# moleculer-context-db

A database integrator for injecting a transaction safe database session into the
context of the action. Currently, this only has built in support for [Mikro-ORM](https://mikro-orm.io/), and in that only SQL databases have been tested. Mongo support is experimental.

## Setup

### Installation

To install with npm

```shell script
npm install moleculer-context-db
```

`moleculer` and `@mikro-orm/core` are peer dependecies and need to be installed separately.

### Importing

ES6 style

```js
import { MikroConnector, DatabaseContextManager } from 'moleculer-context-db';
```

CommonJS

```js
const {
  MikroConnector,
  DatabaseContextManager
} = require('moleculer-context-db');
```

### Configuration

You can create a new MikroConnector as such

```js
const connector = new MikroConnector();
```

You will also need to install the appropriate database driver, e.g.:

```js
import {MongoDriver} from '@mikro-orm/mongodb';

const connector = new MikroConnector<MongoDriver>();
```

or

```js
npm i @mikro-orm/sqlite;

const connector = new MikroConnector();
```

You will then need to initialize the connector

```js
await connector.init({
  type: 'sqlite', // or use 'mongo' for mongodb
  dbName: ':memory',
  entities: [YourEntity1, YourEntity2],
  cache: {
    enabled: false
  }
});
```

For mongo support, you will need to do:

```js
await connector.init({
  type: 'mongo', // or use 'mongo' for mongodb
  dbName: <name_of_db>,
  clientUrl: <mongo_url>
  entities: [YourEntity1, YourEntity2],
  cache: {
    enabled: false
  },
  implicitTransactions: <true/false> // needs to be true if you are running a replica set needing transaction support
});
```

You can use all available options for MikroORM.init()

## Usage

To use, simply instantiate a DatabaseContextManager with the connector and then add
the result of the middleware method to your broker's middleware

```javascript
const dbContextManager: DatabaseContextManager = new DatabaseContextManager(
  connector
);

yourMoleculerBroker.middlewares.add(DatabaseContextManager.middleware());
```

The above statement will wrap all local actions with a Mikro-ORM transaction.