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README.md

JSON-populate

npm version

Tool for populating JSON data with infinitely recursive circular references. Sort of like Falcor, but for plain JSON. It uses Proxy to lazily resolve relations where supported, otherwise there's a polyfill that uses an eager Object.assign approach (slow and very memory intensive if you populate more than a few levels - it's really just there for symbolic backwards compatibility)

Usage examples

Populating by naming convention:

/**
 * Import lib
 */
const { populateByConvention } = require('json-populate');

/**
 * Example data
 */
const stories = [
  {
    type: 'story',
    id: 'story-1',
    author: {
      person: 'person-1',
    },
  },
  {
    type: 'story',
    id: 'story-2',
    author: {
      person: 'person-2',
    },
  },
];

const people = [
  {
    type: 'person',
    id: 'person-1',
    name: 'John Storywriter',
    authored: {
      stories: ['story-1'],
    },
    likes: {
      stories: [
        'story-1',
        'story-2',
      ],
    }
  },
  {
    type: 'person',
    id: 'person-2',
    name: 'Peter Telltale',
    authored: {
      stories: ['story-2'],
    },
    likes: {
      stories: [
        'story-1',
        'story-2',
      ],
    }
  }
];

/**
 * Consolidate the collections into a "graph"
 */
const graph = { people, stories };

/**
 * Choose an entry point to the graph
 */
const entry = people[0];

/**
 * Create a populated entry point resolved against the graph with a specified depth
 */
const populatedItem = populateByConvention(2, graph, entry);

/**
 * Result
 */
console.log(JSON.stringify(populatedItem, null, 2));

/**
 * {
 *   "type": "person",
 *   "id": "person-1",
 *   "name": "John Storywriter",
 *   "authored": {
 *     "stories": [
 *       {
 *         "type": "story",
 *         "id": "story-1",
 *         "author": {
 *           "person": {
 *             "type": "person",
 *             "id": "person-1",
 *             "name": "John Storywriter",
 *             "authored": {
 *               "stories": [
 *                 "story-1"
 *               ]
 *             },
 *             "likes": {
 *               "stories": [
 *                 "story-1",
 *                 "story-2"
 *               ]
 *             }
 *           }
 *         }
 *       }
 *     ]
 *   },
 *   "likes": {
 *     "stories": [
 *       {
 *         "type": "story",
 *         "id": "story-1",
 *         "author": {
 *           "person": {
 *             "type": "person",
 *             "id": "person-1",
 *             "name": "John Storywriter",
 *             "authored": {
 *               "stories": [
 *                 "story-1"
 *               ]
 *             },
 *             "likes": {
 *               "stories": [
 *                 "story-1",
 *                 "story-2"
 *               ]
 *             }
 *           }
 *         }
 *       },
 *       {
 *         "type": "story",
 *         "id": "story-2",
 *         "author": {
 *           "person": {
 *             "type": "person",
 *             "id": "person-2",
 *             "name": "Peter Telltale",
 *             "authored": {
 *               "stories": [
 *                 "story-2"
 *               ]
 *             },
 *             "likes": {
 *               "stories": [
 *                 "story-1",
 *                 "story-2"
 *               ]
 *             }
 *           }
 *         }
 *       }
 *     ]
 *   }
 * }
 */

Populating by explicit reference:

/**
 * Import lib
 */
const { populateByReference } = require('json-populate');

/**
 * Example data
 */
const stories = [
  {
    type: 'story',
    id: 'story-1',
    author: { $ref: 'people', id: 'person-1' }
  },
  {
    type: 'story',
    id: 'story-2',
    author: { $ref: 'people', id: 'person-2' }
  },
];

const people = [
  {
    type: 'person',
    id: 'person-1',
    name: 'John Storywriter',
    authored: [
      { $ref: 'stories', id: 'story-1' },
    ],
    likes: [
      { $ref: 'stories', id: 'story-1' },
      { $ref: 'stories', id: 'story-2' },
    ],
  },
  {
    type: 'person',
    id: 'person-2',
    name: 'Peter Telltale',
    authored: [
      { $ref: 'stories', id: 'story-2' },
    ],
    likes: [
      { $ref: 'stories', id: 'story-1' },
      { $ref: 'stories', id: 'story-2' },
    ],
  }
];

/**
 * Consolidate the collections into a "graph"
 */
const graph = { people, stories };

/**
 * Choose an entry point to the graph
 */
const entry = people[0];

/**
 * Create a populated entry point resolved against the graph with a specified depth
 */
const populatedItem = populateByReference(2, graph, entry);

/**
 * Result
 */
console.log(JSON.stringify(populatedItem, null, 2));

/**
 * {
 *   "type": "person",
 *   "id": "person-1",
 *   "name": "John Storywriter",
 *   "authored": [
 *     {
 *       "type": "story",
 *       "id": "story-1",
 *       "author": {
 *         "type": "person",
 *         "id": "person-1",
 *         "name": "John Storywriter",
 *         "authored": [
 *           {
 *             "$ref": "stories",
 *             "id": "story-1"
 *           }
 *         ],
 *         "likes": [
 *           {
 *             "$ref": "stories",
 *             "id": "story-1"
 *           },
 *           {
 *             "$ref": "stories",
 *             "id": "story-2"
 *           }
 *         ]
 *       }
 *     }
 *   ],
 *   "likes": [
 *     {
 *       "type": "story",
 *       "id": "story-1",
 *       "author": {
 *         "type": "person",
 *         "id": "person-1",
 *         "name": "John Storywriter",
 *         "authored": [
 *           {
 *             "$ref": "stories",
 *             "id": "story-1"
 *           }
 *         ],
 *         "likes": [
 *           {
 *             "$ref": "stories",
 *             "id": "story-1"
 *           },
 *           {
 *             "$ref": "stories",
 *             "id": "story-2"
 *           }
 *         ]
 *       }
 *     },
 *     {
 *       "type": "story",
 *       "id": "story-2",
 *       "author": {
 *         "type": "person",
 *         "id": "person-2",
 *         "name": "Peter Telltale",
 *         "authored": [
 *           {
 *             "$ref": "stories",
 *             "id": "story-2"
 *           }
 *         ],
 *         "likes": [
 *           {
 *             "$ref": "stories",
 *             "id": "story-1"
 *           },
 *           {
 *             "$ref": "stories",
 *             "id": "story-2"
 *           }
 *         ]
 *       }
 *     }
 *   ]
 * }
 */

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Tool for populating JSON data with circular references. Sort of like Falcor and GraphQL, but for plain JSON with a transparent interface.

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