RFC: use LB3 models in an LB4 app [SPIKE - DO NOT MERGE]

SPIKE-NOTES.md

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+## Open questions
+
+- How to test code migrated from strong-remoting and loopback (v3)? Do we want
+  to copy existing tests over? Migrate them to async/await style? Don't bother
+  with testing at all, use few acceptance-level tests only?
+
+- How to split 2k+ lines of new (migrated) code into smaller chunks that will be
+  easier to review?
+
+- Should we register LB3 Models for dependency injection into LB4 code? Register
+  them as repositories, models, services, or something else?
+
+- Should we implement booting datasources from `datasources.json`? I see two
+  obstacles:
+
+  1. Datasources must be booted before models are attached.
+  2. LB3 supports variable replacement in JSON config files using ENV vars but
+     also `app.get(name)`. This may add unwanted complexity to our compat layer.
+
+## By the way
+
+- TypeScript does not support static index signature, which make it difficult to
+  consume custom model methods. See
+  https://github.com/Microsoft/TypeScript/issues/6480.
+
+- I'd like us to extract the Booter contract into a standalone package so that
+  v3compat and other similar extensions don't have to inherit entire boot and
+  don't have to lock down a specific semver-major version of boot in extension
+  dependencies. Instead, they should depend on the Booter contract only, this
+  contract should not be changed so often (hopefully).

examples/lb3models/LICENSE

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+Copyright (c) IBM Corp. 2017,2018. All Rights Reserved.
+Node module: @loopback/lb3models
+This project is licensed under the MIT License, full text below.
+
+--------
+
+MIT license
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

examples/lb3models/README.md

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+# @loopback/example-lb3models
+
+This project demonstrates how to add LoopBack 3 models into a LoopBack 4
+application.
+
+## Instructions
+
+1. Create a new LB4 app using `lb4 app`. Add `@loopback/v3compat'` to project
+   dependencies.
+
+2. Copy your model files from `common/models` to `legacy/models` directory, for
+   example:
+
+   ```text
+   legacy/models/coffee-shop.js
+   legacy/models/coffee-shop.json
+   ```
+
+   IMPORTANT! These files must live outside your `src` directory, out of sight
+   of TypeScript compiler.
+
+3. Copy your `server/model-config` to `src/legacy/model-config.json`.
+
+   Remove references to LoopBack 3 built-in models like User and ACL. LoopBack 4
+   does not support local authentication yet.
+
+   Remove `_meta` section, LoopBack 4 does not support this config option.
+
+4. Modify your Application class and apply `CompatMixin`.
+
+   ```ts
+   import {CompatMixin} from '@loopback/v3compat';
+   // ...
+
+   export class TodoListApplication extends CompatMixin(
+     BootMixin(ServiceMixin(RepositoryMixin(RestApplication))),
+   ) {
+     // ...
+   }
+   ```
+
+5. Register your legacy datasources in Application's constructor.
+
+   ```ts
+   this.v3compat.dataSource('mysqlDs', {
+     name: 'mysqlDs',
+     connector: 'mysql',
+     host: 'demo.strongloop.com',
+     port: 3306,
+     database: 'getting_started',
+     username: 'demo',
+     password: 'L00pBack',
+   });
+   ```
+
+## Need help?
+
+Check out our [Gitter channel](https://gitter.im/strongloop/loopback) and ask
+for help with this tutorial.
+
+## Bugs/Feedback
+
+Open an issue in [loopback-next](https://github.com/strongloop/loopback-next)
+and we'll take a look.
+
+## Contributions
+
+- [Guidelines](https://github.com/strongloop/loopback-next/blob/master/docs/CONTRIBUTING.md)
+- [Join the team](https://github.com/strongloop/loopback-next/issues/110)
+
+## Tests
+
+Run `npm test` from the root folder.
+
+## Contributors
+
+See
+[all contributors](https://github.com/strongloop/loopback-next/graphs/contributors).
+
+## License
+
+MIT

examples/lb3models/index.d.ts

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+// Copyright IBM Corp. 2017,2018. All Rights Reserved.
+// Node module: @loopback/example-lb3models
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+export * from './dist';

examples/lb3models/index.js

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+// Copyright IBM Corp. 2017,2018. All Rights Reserved.
+// Node module: @loopback/example-lb3models
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+const application = require('./dist');
+
+module.exports = application;
+
+if (require.main === module) {
+  // Run the application
+  const config = {
+    rest: {
+      port: +process.env.PORT || 3000,
+      host: process.env.HOST || 'localhost',
+      openApiSpec: {
+        // useful when used with OASGraph to locate your application
+        setServersFromRequest: true,
+      },
+    },
+  };
+  application.main(config).catch(err => {
+    console.error('Cannot start the application.', err);
+    process.exit(1);
+  });
+}

examples/lb3models/index.ts

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+// Copyright IBM Corp. 2017,2018. All Rights Reserved.
+// Node module: @loopback/example-lb3models
+// This file is licensed under the MIT License.
+// License text available at https://opensource.org/licenses/MIT
+
+// DO NOT EDIT THIS FILE
+// Add any additional (re)exports to src/index.ts instead.
+export * from './src';

examples/lb3models/legacy/model-config.json

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+{
+  "CoffeeShop": {
+    "dataSource": "mysqlDs",
+    "public": true
+  }
+}

examples/lb3models/legacy/models/coffee-shop.js

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+'use strict';
+
+module.exports = function(CoffeeShop) {
+  CoffeeShop.status = function(cb) {
+    var currentDate = new Date();
+    var currentHour = currentDate.getHours();
+    var OPEN_HOUR = 6;
+    var CLOSE_HOUR = 20;
+    console.log('Current hour is %d', currentHour);
+    var response;
+    if (currentHour > OPEN_HOUR && currentHour < CLOSE_HOUR) {
+      response = 'We are open for business.';
+    } else {
+      response = 'Sorry, we are closed. Open daily from 6am to 8pm.';
+    }
+    cb(null, response);
+  };
+  CoffeeShop.remoteMethod('status', {
+    http: {
+      path: '/status',
+      verb: 'get',
+    },
+    returns: {
+      arg: 'status',
+      type: 'string',
+    },
+  });
+};

examples/lb3models/legacy/models/coffee-shop.json

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+{
+  "name": "CoffeeShop",
+  "base": "PersistedModel",
+  "idInjection": true,
+  "forceId": false,
+  "options": {
+    "validateUpsert": true
+  },
+  "properties": {
+    "name": {
+      "type": "string",
+      "required": true
+    },
+    "city": {
+      "type": "string"
+    }
+  },
+  "validations": [],
+  "relations": {},
+  "acls": [],
+  "methods": {}
+}

examples/lb3models/package.json

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+{
+  "name": "@loopback/example-lb3models",
+  "version": "0.1.0",
+  "description": "An example on how to add LoopBack 3 models into a LoopBack 4 application.",
+  "main": "index.js",
+  "engines": {
+    "node": ">=8.9"
+  },
+  "scripts": {
+    "build:apidocs": "lb-apidocs",
+    "build": "lb-tsc es2017 --outDir dist",
+    "build:watch": "lb-tsc es2017 --outDir dist --watch",
+    "clean": "lb-clean *example-lb3models*.tgz dist package api-docs",
+    "lint": "npm run prettier:check && npm run tslint",
+    "lint:fix": "npm run tslint:fix && npm run prettier:fix",
+    "prettier:cli": "lb-prettier \"**/*.ts\"",
+    "prettier:check": "npm run prettier:cli -- -l",
+    "prettier:fix": "npm run prettier:cli -- --write",
+    "tslint": "lb-tslint",
+    "tslint:fix": "npm run tslint -- --fix",
+    "pretest": "npm run build",
+    "test": "lb-mocha \"dist/test/*/**/*.js\"",
+    "test:dev": "lb-mocha --allow-console-logs dist/test/**/*.js && npm run posttest",
+    "verify": "npm pack && tar xf loopback-todo*.tgz && tree package && npm run clean",
+    "migrate": "node ./dist/src/migrate",
+    "prestart": "npm run build",
+    "start": "node ."
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/strongloop/loopback-next.git"
+  },
+  "publishConfig": {
+    "access": "public"
+  },
+  "license": "MIT",
+  "dependencies": {
+    "@loopback/boot": "^1.0.10",
+    "@loopback/context": "^1.4.1",
+    "@loopback/core": "^1.1.4",
+    "@loopback/rest": "^1.5.3",
+    "@loopback/rest-explorer": "^1.1.6",
+    "@loopback/v3compat": "^0.1.0",
+    "loopback-connector-mysql": "^5.3.1"
+  },
+  "devDependencies": {
+    "@loopback/build": "^1.2.0",
+    "@loopback/testlab": "^1.0.4",
+    "@loopback/tslint-config": "^2.0.0",
+    "@types/lodash": "^4.14.109",
+    "@types/node": "^10.11.2",
+    "lodash": "^4.17.10",
+    "tslint": "^5.12.0",
+    "typescript": "^3.2.2"
+  },
+  "keywords": [
+    "loopback",
+    "LoopBack",
+    "example",
+    "tutorial",
+    "CRUD",
+    "models",
+    "todo"
+  ]
+}

examples/lb3models/public/index.html

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+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+  <title>@loopback/example-lb3models</title>
+
+  <meta charset="utf-8">
+  <meta http-equiv="X-UA-Compatible" content="IE=edge">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <link rel="shortcut icon" type="image/x-icon" href="//v4.loopback.io/favicon.ico">
+
+  <style>
+    h3 {
+      margin-left: 25px;
+      text-align: center;
+    }
+
+    a, a:visited {
+      color: #3f5dff;
+    }
+
+    h3 a {
+      margin-left: 10px;
+    }
+
+    a:hover, a:focus, a:active {
+      color: #001956;
+    }
+
+    .power {
+      position: absolute;
+      bottom: 25px;
+      left: 50%;
+      transform: translateX(-50%);
+    }
+
+    .info {
+      position: absolute;
+      top: 50%;
+      left: 50%;
+      transform: translate(-50%, -50%)
+    }
+
+    .info h1 {
+      text-align: center;
+      margin-bottom: 0
+    }
+
+    .info p {
+      text-align: center;
+      margin-bottom: 3em;
+      margin-top: 1em;
+    }
+  </style>
+</head>
+
+<body>
+  <div class="info">
+    <h1>@loopback/example-lb3models</h1>
+
+    <h3>OpenAPI spec: <a href="/openapi.json">/openapi.json</a></h3>
+    <h3>API Explorer: <a href="/explorer">/explorer</a></h3>
+  </div>
+
+  <footer class="power">
+    <a href="https://v4.loopback.io" target="_blank">
+      <img src="https://loopback.io/images/branding/powered-by-loopback/blue/powered-by-loopback-sm.png" />
+    </a>
+  </footer>
+</body>
+
+</html>
+