flatley

Take a nested Javascript object and flatten it, or unflatten an object with delimited keys.

Credits

Based on 'flat' by Hugh Kennedy (http://hughskennedy.com)

Installation

$ npm install flatley

Methods

flatten(original, options)

Flattens the object - it'll return an object one level deep, regardless of how nested the original object was:

var flatten = require('flatley')

flatten({
    key1: {
        keyA: 'valueI'
    },
    key2: {
        keyB: 'valueII'
    },
    key3: { a: { b: { c: 2 } } }
})

// {
//   'key1.keyA': 'valueI',
//   'key2.keyB': 'valueII',
//   'key3.a.b.c': 2
// }

unflatten(original, options)

Flattening is reversible too, you can call flatten.unflatten() on an object:

var unflatten = require('flatley').unflatten

unflatten({
    'three.levels.deep': 42,
    'three.levels': {
        nested: true
    }
})

// {
//     three: {
//         levels: {
//             deep: 42,
//             nested: true
//         }
//     }
// }

Options

delimiter

Use a custom delimiter for (un)flattening your objects, instead of ..

safe

When enabled, both flat and unflatten will preserve arrays and their contents. This is disabled by default.

var flatten = require('flatley')

flatten({
    this: [
        { contains: 'arrays' },
        { preserving: {
              them: 'for you'
        }}
    ]
}, {
    safe: true
})

// {
//     'this': [
//         { contains: 'arrays' },
//         { preserving: {
//             them: 'for you'
//         }}
//     ]
// }

object

When enabled, arrays will not be created automatically when calling unflatten, like so:

unflatten({
    'hello.you.0': 'ipsum',
    'hello.you.1': 'lorem',
    'hello.other.world': 'foo'
}, { object: true })

// hello: {
//     you: {
//         0: 'ipsum',
//         1: 'lorem',
//     },
//     other: { world: 'foo' }
// }

overwrite

When enabled, existing keys in the unflattened object may be overwritten if they cannot hold a newly encountered nested value:

unflatten({
    'TRAVIS': 'true',
    'TRAVIS_DIR': '/home/travis/build/kvz/environmental'
}, { overwrite: true })

// TRAVIS: {
//     DIR: '/home/travis/build/kvz/environmental'
// }

Without overwrite set to true, the TRAVIS key would already have been set to a string, thus could not accept the nested DIR element.

This only makes sense on ordered arrays, and since we're overwriting data, should be used with care.

maxDepth

Maximum number of nested objects to flatten.

var flatten = require('flatley')

flatten({
    key1: {
        keyA: 'valueI'
    },
    key2: {
        keyB: 'valueII'
    },
    key3: { a: { b: { c: 2 } } }
}, { maxDepth: 2 })

// {
//   'key1.keyA': 'valueI',
//   'key2.keyB': 'valueII',
//   'key3.a': { b: { c: 2 } }
// }

coercion

Optionally run a test/set of tests on your incoming key/value(s) and transform the resulting value if it matches.

This is particularly useful in the case of transforming https://www.npmjs.com/package/mongoose ObjectIds

var ObjectId = mongoose.Types.ObjectId

var coercion = [{
    test: function (key, value) { return key === '_id' && ObjectId.isValid(value) }
    transform: function (value) { return value.valueOf() }
}]
var options = { coercion: coercion }

flatten({
    group1: {
        prop1: ObjectId('aaabbbcccdddeee')
    }
}, options)

// {
//    'group1.prop1': 'aaabbbcccdddeee'
// }

filtering

Optionally run a test/set of tests on your incoming key/value(s) and don't transform this key's children if it matches.

const someObject = {
    prop1: 'abc',
    prop2: 'def'
}

var filters = [{
    test: function (key, value) { return value.prop1 === 'abc' }
}]
var options = { filters: filters }

flatten({
    group1: {
        someObject: someObject
    }
}, options)

// {
//    'group1.someObject': {
//      'prop1': 'abc',
//      'prop2': 'def'
//    }
// }

## Command Line Usage

`flat` is also available as a command line tool. You can run it with 
[`npx`](https://ghub.io/npx):

```sh
npx flatley foo.json

Or install the flatley command globally:

npm i -g flatley && flatley foo.json

Accepts a filename as an argument:

flatley foo.json

Also accepts JSON on stdin:

cat foo.json | flatley