feat(transactional-adapter-mongoose): add mongoose adapter (#159)

* feat(transactional-adapter-mongoose): add `mongoose` adapter

* docs(transactional-adapter-mongoose): add docs

docs/docs/06_plugins/01_available-plugins/01-transactional/07-mongoose-adapter.md

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+import Tabs from '@theme/Tabs';
+import TabItem from '@theme/TabItem';
+
+# Mongoose adapter
+
+## Installation
+
+<Tabs>
+<TabItem value="npm" label="npm" default>
+
+```bash
+npm install @nestjs-cls/transactional-adapter-mongoose
+```
+
+</TabItem>
+<TabItem value="yarn" label="yarn">
+
+```bash
+yarn add @nestjs-cls/transactional-adapter-mongoose
+```
+
+</TabItem>
+<TabItem value="pnpm" label="pnpm">
+
+```bash
+pnpm add @nestjs-cls/transactional-adapter-mongoose
+```
+
+</TabItem>
+</Tabs>
+
+## Registration
+
+```ts
+ClsModule.forRoot({
+    plugins: [
+        new ClsPluginTransactional({
+            imports: [
+                // module in which the Connection instance is provided
+                MongooseModule,
+            ],
+            adapter: new TransactionalAdapterMongoose({
+                // the injection token of the mongoose Connection
+                mongooseConnectionToken: Connection,
+            }),
+        }),
+    ],
+});
+```
+
+## Typing & usage
+
+To work correctly, the adapter needs to inject an instance of mongoose [`Connection`](<https://mongoosejs.com/docs/api/connection.html#Connection()>).
+
+Due to how transactions work in MongoDB, [and in turn in Mongoose](https://mongoosejs.com/docs/transactions.html), the usage of the Mongoose adapter is a bit different from the others.
+
+The `tx` property on the `TransactionHost<TransactionalAdapterMongoose>` does _not_ refer to any _transactional_ instance, but rather to a [`ClientSession`](https://mongodb.github.io/node-mongodb-native/6.7/classes/ClientSession.html) instance of `mongodb`, with an active transaction, or `null` when no transaction is active.
+
+Queries are not executed using the `ClientSession` instance, but instead the `ClientSession` instance or `null` is passed to the query as the `session` option.
+
+:::important
+
+The `TransactionalAdapterMongoose` _does not support_ the ["Transaction Proxy"](./index.md#using-the-injecttransaction-decorator) feature, because proxying a `null` value is not supported by the JavaScript Proxy.
+
+::::
+
+## Example
+
+```ts title="database.schemas.ts"
+const userSchema = new Schema({
+    name: String,
+    email: String,
+});
+
+const User = mongoose.model('user', userSchema);
+```
+
+```ts title="user.service.ts"
+@Injectable()
+class UserService {
+    constructor(private readonly userRepository: UserRepository) {}
+
+    @Transactional()
+    async runTransaction() {
+        // highlight-start
+        // both methods are executed in the same transaction
+        const user = await this.userRepository.createUser('John');
+        const foundUser = await this.userRepository.getUserById(user._id);
+        // highlight-end
+        assert(foundUser._id === user._id);
+    }
+}
+```
+
+```ts title="user.repository.ts"
+@Injectable()
+class UserRepository {
+    constructor(
+        private readonly txHost: TransactionHost<TransactionalAdapterMongoose>,
+    ) {}
+
+    async getUserById(id: ObjectId) {
+        // txHost.tx is typed as ClientSession
+        return await User.findById(id)
+            // highlight-start
+            .session(this.txHost.tx);
+        // highlight-end
+    }
+
+    async createUser(name: string) {
+        const user = new User({ name: name, email: `${name}@email.com` });
+        await user
+            // highlight-start
+            .save({ session: this.txHost.tx });
+        // highlight-end
+        return user;
+    }
+}
+```
+
+## Considerations
+
+### Using with built-in Mongoose AsyncLocalStorage support
+
+Mongoose > 8.4 has a built-in support for [propagating the `session` via `AsyncLocalStorage`](https://mongoosejs.com/docs/transactions.html#asynclocalstorage).
+
+The feature is compatible with `@nestjs-cls/transactional` and when enabled, one _does not_ have to pass `TransactionHost#tx` to queries and still enjoy the simplicity of the `@Transactional` decorator, which starts and ends the underlying transaction automatically.
+
+**However**, because `@nestjs-cls/transactional` has no control over the propagation of the `session` instance via Mongoose's `AsyncLocalStorage`,
+there is **no implicit support for opting out of an ongoing transaction** via `TransactionHost#withoutTransaction` (or analogously the [`Propagation.NotSupported`](./index.md#transaction-propagation) mode).
+
+To opt out of an ongoing transaction, you have to explicitly pass `null` to the `session` option when calling the query. Alternatively, you can explicitly pass in the value of `TransactionHost#tx` if the query should support both transactional and non-transactional mode and you want to control it using `Propagation`.

packages/transactional-adapters/transactional-adapter-mongoose/README.md

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+# @nestjs-cls/transactional-adapter-knex
+
+Mongoose adapter for the `@nestjs-cls/transactional` plugin.
+
+### ➡️ [Go to the documentation website](https://papooch.github.io/nestjs-cls/plugins/available-plugins/transactional/mongoose-adapter) 📖

packages/transactional-adapters/transactional-adapter-mongoose/jest.config.js

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+module.exports = {
+    moduleFileExtensions: ['js', 'json', 'ts'],
+    rootDir: '.',
+    testRegex: '.*\\.spec\\.ts$',
+    transform: {
+        '^.+\\.ts$': [
+            'ts-jest',
+            {
+                isolatedModules: true,
+                maxWorkers: 1,
+            },
+        ],
+    },
+    collectCoverageFrom: ['src/**/*.ts'],
+    coverageDirectory: '../coverage',
+    testEnvironment: 'node',
+};

packages/transactional-adapters/transactional-adapter-mongoose/package.json

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+{
+    "name": "@nestjs-cls/transactional-adapter-mongoose",
+    "version": "1.0.0",
+    "description": "A mongoose adapter for @nestjs-cls/transactional",
+    "author": "papooch",
+    "license": "MIT",
+    "engines": {
+        "node": ">=18"
+    },
+    "publishConfig": {
+        "access": "public"
+    },
+    "repository": {
+        "type": "git",
+        "url": "git+https://github.com/Papooch/nestjs-cls.git"
+    },
+    "homepage": "https://papooch.github.io/nestjs-cls/",
+    "keywords": [
+        "nest",
+        "nestjs",
+        "cls",
+        "continuation-local-storage",
+        "als",
+        "AsyncLocalStorage",
+        "async_hooks",
+        "request context",
+        "async context",
+        "transaction",
+        "transactional",
+        "transactional decorator",
+        "aop",
+        "mongoose"
+    ],
+    "main": "dist/src/index.js",
+    "types": "dist/src/index.d.ts",
+    "files": [
+        "dist/src/**/!(*.spec).d.ts",
+        "dist/src/**/!(*.spec).js"
+    ],
+    "scripts": {
+        "prepack": "cp ../../../LICENSE ./LICENSE",
+        "prebuild": "rimraf dist",
+        "build": "tsc",
+        "test": "jest",
+        "test:watch": "jest --watch",
+        "test:cov": "jest --coverage"
+    },
+    "peerDependencies": {
+        "@nestjs-cls/transactional": "workspace:^2.2.2",
+        "mongoose": "> 8",
+        "nestjs-cls": "workspace:^4.3.0"
+    },
+    "devDependencies": {
+        "@nestjs/cli": "^10.0.2",
+        "@nestjs/common": "^10.3.7",
+        "@nestjs/core": "^10.3.7",
+        "@nestjs/testing": "^10.3.7",
+        "@types/jest": "^28.1.2",
+        "@types/node": "^18.0.0",
+        "jest": "^29.7.0",
+        "mongodb-memory-server": "^9.4.0",
+        "mongoose": "^8.4.4",
+        "reflect-metadata": "^0.1.13",
+        "rimraf": "^3.0.2",
+        "rxjs": "^7.5.5",
+        "sqlite3": "^5.1.7",
+        "ts-jest": "^29.1.2",
+        "ts-loader": "^9.3.0",
+        "ts-node": "^10.8.1",
+        "tsconfig-paths": "^4.0.0",
+        "typescript": "5.0"
+    }
+}

packages/transactional-adapters/transactional-adapter-mongoose/src/index.ts

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+export * from './lib/transactional-adapter-mongoose';

packages/transactional-adapters/transactional-adapter-mongoose/src/lib/transactional-adapter-mongoose.ts

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+import { TransactionalAdapter } from '@nestjs-cls/transactional';
+import { ClientSession, Connection } from 'mongoose';
+
+type MongooseTransactionOptions = Parameters<Connection['transaction']>[1];
+
+export interface MongoDBTransactionalAdapterOptions {
+    /**
+     * The injection token for the mongoose Connection instance.
+     */
+    mongooseConnectionToken: any;
+
+    /**
+     * Default options for the transaction. These will be merged with any transaction-specific options
+     * passed to the `@Transactional` decorator or the `TransactionHost#withTransaction` method.
+     */
+    defaultTxOptions?: Partial<MongooseTransactionOptions>;
+}
+
+export class TransactionalAdapterMongoose
+    implements
+        TransactionalAdapter<
+            Connection,
+            ClientSession | null,
+            MongooseTransactionOptions
+        >
+{
+    connectionToken: any;
+
+    defaultTxOptions?: Partial<MongooseTransactionOptions>;
+
+    constructor(options: MongoDBTransactionalAdapterOptions) {
+        this.connectionToken = options.mongooseConnectionToken;
+        this.defaultTxOptions = options.defaultTxOptions;
+    }
+
+    supportsTransactionProxy = false;
+
+    optionsFactory(connection: Connection) {
+        return {
+            wrapWithTransaction: async (
+                options: MongooseTransactionOptions,
+                fn: (...args: any[]) => Promise<any>,
+                setTx: (tx?: ClientSession) => void,
+            ) => {
+                return connection.transaction((session) => {
+                    setTx(session);
+                    return fn();
+                }, options);
+            },
+            getFallbackInstance: () => null,
+        };
+    }
+}