Take a nested Javascript object and flatten it, or unflatten an object with delimited keys
npm install @mongodb-js/flatOriginal flat package: (https://github.com/hughsk/flat)[https://github.com/hughsk/flat]
Forked to pull in changes in https://github.com/cipacda/flat (ignoreValue)
Take a nested Javascript object and flatten it, or unflatten an object with
delimited keys.
`` bash`
$ npm install flat
Flattens the object - it'll return an object one level deep, regardless of how
nested the original object was:
` javascript
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
// }
`
Flattening is reversible too, you can call flatten.unflatten() on an object:
` javascript
var unflatten = require('flat').unflatten
unflatten({
'three.levels.deep': 42,
'three.levels': {
nested: true
}
})
// {
// three: {
// levels: {
// deep: 42,
// nested: true
// }
// }
// }
`
Use a custom delimiter for (un)flattening your objects, instead of ..
When enabled, both flat and unflatten will preserve arrays and their
contents. This is disabled by default.
` javascript
var flatten = require('flat')
flatten({
this: [
{ contains: 'arrays' },
{ preserving: {
them: 'for you'
}}
]
}, {
safe: true
})
// {
// 'this': [
// { contains: 'arrays' },
// { preserving: {
// them: 'for you'
// }}
// ]
// }
`
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' }
// }
`
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.
Maximum number of nested objects to flatten.
` javascript
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 } }
// }
`
Transform each part of a flat key before and after flattening.
`javascript
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 } } }
// }
`
Ignore specific values from flattening.
`javascript
var flatten = require('flat')
var unflatten = require('flat').unflatten
flatten({
key1: {
keyA: 'valueI'
},
key2: {
keyB: 'valueII'
},
key3: { a: { b: { c: 2 } } }
}, {
ignoreValue: function(value){
return !!value.c;
}
})
// {
// 'key1.keyA': 'valueI',
// 'key2.keyB__': 'valueII',
// 'key3.a.b': {'c':2},
// }
`
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