@e2fyi/streams
Version:
Nodejs stream library for various use cases: e.g. Auto-tagging object streams, streaming to mongoDb via mongoose models, etc.
117 lines (95 loc) • 3.48 kB
HTML
<html lang="en">
<head>
<meta charset="utf-8">
<title>JSDoc: Source: src/mongoose_stream.js</title>
<script src="scripts/prettify/prettify.js"> </script>
<script src="scripts/prettify/lang-css.js"> </script>
<!--[if lt IE 9]>
<script src="//html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
<link type="text/css" rel="stylesheet" href="styles/prettify-tomorrow.css">
<link type="text/css" rel="stylesheet" href="styles/jsdoc-default.css">
</head>
<body>
<div id="main">
<h1 class="page-title">Source: src/mongoose_stream.js</h1>
<section>
<article>
<pre class="prettyprint source linenums"><code>`use strict`;
const {Transform} = require('stream');
const defaultOpts = {objectMode: true, itemWaterMark: 50};
/**
* Settings for MongooseStream.
* @memberof module:@e2fyi/streams
* @alias MongooseStreamSettings
* @typedef {Object} MongooseStreamSettings
* @property {Number} [itemWaterMark=50] - The number of item collected before writing to mongodb.
* @property {mongoose.Model} model - [mongoose Model]{@link http://mongoosejs.com/docs/models.html}.
*/
/**
* A custom NodeJS Transform stream to mongo via mongoose.
* @memberof module:@e2fyi/streams
* @extends stream.Transform
* @example
* var stream2mongo = new MongooseStream({mode: SomeMongooseModel});
* someReadableStreamFromArray([{text: 'abc'}, {text: 'efg'}])
* .pipe(stream2mongo) // writes to mongo (while stream are also passthrough)
* .pipe(response); // stream same results back to some request
*/
class MongooseStream extends Transform {
/**
* Create a Transform stream which bulkWrite to mongo based on the itemWaterMark.
* model (mongoose Model) is a required field.
* @param {MongooseStreamSettings} opts Configuration for MongoStream. Default value for `itemWaterMark` is 50.
*/
constructor(opts = defaultOpts) {
opts = Object.assign(opts, defaultOpts);
super(opts);
this.itemWaterMark = opts.itemWaterMark;
this.model = opts.model;
this._stack_ = [];
if (!opts.model) {
throw new Error('Mongoose Model must be defined!');
}
}
_transform(chunk, encoding, callback) {
if (chunk) {
this._stack_.push({insertOne: {document: chunk}});
if (this._stack_.length >= this.itemWaterMark) {
let job = this._stack_;
this._stack_ = [];
return this.model.bulkWrite(job, err => {
callback(err, chunk);
});
}
}
callback(null, chunk);
}
_flush(callback) {
if (this._stack_.length > 0) {
let job = this._stack_;
this._stack_ = [];
return this.model.bulkWrite(job, err => {
callback(err, '\0');
});
}
callback(null, '\0');
}
}
module.exports = MongooseStream;
</code></pre>
</article>
</section>
</div>
<nav>
<h2><a href="index.html">Home</a></h2><h3>Modules</h3><ul><li><a href="module-@e2fyi_streams.html">@e2fyi/streams</a></li></ul><h3>Classes</h3><ul><li><a href="module-@e2fyi_streams.DocumentTagger.html">DocumentTagger</a></li><li><a href="module-@e2fyi_streams.MongooseStream.html">MongooseStream</a></li></ul>
</nav>
<br class="clear">
<footer>
Documentation generated by <a href="https://github.com/jsdoc3/jsdoc">JSDoc 3.6.0</a> on Wed Dec 13 2017 18:11:13 GMT+0800 (+08)
</footer>
<script> prettyPrint(); </script>
<script src="scripts/linenumber.js"> </script>
</body>
</html>