@e2fyi/streams
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Nodejs stream library for various use cases: e.g. Auto-tagging object streams, streaming to mongoDb via mongoose models, etc.
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<h1 class="page-title">Source: src/mongoose-stream.js</h1>
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<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 {Boolean} passThrough - If `false` nothing will be emitted from the stream.
* @property {mongoose.Model} model - [mongoose Model]{@link http://mongoosejs.com/docs/models.html}.
*/
/**
* `mongoose-bulk-write` event. Emits the response from the bulkWrite via mongoose.
*
* @event MongooseStream#mongoose-bulk-write
* @type {object}
*/
/**
* A custom NodeJS Transform stream to mongo via mongoose.
* @memberof module:@e2fyi/streams
* @extends stream.Transform
* @fires MongooseStream#mongoose-bulk-write
* @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._passThrough_ = opts.passThrough;
this._stack_ = [];
if (!opts.model) {
throw new Error('Mongoose Model must be defined!');
}
}
_transform(chunk, encoding, callback) {
// termination chunk
if (!chunk) {
this.push(chunk);
} else if (this._passThrough_) {
this.push(chunk);
}
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, (error, res) => {
this.emit('mongoose-bulk-write', res);
if (error) callback(error);
else callback();
});
}
}
callback();
}
_flush(callback) {
if (this._stack_.length > 0) {
let job = this._stack_;
this._stack_ = [];
return this.model.bulkWrite(job, (error, res) => {
this.emit('mongoose-bulk-write', res);
this.push(null);
if (error) callback(error);
else callback();
});
}
this.push(null);
callback();
}
}
module.exports = MongooseStream;
</code></pre>
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<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><h3>Events</h3><ul><li><a href="DocumentTagger.html#event:filtered">filtered</a></li><li><a href="MongooseStream.html#event:mongoose-bulk-write">mongoose-bulk-write</a></li></ul>
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Documentation generated by <a href="https://github.com/jsdoc3/jsdoc">JSDoc 3.6.0</a> on Thu Dec 14 2017 18:22:08 GMT+0800 (+08)
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