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https://github.com/panosoft/flattotrees
Utility to convert flat data into hierarchical data. In particular, data returned from a SQL query.
https://github.com/panosoft/flattotrees
Last synced: about 2 months ago
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Utility to convert flat data into hierarchical data. In particular, data returned from a SQL query.
- Host: GitHub
- URL: https://github.com/panosoft/flattotrees
- Owner: panosoft
- Created: 2016-05-23T17:28:35.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2016-06-09T19:53:40.000Z (over 8 years ago)
- Last Synced: 2024-08-09T21:26:50.011Z (5 months ago)
- Language: JavaScript
- Size: 5.86 KB
- Stars: 4
- Watchers: 5
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# flatToTrees
Utility to convert flat data into hierarchical data. In particular, data returned from a SQL query.
This library was inspired by [`treeize`](https://www.npmjs.com/package/treeize) which removes duplicate leaves. `flatToTrees` can do this but is **NOT** the default behavior.
[`treeize`](https://www.npmjs.com/package/treeize) also doesn't work well with heterogenous records, i.e. records that have different columns and names. (This is less aggregious than the removal of duplicate leaves)
[](https://travis-ci.org/panosoft/flatToTrees)
## Installation
```sh
npm install flatToTrees
```
## Usage
```js
flatToTrees(obj, options)
```
__Arguments__
- `obj` - An object.
- `options`:
- `delimiter` - (default: `.`) Path delimiter that defines the hierarchy.
- `removeDuplicateLeaves` - (default: `false`) Flag to remove duplicate leaves in the trees.
__Example__
```js
const flatToTrees = require('flatToTrees');
const o = [
{a: 1, 'xs.b': 2, 'xs.x': 10, 'xs.cs.d': 3, 'ys.g': 12, 'ys.h': 20},
{a: 1, 'xs.b': 2, 'xs.x': 10, 'xs.cs.d': 3, 'ys.g': 12, 'ys.h': 21},
];
const trees = flatToTrees(o);
/*
trees === [ { a: 1,
xs: [ { b: 2, cs: [ { d: 3 }, { d: 3 } ], x: 10 } ],
ys: [ { g: 12, h: 20 }, { g: 12, h: 21 } ] } ]
*/
```
If `removeDuplicateLeaves` was set to `true` in the `options` parameter, then:
```js
/*
trees === [ { a: 1,
xs: [ { b: 2, cs: [ { d: 3 } ], x: 10 } ],
ys: [ { g: 12, h: 20 }, { g: 12, h: 21 } ] } ]
*/
```
Notice that `trees.xs.cs` has only one copy of `{d: 3}`.
For more examples, see the test code.
## Details
Flat data like data from a SQL query can have duplicate information especially when JOINs are used. `flatToTrees` will take an `array` of `objects` and combine any keys of the form:
```
.....
```
Here the delimiter is the default of `.`. `` through `` will be arrays in the form:
```
...
```
Any key's that are of the form:
```
```
will be used to combine like records. In the above [`example`](#example), the flat data has `a` = `1` for **both** records. This is why they are combined into a **single** hierarchy.
The combination logic is repeated at every level of arrays until the `` is reached where it's simply added to the end of the final array.
In the above [`example`](#example), `xs.cs` implies the following hierarchy:
```js
xs: [
cs: [
// objects go here
]
]
```
And `xs.cs.d`, is placed in the hierarchy like:
```js
xs: [
cs: [
{d: 3}
]
]
```
If you're coming to this library from [`treeize`](https://www.npmjs.com/package/treeize), it's **IMPORTANT** to note that there is **NO** naming convention on keys as is true with [`treeize`](https://www.npmjs.com/package/treeize).
Prefixes to keys, i.e. `` through `` will be considered arrays.
Although this library was originally developed with SQL data in mind, which will guarantee that **every column has the same name for each record** and **each record has every column**, i.e. homogenous data, the library works as expected when **neither is true**. The usefulness of such a scenario is debatable, nonetheless, it still works well.