@tromkom/aurora-strategic-json-merge-patch

Aurora Strategic JSON Merge

Aurora Strategic JSON Merge allows diffing and merging of objects, including array entries, however each array entry needs to have an object with a key attribute to serve as a unique identifier.

Installation

npm install @tromkom/aurora-strategic-json-merge-patch

Usage

The key attribute should always be a string

Diffing

Diffs two objects and returns an array of patches

const { diff } = require("aurora-strategic-json-merge-patch");

let base = [
  {
    id: "1",
    val: 123,
    arr: [
      {
        id: "1",
        val: 1,
      },
    ],
  },
  {
    id: "2",
    val: 456,
  },
];

let newBase = [
  {
    id: "1",
    val: 456,
    arr: [
      {
        id: "1",
        val: 1,
      },
      {
        id: "2",
        val: 222,
      },
    ],
  },
];

let patches = diff(base, newBase, "id");
console.log(patches);
/*
[
  { id: '1', val: 456, arr: [ { id: '2', val: 222 } ] },
  { id: '2', __self: null }
]
*/

Patching

Using the patch from diffing on an equal base object, will return the new base.

const { patch } = require("@tromkom/aurora-strategic-json-merge-patch");

let base = [
  {
    id: "1",
    val: 123,
    arr: [
      {
        id: "1",
        val: 1,
      },
    ],
  },
  {
    id: "2",
    val: 456,
  },
];

let patches = [
  { id: "1", val: 456, arr: [{ id: "2", val: 222 }] },
  { id: "2", __self: null },
];

let newBase = patch(base, patches, "id");
console.log(newBase);
/*
[
  {
    id: '1',
    val: 456,
    arr: [ { id: '1', val: 1 }, { id: '2', val: 222 } ]
  }
]
*/

Http/JSON Patching

If you want to use JSON patch you can do that.

Be careful when using JSON patch as the patch will use the "key" as opposed to the index of the array

const { httpPatch } = require("@tromkom/aurora-strategic-json-merge-patch");

let base = [
  {
    id: "1",
    val: 123,
    arr: [
      {
        id: "1",
        val: 1,
      },
    ],
  },
  {
    id: "2",
    val: 456,
  },
];

let patches = [
  { id: "1", val: 456, arr: [{ id: "2", val: 222 }] },
  { id: "2", __self: null },
];

let httpPatches = base
  .map((x) => httpPatch(x, patches, "id", `/${x.id}`).body)
  .flat();
console.log(httpPatches);
/*
[
  { op: 'replace', path: '/1/val', value: 456 },
  { path: '/1/arr/2', op: 'add', value: { id: '2', val: 222 } },
  { path: '/2', op: 'remove' }
]
*/

Merging

Does a strategic JSON Merge that will properly handle arrays (assuming they have a "key").

const { merge } = require("@tromkom/aurora-strategic-json-merge-patch");

let base = [
  {
    id: "1",
    val: 123,
    arr: [
      {
        id: "1",
        val: 1,
      },
    ],
  },
  {
    id: "2",
    val: 456,
  },
];

let newBase = [
  {
    id: "1",
    val: 456,
    arr: [
      {
        id: "2",
        val: 222,
      },
    ],
  },
];

let res = merge(base, newBase, "id");
console.log(res);
/*
[
  {
    id: '1',
    val: 456,
    arr: [ { id: '1', val: 1 }, { id: '2', val: 222 } ]
  },
  { id: '2', val: 456 }
]
*/