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    unique-streampublic

    unique-stream

    node.js through stream that emits a unique stream of objects based on criteria

    Build Status Coverage Status

    Installation

    Install via npm:

    $ npm install unique-stream
    

    Examples

    Dedupe a ReadStream based on JSON.stringify:

    var unique = require('unique-stream')
      , Stream = require('stream');
     
    // return a stream of 3 identical objects
    function makeStreamOfObjects() {
      var s = new Stream;
      s.readable = true;
      var count = 3;
      for (var i = 0; i < 3; i++) {
        setImmediate(function () {
          s.emit('data', { name: 'Bob', number: 123 });
          --count || end();
        });
      }
     
      function end() {
        s.emit('end');
      }
     
      return s;
    }
     
    // Will only print out one object as the rest are dupes. (Uses JSON.stringify)
    makeStreamOfObjects()
      .pipe(unique())
      .on('data', console.log);
     

    Dedupe a ReadStream based on an object property:

    // Use name as the key field to dedupe on. Will only print one object
    makeStreamOfObjects()
      .pipe(unique('name'))
      .on('data', console.log);

    Dedupe a ReadStream based on a custom function:

    // Use a custom function to dedupe on. Use the 'number' field. Will only print one object.
    makeStreamOfObjects()
      .pipe(function (data) {
        return data.number;
      })
      .on('data', console.log);

    Dedupe multiple streams

    The reason I wrote this was to dedupe multiple object streams:

    var aggregator = unique();
     
    // Stream 1
    makeStreamOfObjects()
      .pipe(aggregator);
     
    // Stream 2
    makeStreamOfObjects()
      .pipe(aggregator);
     
    // Stream 3
    makeStreamOfObjects()
      .pipe(aggregator);
     
    aggregator.on('data', console.log);

    Use a custom store to record keys that have been encountered

    By default a set is used to store keys encountered so far, in order to check new ones for uniqueness. You can supply your own store instead, providing it supports the add(key) and has(key) methods. This could allow you to use a persistant store so that already encountered objects are not re-streamed when node is reloaded.

    var keyStore = {
      store: {},
     
      add: function(key) {
        this.store[key] = true;
      },
     
      has: function(key) {
        return this.store[key] !== undefined;
      }
    };
        
    makeStreamOfObjects()
      .pipe(unique('name', keyStore))
      .on('data', console.log);

    Contributing

    unique-stream is an OPEN Open Source Project. This means that:

    Individuals making significant and valuable contributions are given commit-access to the project to contribute as they see fit. This project is more like an open wiki than a standard guarded open source project.

    See the CONTRIBUTING.md file for more details.

    Contributors

    unique-stream is only possible due to the excellent work of the following contributors:

    Eugene WareGitHub/eugeneware
    Craig AmbroseGitHub/craigambrose
    Shinnosuke WatanabeGitHub/shinnn

    install

    npm i unique-stream

    Downloadsweekly downloads

    1,619,296

    version

    2.2.1

    license

    MIT

    repository

    githubgithub

    last publish

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