README.md

@barreljs/json-filter

A simple library to parse out specific elements of a larger JSON object or JSON array based on a provided JSON filter. This makes it easier to filter out key-value pairs on any given JSON object, even more complex filter object are supported if you feel like that (feel free to check out the tests on examples).

• Installation
• Getting started
• Filter
• Result
• License

Installation

Install via npm

npm install @barreljs/json-filter

or yarn

yarn add @barreljs/json-filter

Getting started

Let's take a very simple JSON object as example ...

const json = {
    actions: [
        {
            type: 'visit',
            property: 'website'
        },
        {
            type: 'click',
            property: 'site_signup'
        },
        {
            type: 'click',
            property: 'site_pricing'
        }
    ],
    property: 'other'
}

... and define a simple filter to get all actions that are of {type: 'click'}

const filter = {
    type: 'click'
}

You can now easily filter the original JSON object with the given filter ✨

const JsonFilter = require('@barreljs/json-filter')

const result = JsonFilter(json, filter)
const elements = result.all()

This will match all elements from the JSON object that have a property type with a value of 'click'. As a result elements will look like this

[
    {
        type: 'click',
        property: 'site_signup'
    },
    {
        type: 'click',
        property: 'site_pricing'
    }
]

Filter

The filter can be any valid JSON object (arrays are not support at this point). An empty JSON filter ({}) would match all elements. I don't know why you would do that, but you can ¯\_(ツ)_/¯

RegEx

json-filter supports RegEx for filter properties

{
    property: /^site_\w*$/
}

$any

You can use the keyword $any on any filter property to match all possible values, like strings, numbers, boolean, objects, and arrays. This might not be useful in the example shown above, but can be helpful if your JSON object gets more complex.

{
    property: '$any'
}

Usage

JsonFilter(json, filter, trim)

Arguments

Argument	Required	Type	Description
json	yes	JSON	Any valid JSON object or array
filter	yes	Object	Any valid JSON object
trim	no	bool	A flag to indicate if your results should be trimmed to properties of your filter. If false the result will keep the structure of the original JSON, if true only properties defined in the filter will be returned. Default to false.

Example

const result = JsonFilter(json, filter, trim)

with trim set to false the above example will match the structure of the original JSON

[
    {
        type: 'click',
        property: 'site_signup'
    },
    {
        type: 'click',
        property: 'site_pricing'
    }
]

with trim set to true, the result will be trimmed to the structure of the filter

[
    {
        type: 'click'
    },
    {
        type: 'click'
    }
]

Result

The result is an object with following properties:

Property	Return Type	Description
length	Number	Number of matching elements
all()	Array	Returns all matching elements as a JSON array.
first()	Object	Returns the first matching element
last()	Object	Returns the last matching element
get(i)	Object	Returns the matching element on given index i

Methods

.all()

Returns all matching elements as a JSON array.

const result = JsonFilter(json, filter)
const all = result.all() // returns element array

.first()

Returns the first matching element. If no elements match, returns undefined.

const result = JsonFilter(json, filter)
const first = result.first() // returns first element

.last()

Returns the last matching element. If no elements match, returns undefined. If only one element exists, it returns the same element as .first().

const result = JsonFilter(json, filter)
const last = result.last() // returns last element

.get(index)

Returns the matching element on given index or undefined if no element on that index exists. Index starts at 0.

const result = JsonFilter(json, filter)
const element = result.get(3) // returns 4th element

License

This project is licensed under the MIT license, Copyright (c) 2020 David Pichsenmeister | pichsenmeister.com. For more information see LICENSE.