flat 

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

Installation

`` bash
$ npm install flat
`

Methods

$3

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

` javascript
import { flatten } from 'flat'

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

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

$3

Flattening is reversible too, you can call unflatten on an object:

` javascript
import { unflatten } from 'flat'

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

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

Options

$3

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

$3

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

` javascript
import { flatten } from 'flat'

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

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

$3

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

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

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

$3

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

`javascript
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.

$3

Maximum number of nested objects to flatten.

` javascript
import { flatten } from 'flat'

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 } }
// }
`

$3

Transform each part of a flat key before and after flattening.

`javascript
import { flatten, unflatten } from 'flat'

flatten({
key1: {
keyA: 'valueI'
},
key2: {
keyB: 'valueII'
},
key3: { a: { b: { c: 2 } } }
}, {
transformKey: function(key){
return '__' + key + '__';
}
})

// {
// '__key1__.__keyA__': 'valueI',
// '__key2__.__keyB__': 'valueII',
// '__key3__.__a__.__b__.__c__': 2
// }

unflatten({
'__key1__.__keyA__': 'valueI',
'__key2__.__keyB__': 'valueII',
'__key3__.__a__.__b__.__c__': 2
}, {
transformKey: function(key){
return key.substring(2, key.length - 2)
}
})

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

Command Line Usage

flat is also available as a command line tool. You can run it with npx:

`sh
npx flat foo.json
`

Or install the flat command globally:

`sh
npm i -g flat && flat foo.json
`

Accepts a filename as an argument:

`sh
flat foo.json
`

Also accepts JSON on stdin:

`sh
cat foo.json | flat
``