# geyser-mongo

> Publish and subscribe to streams of data over MongoDB

Latest version **1.0.0-beta.1** (published 2017-08-24) · MIT license · 0 weekly downloads

## Install

```sh
npm install geyser-mongo
pnpm add geyser-mongo
yarn add geyser-mongo
bun add geyser-mongo
```

## Health

**Score 25/100 (F)** — status: abandoned.

Positive: has types; no vulnerabilities; high quality score.

Warnings: low downloads; no esm support.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 1.0.0-beta.1 |
| Published | 2017-08-24 |
| First published | 2017-08-24 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | bundled |
| Module format | CommonJS |
| Node | >=4.5 |
| Dependencies | 3 |
| Known vulnerabilities | 0 (+1 in 1 direct dependencies) |
| Install scripts | no |
| GitHub stars | 1 |
| Author | Jason Dreyzehner |
| Maintainers | jasondreyzehner |
| Keywords | mongo, pubsub, rxjs |

## Links

- npm: https://www.npmjs.com/package/geyser-mongo
- Repository: https://github.com/bitjson/geyser
- Homepage: https://github.com/bitjson/geyser#readme
- Issues: https://github.com/bitjson/geyser/issues
- npm.io page: https://npm.io/package/geyser-mongo

## Dependencies (3)

- [rxjs](https://npm.io/package/rxjs.md) ^5.4.3
- [tslib](https://npm.io/package/tslib.md) ^1.6.0
- [mongodb](https://npm.io/package/mongodb.md) ^2.2.31

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## Recent versions

- 1.0.0-beta.1 (latest) — 2017-08-24

## README

[![Build Status](https://travis-ci.org/bitjson/geyser.svg?branch=master)](https://travis-ci.org/bitjson/geyser)
[![Codecov](https://img.shields.io/codecov/c/github/bitjson/geyser.svg)](https://codecov.io/gh/bitjson/geyser)
[![NPM version](https://img.shields.io/npm/v/geyser-mongo.svg)](https://www.npmjs.com/package/geyser-mongo)
[![Standard Version](https://img.shields.io/badge/release-standard%20version-brightgreen.svg)](https://github.com/conventional-changelog/standard-version)
[![dependencies Status](https://david-dm.org/bitjson/geyser/status.svg)](https://david-dm.org/bitjson/geyser)
[![devDependencies Status](https://david-dm.org/bitjson/geyser/dev-status.svg)](https://david-dm.org/bitjson/geyser?type=dev)

# Geyser

Publish and subscribe to streams of data over MongoDB.

## Example

In the source Node.js process, create a MongoObserver which writes to a `ticks` collection in MongoDB. Then subscribe it to a data source (in this example, an interval).

```js
import { Observable } from 'rxjs';
import { MongoObserver } from 'geyser-mongo';

const ticks = MongoObserver.create({
  db: 'mongodb://localhost/my-db',
  collection: 'ticks'
});

Observable.interval(1000).take(5).subscribe(ticks);
```

In the listening Node.js process, create a MongoObservable which emits messages written to the "ticks" collection.

```js
import { MongoObservable } from 'geyser-mongo';

const ticks = MongoObservable.create({
  db: 'mongodb://localhost/my-db',
  collection: 'ticks'
}).subscribe({
  next: console.log,
  complete: () => console.log('Complete.'),
  error: console.error
});

// 0
// 1
// 2
// 3
// 4
// Complete.
```

Each time a value is delivered to the MongoObserver, the MongoSubscriber will emit. The observable will also emit `error` and `complete` signals.

### Using an Existing MongoDB Connection

`MongoObservable` and `MongoObserver` can also be created from an existing MongoDB connection. The following example is a simple latency test.

```js
import { MongoClient } from "mongodb";
import { Observable } from 'rxjs';
import { MongoObservable, MongoObserver } from 'geyser-mongo';

MongoClient.connect(url).then(db => {
  const ticksIn = MongoObserver.create({
    collection: "ticks",
    db
  });

  const ticksOut = MongoObservable.create({
    collection: "ticks",
    db
  });

  Observable.interval(1000)
    .take(60)
    .map(i => i.toString())
    .startWith("connect")
    .do(i => console.time(i))
    .subscribe(ticksIn);

  ticksOut.subscribe({
    complete: () => db.close(),
    next: (i: string) => console.timeEnd(i)
  });
}
```

This example also demonstrates MongoObserver's internal buffering before it's connected to the database.

### Connecting the MongoObserver Early

Internally, MongoObserver calls it's `connect` method when it receives it's first event. It's possible to `connect` the MongoObserver early to reduce internal buffering.

```js
import { Observable } from 'rxjs';
import { MongoObserver } from 'geyser-mongo';

const ticks = MongoObserver.create({
  db: 'mongodb://localhost/my-db',
  collection: 'ticks'
}).connect(console.error, () => console.log("MongoObserver connected."));

Observable.interval(1000).take(5).subscribe(ticks);
```

### MongoObserver Internal Buffer

The `MongoObserver.connect` method prepares the capped collection used by Geyser to pass events from one process to the other. Any events passed to the MongoObserver before the database connection is ready will be saved to the observer's internal buffer and replayed once ready.

For finer-grained control (or to avoid this internal buffer), the pre-connected MongoObserver can also be obtained via subscription.

```js
import { Observable } from 'rxjs';
import { MongoObserver } from 'geyser-mongo';

MongoObserver.create({
  db: 'mongodb://localhost/my-db',
  collection: 'ticks'
}).subscribe(ticks => {
  Observable.interval(1000).take(5).subscribe(ticks);
});
```

---
_Source: https://npm.io/package/geyser-mongo · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._