@e2fyi/streams

This NodeJS library provides custom NodeJS streams for specific use cases.

Currently, the following streams are available:

• DocumentTagger: A Transform stream to tag an auto-increment field to each object in the stream. Can also mutate the stream objects through a function or default Object.

• MongooseStream: A Transform stream which will bulk write the objects in the stream to mongodb via a mongoose model.

ChangeLog

• v1.0.0: new streams: DocumentTagger, MongooseStream.

Quick start

Using CommonJS module

// importing DocumentTagger and MongooseStream
const {DocumentTagger, MongooseStream} = require('@e2fyi/streams');

API reference

The API documentation is also available at https://e2fyi.github.io/streams.

@e2fyi/streams

• @e2fyi/streams
  • .DocumentTagger ⇐ stream.Transform
    • new DocumentTagger(opts)
  • .MongooseStream ⇐ stream.Transform
    • new MongooseStream(opts)
  • .DocumentTaggerSettings : Object
  • .MongooseStreamSettings : Object

@e2fyi/streams.DocumentTagger ⇐ stream.Transform

Transform Object stream (objectMode=true) to tag with an autoIncrement id. An object or function can be optionally provided to mutate each object in the stream.

Kind: static class of @e2fyi/streams
Extends: stream.Transform
Emits: filtered

new DocumentTagger(opts)

Create a new DocumentTagger stream.

| Param | Type | Description | | --- | --- | --- | | opts | DocumentTaggerSettings | Settings for the stream. |

Example

const docTagger = new DocumentTagger({autoIncrement: 'id', mutate: { project: 'test' }});
someReadableStreamFromArray([{text: 'abc'}, {text: 'efg'}])
  .pipe(docTagger)
  .pipe(process.stdout);
// stdout >
// {"text": "abc", "id": 0, "project": "test"}
// {"text": "efg", "id": 1, "project": "test"}

@e2fyi/streams.MongooseStream ⇐ stream.Transform

A custom NodeJS Transform stream to mongo via mongoose.

Kind: static class of @e2fyi/streams
Extends: stream.Transform
Emits: mongoose-bulk-write

new MongooseStream(opts)

Create a Transform stream which bulkWrite to mongo based on the itemWaterMark. model (mongoose Model) is a required field.

| Param | Type | Description | | --- | --- | --- | | opts | MongooseStreamSettings | Configuration for MongoStream. Default value for itemWaterMark is 50. |

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

@e2fyi/streams.DocumentTaggerSettings : Object

Settings for DocumentTagger.

Kind: static typedef of @e2fyi/streams
Properties

| Name | Type | Description | | --- | --- | --- | | autoIncrement | String | The auto-increment field to tag onto the stream object. | | ignoreNonObject | Boolean | If true, no errors will be emitted when the chunk in the stream cannot be parsed into Object. | | readableObjectMode | Boolean | If true, Object will be emitted from the stream, otherwise a String or Buffer representation or will emitted instead. | | objectMode | Boolean | If true, Object will be emitted from the stream, otherwise a String or Buffer representation or will emitted instead. Overwrites writableObjectMode. | | filter | function | Function to filter the objects in the stream. Return true to keep the object. | | mutate | function | Object | Function or Object to mutate the stream. If an Object is provided, each stream object will be mutated with the Object.assign(streamObj, mutateObj). |

@e2fyi/streams.MongooseStreamSettings : Object

Settings for MongooseStream.

Kind: static typedef of @e2fyi/streams
Properties

| Name | Type | Default | Description | | --- | --- | --- | --- | | itemWaterMark | Number | 50 | The number of item collected before writing to mongodb. | | passThrough | Boolean | | If false nothing will be emitted from the stream. | | model | mongoose.Model | | mongoose Model. |

Development

Unit testing

npm test

Build documentation

npm run build