Mingo

JavaScript implementation of MongoDB query language

Dependencies

underscore

Installing

$ npm install mingo

In browser

<script type="text/javascript" src="./mingo-min.js"></script>

Features

• Comparisons Operators ($gt, $gte, $lt, $lte, $ne, $nin, $in)
• Logical Operators ($and, $or, $nor, $not)
• Evaluation Operators ($regex, $mod, $where)
• Array Operators ($all, $elemMatch, $size)
• Element Operators ($exists, $type)
• Aggregation Pipeline Operators ($group, $match, $project, $sort, $limit, $unwind, $skip)
• Conditional Operators ($cond, $ifNull)
• Group Operators ($addToSet, $sum, $max, $min, $avg, $push, $first, $last)
• Arithmetic Operators ($add, $divide, $mod, $multiply, $subtract)
• String Operators ($cmp, $strcasecmp, $concat, $substr, $toLower, $toUpper)
• Set Operators ($setEquals, $setIntersection, $setDifference, $setUnion, $setIsSubset, $anyElementTrue, $allElementsTrue)
• Projection Operators ($elemMatch, $slice)
• JSON stream filtering and projection. NodeJS only

Usage

var Mingo = require('mingo');
// or just access *Mingo* global in browser

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

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

Searching and Filtering

// filter collection with find()
var 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
cursor.count();

// iterate cursor
// iteration is forward only
while (cursor.hasNext()) {
    console.log(cursor.next());
}

// use first(), last() and all() to retrieve matched objects
cursor.first();
cursor.last();
cursor.all();

// Filter non-matched objects
var result = query.remove(collection);

a.pipe(query).pipe(process.stdout);

Aggregation Pipeline

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

var result = agg.run(collection);

// shorthand
result = Mingo.aggregate(
    collection,
    [
        {'$match': { "type": "homework"}},
        {'$group':{'_id':'$student_id', 'score':{$min:'$score'}}},
        {'$sort':{'_id': 1, 'score': 1}}
    ]
);

Stream Filtering

var JSONStream = require('JSONStream'),
    fs = require('fs'),
    Mingo = require('mingo');

var query = new Mingo.Query({
  scores: { $elemMatch: {type: "exam", score: {$gt: 90}} }
}, {name: 1});

// ex. [
//      { "_id" : 11, "name" : "Marcus Blohm", "scores" : [
//          { "type" : "exam", "score" : 78.42617835651868 },
//          { "type" : "quiz", "score" : 82.58372817930675 },
//          { "type" : "homework", "score" : 87.49924733328717 },
//          { "type" : "homework", "score" : 15.81264595052612 } ]
//      },
//      ...
//     ]
file = fs.createReadStream('./students.json');

var qs = query.stream();
qs.on('data', function (data) {
    console.log(data); // log filtered outputs
    // ex. { name: 'Dinah Sauve', _id: 49 }
});

file.pipe(JSONStream.parse("*")).pipe(qs);

Backbone Integration

// using with Backbone
var Grades = Backbone.Collection.extend(Mingo.CollectionMixin);

var 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);

// print grade with the lowest score
cursor.first();

For documentation on using query operators see mongodb

API

Mingo.Query(criteria, [projection])

Creates a Mingo.Query object with the given query criteria

• test(obj) Returns true if the object passes the query criteria, otherwise false.
• find(collection, [projection]) Performs a query on a collection and returns a Mingo.Cursor object.
• remove(collection) Remove matching documents from the collection and return the remainder
• stream() Return a Mingo.Stream to filter and transform JSON objects from a readable stream. NodeJS only

Mingo.Aggregator(expressions)

Creates a Mingo.Aggregator object with a collection of aggregation pipeline expressions

• run() Apply the pipeline operations over the collection by order of the sequence added

Mingo.Cursor(collection, query, [projection])

Creates a Mingo.Cursor object which holds the result of applying the query over the collection

• all() Returns all the matched documents in a cursor as a collection.
• first() Returns the first documents in a cursor.
• last() Returns the last document in a cursor
• count() Returns a count of the documents in a cursor.
• limit(n) Constrains the size of a cursor's result set.
• skip(n) Returns a cursor that begins returning results only after passing or skipping a number of documents.
• sort(modifier) Returns results ordered according to a sort specification.
• next() Returns the next document in a cursor.
• hasNext() Returns true if the cursor has documents and can be iterated.
• max(expression) Specifies an exclusive upper index bound for a cursor
• min(expression) Specifies an inclusive lower index bound for a cursor.
• map(callback) Applies a function to each document in a cursor and collects the return values in an array.
• forEach(callback) Applies a JavaScript function for every document in a cursor.

Mingo.Stream(query, [options]) - NodeJS only

A Transform stream that can be piped from/to any readable/writable JSON stream.

Mingo.CollectionMixin

A mixin object for Backbone.Collection which adds query() and aggregate() methods

• query(criteria) Performs a query on the collection and returns a Mingo.Cursor object.
• aggregate(expressions) Performs aggregation operation using the aggregation pipeline.

Mingo.find(collection, criteria, [projection])

Performs a query on a collection and returns a Mingo.Cursor object.

Mingo.remove(collection, criteria)

Returns the non-matched objects as a collection from executing a Mingo.Query with the given criteria

Mingo.aggregate(collection, expressions)

Performs aggregation operation using the aggregation pipeline.

TODO

• Geospatial Query Operators ($geoWithin, $geoIntersects, $near, $nearSphere)
• Geometry Specifiers ($geometry, $maxDistance, $center, $centerSphere, $box, $polygon)

License

MIT