npm package: @makeflow/mingo
Description: JavaScript implementation of MongoDB query language
Author: Francis Asante
Latest version: 2.3.6

# mingo
JavaScript implementation of MongoDB query language

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## Install
```$ npm install mingo```

## Features
- Supports Dot Notation for both _`<array>.<index>`_ and _`<document>.<field>`_ selectors
- Query and Projection Operators
  - [Array Operators](https://docs.mongodb.com/manual/reference/operator/query-array/)
  - [Comparisons Operators](https://docs.mongodb.com/manual/reference/operator/query-comparison/)
  - [Element Operators](https://docs.mongodb.com/manual/reference/operator/query-element/)
  - [Evaluation Operators](https://docs.mongodb.com/manual/reference/operator/query-evaluation/)
  - [Logical Operators](https://docs.mongodb.com/manual/reference/operator/query-logical/)
- Aggregation Framework Operators
  - [Pipeline Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-pipeline/)
  - [Group Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-group/)
  - [Projection Operators](https://docs.mongodb.com/manual/reference/operator/projection/)
  - [Arithmetic Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-arithmetic/)
  - [Array Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-array/)
  - [Boolean Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-boolean/)
  - [Comparisons Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-comparison/)
  - [Conditional Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-conditional/)
  - [Date Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-date/)
  - [Literal Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-literal/)
  - [Set Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-set/)
  - [String Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-string/)
  - [Variable Operators](https://docs.mongodb.com/manual/reference/operator/aggregation-projection/)
- Support for adding custom operators
- Match against user-defined types
- Support for aggregaion variables
    - [`$$ROOT`,`$$CURRENT`,`$$DESCEND`,`$$PRUNE`,`$$KEEP`,`$$REMOVE`](https://docs.mongodb.com/manual/reference/aggregation-variables/)
- ES6 module compatible
- Support integrating with custom collections via mixin
- Query filter and projection streaming.

For documentation on using query operators see [mongodb](http://docs.mongodb.org/manual/reference/operator/query/)

## Documentation
- [API](https://github.com/kofrasa/mingo/wiki/API)
- [Custom Operators](https://github.com/kofrasa/mingo/wiki/Custom-Operators)

## Usage
On the server side
```js
// Use as es6 module
import mingo from 'mingo'

// or vanilla nodeJS
var mingo = require('mingo')
```

For the browser
```html
// 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
```js
// setup the key field for your collection
mingo.setup({
    key: '_id' // default
});
```

## Using query object to test objects
```js
// 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
```js
// 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
```js
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
```js
// 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](https://github.com/kofrasa/mingo/tree/development) branch
* Squash changes into one commit
* Run `make` to ensure tests pass

## License
MIT