200, type: String }),
  __param(0, Body()),
  __param(1, Req()),
  __metadata("design:type", Function),
  __metadata("design:paramtypes", [Object, Object]),
  __metadata("design:returntype", Promise)
], EventUnsafeController.prototype, "logEventBatch", null);

2. openapi / class-validator DTOs are referenced by require API. https://github.com/microsoft/TypeScript/issues/43329

export class CspReportDto {
  static _OPENAPI_METADATA_FACTORY() {
    return { timestamp: { required: false, type: () => Object }, 'csp-report': { required: true, type: () => require("./csp.dto.js").CspReport } };
  }
}

3. NodeJS builtins are referenced via require API.

var require_async4 = __commonJS({
  "node_modules/resolve/lib/async.js"(exports, module2) {
    var fs2 = require("fs");

4. esbuild-compiled ESM bundle cannot refer to views/redoc.handlebars

const redocFilePath = path_1.default.join(__dirname, "..", "views", "redoc.handlebars");

5. _OPENAPI_METADATA_FACTORY class fields may be empty, so the swagger declaration cannot be properly rendered.

var Meta = class {
};
// →
var Meta = class {
  static _OPENAPI_METADATA_FACTORY() {
    return { appName: { required: false,  type: () =>  String }, appHost: { required: false,  type: () =>  String }, appVersion: { required: false,  type: () =>  String }, appNamespace: { required: false,  type: () =>  String }, appConfig: { required: false,  type: () =>  typeof (_a3 = typeof Record !== "undefined" && Record) === "function" ? _a3 : Object }, deviceInfo: { required: false,  type: () =>  typeof (_b3 = typeof Record !== "undefined" && Record) === "function" ? _b3 : Object }, userAgent: { required: false,  type: () =>  String }, envProfile: { required: false,  enum:  typeof (_c = typeof import_substrate2.EnvironmentProfile !== "undefined" && import_substrate2.EnvironmentProfile) === "function" ? _c : Object } }
  }
};

6. Extra type wrappers cannot be processed by openapi / class-validator / class-transformer

  __metadata("design:type", typeof (_d = typeof Array !== "undefined" && Array) === "function" ? _d : Object)
  __metadata("design:type", typeof (_e = typeof import_substrate2.LogLevel !== "undefined" && import_substrate2.LogLevel) === "function" ? _e : Object)
  // →
  __metadata("design:type", Array)
  __metadata("design:type", import_substrate2.LogLevel)

Solution

Old good monkey patching.

Install

yarn add -D nestjs-esm-fix

Usage

CLI

nestjs-esm-fix target/**/*.js
nestjs-esm-fix --target=target/**/*.js
nestjs-esm-fix --target=**/* --cwd=target

| Option | Description | Default | |---------------------------|------------------------------------------------------------------------------------------------------------------------|-----------------| | --target | Pattern to match files to fix. | **/* | | --cwd | Current working dir. | process.cwd() | | --openapi-complex-types | Simplify __metadata("design:type") declarations. | true | | --openapi-meta | Restore static OPENAPI_METADATA_FACTORY if missing. | true | | --openapi-var | Inject openapi variable. Set --no-openapi-var to disable. | true | | --dirname-var | Inject __dirname and __filename polyfills. | true | | --importify | Replace require with import API for Nodejs builtins. Replace type: () => require(smth) statements with import. | true | | --require-main | Inject main field for require API polyfill. | true | | --redoc-tpl | Inject redoc.hbs templates. | true |

JS API

import { fix } from 'nestjs-esm-fix'
await fix({
  cwd: '.',
  target: 'target/**/*.js',
  openapiComplexTypes: true,
  openapiVar: true,
  openapiMeta: true,
  dirnameVar: true,
  importify: true,
  requireMain: true,
  redocTpl: true
})

License

MIT