threeWayMerge#

The threeWayMerge function performs a three-way merge on two JSON objects (left and right) with a common ancestor (base). It identifies and resolves conflicts between the changes made in the left and right JSON objects. If conflicts are detected, the method returns the conflict paths; otherwise, it merges the changes and returns the resulting JSON object.

Types#

PathType#

The PathType type represents the path to a value within a JSON object or array. It can be either a string (for object keys) or a number (for array indices). This type is used to specify the location of conflicts within the JSON structure.

type PathType = string | number;

Patch Options#

The patchOptions object is used to configure the merge behavior for arrays. In this example, deepPatch is set to true to enable deep patching for arrays.

const patchOptions = { arrays: { deepPatch: true } };

Function Signature#

const threeWayMerge: (base: Json, left: Json, right: Json) => ThreeWayMergeResult;

Parameters#

• base (Json): The common ancestor JSON object.
• left (Json): The first JSON object with changes.
• right (Json): The second JSON object with changes.

Return Value#

The method returns a ThreeWayMergeResult object:

• conflict (boolean): Indicates if there are conflicts.
• result (Json | null): The merged JSON object if no conflicts are found, otherwise null.
• conflicts (PathType[][]): An array of conflict paths if conflicts are found.

Usage#

import { threeWayMerge } from 'jsoncargo';

const base = { a: 1, b: 2 };
const left = { a: 1, b: 3 };
const right = { a: 1, b: 4 };

const result = threeWayMerge(base, left, right);

if (result.conflict) {
  console.log('Conflicts found:', result.conflicts);
} else {
  console.log('Merged result:', result.result);
}

The threeWayMerge function helps to merge changes from two JSON objects with a common ancestor. It generates patches for both the left and right JSON objects based on the base, identifies any conflicts between these patches, and merges them if no conflicts are found. The function returns a result indicating whether conflicts were found and, if not, the merged JSON object.