JarCastingflat 
Take a nested Javascript object and flatten it, or unflatten an object with delimited keys.
Installation
$ npm install flat
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('flat')
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('flat').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('flat')
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('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 } }
// }
transformKey
Transform each part of a flat key before and after flattening.
var flatten = require('flat')
var unflatten = require('flat').unflatten
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:
npx flat foo.json
Or install the flat command globally:
npm i -g flat && flat foo.json
Accepts a filename as an argument:
flat foo.json
Also accepts JSON on stdin:
cat foo.json | flat