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Querying a MongoDB collection using DevExtreme data store load parameters

The JavaScript library DevExtreme by DevExpress includes a highly advanced data layer. Many of the complex data-bound UI widgets in the library utilize the data layer infrastructure to load server-provided data efficiently.

When data is loaded by a data source attached to a UI widget (or by code interaction with the data source), the underlying data store receives a call to its load function, and a parameter object is passed that I will refer to as loadOptions. If you implement a custom store to load data from your own server through a service interface, the server will (or should!) receive the loadOptions and query data accordingly.

The library devextreme-query-mongodb implements the required logic to query data from a MongoDB collection, parametrized by a DevExtreme loadOptions object.

Requirements

devextreme-query-mongodb requires at least version 7.3 of Node.js, and you need to pass the --harmony flag when running node (unless you're using the latest 8.x nightly builds, where --harmony is not required anymore). The reason for this requirement is that devextreme-query-mongodb uses async and await.

Installing devextreme-query-mongodb

The library is available through npm:

npm install devextreme-query-mongodb

Running queries

The Query API is simple, it only supplies one call. The following block of code runs a query, assuming the MongoDB connection parameters are correct for your setup, and the collection values exists with items that have a intval field:

const MongoClient = require("mongodb").MongoClient;
const query = require("devextreme-query-mongodb");

async function queryData() {
	MongoClient.connect("mongodb://localhost:27017/testdatabase", (err, db) => {
		const results = await query(db.collection("values"), {
			// This is the loadOptions object - pass in any valid parameters
			take: 10,
			filter: [ "intval", ">", 47 ],
			sort: [ { selector: "intval", desc: true }]
		});
		
		// Now "results" contains an array of ten or fewer documents from the 
		// "values" collection that have intval > 47, sorted descendingly by intval.
	});
}

Please see the Query API page for more details.