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

1$ 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:

1var flatten = require('flatley')
2
3flatten({
4    key1: {
5        keyA: 'valueI'
6    },
7    key2: {
8        keyB: 'valueII'
9    },
10    key3: { a: { b: { c: 2 } } }
11})
12
13// {
14//   'key1.keyA': 'valueI',
15//   'key2.keyB': 'valueII',
16//   'key3.a.b.c': 2
17// }

unflatten(original, options)

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

1var unflatten = require('flatley').unflatten
2
3unflatten({
4    'three.levels.deep': 42,
5    'three.levels': {
6        nested: true
7    }
8})
9
10// {
11//     three: {
12//         levels: {
13//             deep: 42,
14//             nested: true
15//         }
16//     }
17// }

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.

1var flatten = require('flatley')
2
3flatten({
4    this: [
5        { contains: 'arrays' },
6        { preserving: {
7              them: 'for you'
8        }}
9    ]
10}, {
11    safe: true
12})
13
14// {
15//     'this': [
16//         { contains: 'arrays' },
17//         { preserving: {
18//             them: 'for you'
19//         }}
20//     ]
21// }

object

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

1unflatten({
2    'hello.you.0': 'ipsum',
3    'hello.you.1': 'lorem',
4    'hello.other.world': 'foo'
5}, { object: true })
6
7// hello: {
8//     you: {
9//         0: 'ipsum',
10//         1: 'lorem',
11//     },
12//     other: { world: 'foo' }
13// }

overwrite

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

1unflatten({
2    'TRAVIS': 'true',
3    'TRAVIS_DIR': '/home/travis/build/kvz/environmental'
4}, { overwrite: true })
5
6// TRAVIS: {
7//     DIR: '/home/travis/build/kvz/environmental'
8// }

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.

1var flatten = require('flatley')
2
3flatten({
4    key1: {
5        keyA: 'valueI'
6    },
7    key2: {
8        keyB: 'valueII'
9    },
10    key3: { a: { b: { c: 2 } } }
11}, { maxDepth: 2 })
12
13// {
14//   'key1.keyA': 'valueI',
15//   'key2.keyB': 'valueII',
16//   'key3.a': { b: { c: 2 } }
17// }

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

1var ObjectId = mongoose.Types.ObjectId
2
3var coercion = [{
4    test: function (key, value) { return key === '_id' && ObjectId.isValid(value) }
5    transform: function (value) { return value.valueOf() }
6}]
7var options = { coercion: coercion }
8
9flatten({
10    group1: {
11        prop1: ObjectId('aaabbbcccdddeee')
12    }
13}, options)
14
15// {
16//    'group1.prop1': 'aaabbbcccdddeee'
17// }

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.

1
2const someObject = {
3    prop1: 'abc',
4    prop2: 'def'
5}
6
7var filters = [{
8    test: function (key, value) { return value.prop1 === 'abc' }
9}]
10var options = { filters: filters }
11
12flatten({
13    group1: {
14        someObject: someObject
15    }
16}, options)
17
18// {
19//    'group1.someObject': {
20//      'prop1': 'abc',
21//      'prop2': 'def'
22//    }
23// }