JavaScript implementation of MongoDB query language
Latest commit a1d7de6 Sep 9, 2018

README.md

mingo

JavaScript implementation of MongoDB query language

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Install

$ npm install mingo

Features

For documentation on using query operators see mongodb

Documentation

Usage

On the server side

// Use as es6 module
import mingo from 'mingo'

// or vanilla nodeJS
var mingo = require('mingo')

For the browser

// minified UMD module
<script type="text/javascript" src="./dist/mingo.min.js"></script>

// or gzipped UMD module
<script type="text/javascript" src="./dist/mingo.min.js.gz"></script>

Tiny configuration if needed

// setup the key field for your collection
mingo.setup({
    key: '_id' // default
});

Using query object to test objects

// create a query with criteria
// find all grades for homework with score >= 50
let query = new mingo.Query({
    type: "homework",
    score: { $gte: 50 }
});

// test if an object matches query
query.test(someObject)

Searching and Filtering

// input is either an Array or any iterable source (i.e Object{next:Function}) including ES6 generators.

// filter collection with find()
let cursor = query.find(collection)

// shorthand with query criteria
cursor = mingo.find(collection, criteria)

// sort, skip and limit by chaining
cursor.sort({student_id: 1, score: -1})
    .skip(100)
    .limit(100)

// count matches. exhausts cursor
cursor.count()

// classic cursor iterator (old school)
while (cursor.hasNext()) {
    console.log(cursor.next())
}

// ES6 iterators (new cool)
for (let value of cursor) {
  console.log(value)
}

// all() to retrieve matched objects. exhausts cursor
cursor.all()

Aggregation Pipeline

let agg = new mingo.Aggregator([
    {'$match': { "type": "homework"}},
    {'$group':{'_id':'$student_id', 'score':{$min:'$score'}}},
    {'$sort':{'_id': 1, 'score': 1}}
])

// return an iterator for streaming results
let stream = agg.stream(collection)

// return all results. same as `stream.all()`
let result = agg.run(collection)

Integration with custom collection

// using Backbone.Collection as an example (any user-defined object will do)
let Grades = Backbone.Collection.extend(mingo.CollectionMixin)

// `collection` is an array of objects
let grades = new Grades(collection)

// find students with grades less than 50 in homework or quiz
// sort by score ascending and type descending
cursor = grades.query({
  $or: [{type: "quiz", score: {$lt: 50}}, {type: "homework", score: {$lt: 50}}]
}).sort({score: 1, type: -1}).limit(10)

// return grade with the lowest score
cursor.next()

The collection to mixin needs to provide a method with signature toJSON() -> Array[Object].

Why?

  • Alternative to writing lots of custom code for transforming collection of objects
  • Quick validation of MongoDB queries without the need for a database
  • MongoDB query language is among the best in the market and is well documented

Contributing

  • Submit pull requests to the development branch
  • Squash changes into one commit
  • Run make to ensure build and tests pass

License

MIT