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. _{10.x and above were not tested at all}
esbuild 0.15.x

Problems

https://github.com/nestjs/nest-cli/issues/1157 https://github.com/nestjs/swagger/issues/1450 https://github.com/evanw/esbuild/pull/509 https://github.com/evanw/esbuild/issues/566

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);

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 } };
  }
}

NodeJS builtins are referenced via require API.

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

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

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

_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 } }
  }
};

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