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jsonstream

rawStream.pipe(JSONStream.parse()).pipe(streamOfObjects)

    1.0.3latest
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    npm

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JSONStream

streaming JSON.parse and stringify

example


var request = require('request')
  , JSONStream = require('JSONStream')
  , es = require('event-stream')

request({url: 'http://isaacs.couchone.com/registry/_all_docs'})
  .pipe(JSONStream.parse('rows.*'))
  .pipe(es.mapSync(function (data) {
    console.error(data)
    return data
  }))

JSONStream.parse(path)

parse stream of values that match a path

  JSONStream.parse('rows.*.doc')

The .. operator is the recursive descent operator from JSONPath, which will match a child at any depth (see examples below).

If your keys have keys that include . or * etc, use an array instead. ['row', true, /^doc/].

If you use an array, RegExps, booleans, and/or functions. The .. operator is also available in array representation, using {recurse: true}. any object that matches the path will be emitted as 'data' (and piped down stream)

If path is empty or null, no 'data' events are emitted.

Examples

query a couchdb view:

curl -sS localhost:5984/tests/_all_docs&include_docs=true

you will get something like this:

{"total_rows":129,"offset":0,"rows":[
  { "id":"change1_0.6995461115147918"
  , "key":"change1_0.6995461115147918"
  , "value":{"rev":"1-e240bae28c7bb3667f02760f6398d508"}
  , "doc":{
      "_id":  "change1_0.6995461115147918"
    , "_rev": "1-e240bae28c7bb3667f02760f6398d508","hello":1}
  },
  { "id":"change2_0.6995461115147918"
  , "key":"change2_0.6995461115147918"
  , "value":{"rev":"1-13677d36b98c0c075145bb8975105153"}
  , "doc":{
      "_id":"change2_0.6995461115147918"
    , "_rev":"1-13677d36b98c0c075145bb8975105153"
    , "hello":2
    }
  },
]}

we are probably most interested in the rows.*.doc

create a Stream that parses the documents from the feed like this:

var stream = JSONStream.parse(['rows', true, 'doc']) //rows, ANYTHING, doc

stream.on('data', function(data) {
  console.log('received:', data);
});

awesome!

recursive patterns (..)

JSONStream.parse('docs..value') (or JSONStream.parse(['docs', {recurse: true}, 'value']) using an array) will emit every value object that is a child, grand-child, etc. of the docs object. In this example, it will match exactly 5 times at various depth levels, emitting 0, 1, 2, 3 and 4 as results.

{
  "total": 5,
  "docs": [
    {
      "key": {
        "value": 0,
        "some": "property"
      }
    },
    {"value": 1},
    {"value": 2},
    {"blbl": [{}, {"a":0, "b":1, "value":3}, 10]},
    {"value": 4}
  ]
}

JSONStream.parse(pattern, map)

provide a function that can be used to map or filter the json output. map is passed the value at that node of the pattern, if map return non-nullish (anything but null or undefined) that value will be emitted in the stream. If it returns a nullish value, nothing will be emitted.

JSONStream.stringify(open, sep, close)

Create a writable stream.

you may pass in custom open, close, and seperator strings. But, by default, JSONStream.stringify() will create an array, (with default options open='[\n', sep='\n,\n', close='\n]\n')

If you call JSONStream.stringify(false) the elements will only be seperated by a newline.

If you only write one item this will be valid JSON.

If you write many items, you can use a RegExp to split it into valid chunks.

JSONStream.stringifyObject(open, sep, close)

Very much like JSONStream.stringify, but creates a writable stream for objects instead of arrays.

Accordingly, open='{\n', sep='\n,\n', close='\n}\n'.

When you .write() to the stream you must supply an array with [ key, data ] as the first argument.

unix tool

query npm to see all the modules that browserify has ever depended on.

curl https://registry.npmjs.org/browserify | JSONStream 'versions.*.dependencies'

numbers

There are occasional problems parsing and unparsing very precise numbers.

I have opened an issue here:

https://github.com/creationix/jsonparse/issues/2

+1

Acknowlegements

this module depends on https://github.com/creationix/jsonparse by Tim Caswell and also thanks to Florent Jaby for teaching me about parsing with: https://github.com/Floby/node-json-streams

license

MIT / APACHE2

Keywords

FAQs

Last updated on 30 Apr 2015

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Socket installs a GitHub app to automatically flag issues on every pull request and report the health of your dependencies. Find out what is inside your node modules and prevent malicious activity before you update the dependencies.

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