forked from zhurui/management
90 lines
1.7 KiB
Markdown
90 lines
1.7 KiB
Markdown
# unique-stream
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node.js through stream that emits a unique stream of objects based on criteria
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[](http://travis-ci.org/eugeneware/unique-stream)
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## Installation
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Install via npm:
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```
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$ npm install unique-stream
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```
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## Examples
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### Dedupe a ReadStream based on JSON.stringify:
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``` js
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var unique = require('unique-stream')
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, Stream = require('stream');
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// return a stream of 3 identical objects
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function makeStreamOfObjects() {
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var s = new Stream;
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s.readable = true;
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var count = 3;
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for (var i = 0; i < 3; i++) {
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setImmediate(function () {
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s.emit('data', { name: 'Bob', number: 123 });
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--count && end();
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});
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}
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function end() {
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s.emit('end');
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}
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return s;
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}
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// Will only print out one object as the rest are dupes. (Uses JSON.stringify)
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makeStreamOfObjects()
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.pipe(unique())
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.on('data', console.log);
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```
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### Dedupe a ReadStream based on an object property:
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``` js
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// Use name as the key field to dedupe on. Will only print one object
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makeStreamOfObjects()
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.pipe(unique('name'))
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.on('data', console.log);
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```
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### Dedupe a ReadStream based on a custom function:
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``` js
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// Use a custom function to dedupe on. Use the 'number' field. Will only print one object.
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makeStreamOfObjects()
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.pipe(function (data) {
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return data.number;
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})
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.on('data', console.log);
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```
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## Dedupe multiple streams
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The reason I wrote this was to dedupe multiple object streams:
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``` js
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var aggregator = unique();
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// Stream 1
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makeStreamOfObjects()
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.pipe(aggregator);
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// Stream 2
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makeStreamOfObjects()
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.pipe(aggregator);
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// Stream 3
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makeStreamOfObjects()
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.pipe(aggregator);
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aggregator.on('data', console.log);
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```
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