At a Glance

DeepQuery.js solves the problem of null element inside of long object chain.

How to Get Started

Type in Terminal:

npm install --save @imatyushkin/deep-query

or, if you prefer yarn over npm, type:

yarn add @imatyushkin/deep-query

Usage

Simple Query

Let's assume we have some JavaScript object with complicated structure of nested objects:

var obj = {
    a: {
        b: [
            { val: [1,2,3] },
            { val: [4,5,6] },
            { val: null },
        ]
    }
};

Now, we want to obtain a value located very deep in the tree:

var regularQuery = obj.a.b[2].val[0] // CRASH 😡

We'll get crash because the val is null, which might be an unexpected case. To avoid this, we could implement a more complicated logic based on data structure:

var safeQuery = (() => {
    var intermediateResult = obj.a.b[2];
    return intermediateResult.val ? intermediateResult.val[0] : null;
})();

With DeepQuery.js it works significantly easier:

import "@imatyushkin/deep-query"

var query = obj.__("a.b.2.val.0") // No crash, just null will be returned 🙂
var anotherQuery = obj.__("a.b.1.val.0") // 4

Filter

Here's example of query with data filter:

var data = {
    users: [
        {
            name: "John",
            points: [10,9,5]
        },
        {
            name: "Donald",
            points: [8, 4, 2]
        }
    ]
}

var pointsOfJohn = data.__("users.name:John.0.points") // [10, 9, 5]

Multiline Query

For convenience, you may use a multiline expression:

// Instead of
var pointsOfJohn = data.__("users.name:John.0.points")

// use
var pointsOfJohn = data.__(`
    users
    .name:John.0
    .points
`)

License

DeepQuery.js is available under the Apache 2.0 license. See the LICENSE file for more info.