object-unpacker

TypeScript Object Unpacker

This program takes a JSON object and convertes it to a new JSON object using a mapping specification, also written as JSON.

There are some examples of how to use the mapper in the test directory, and a simple TypeScript example follows:

// Import the Schema Mapper type
import { createObjectUnpacker } from './ObjectUnpacker';

// Create the schema mapper
const mapper = createObjectUnpacker();

// This is the data to be transformed
const data = {
  "x": [
    {
      "a": [
        "testa",
        "testb"
      ],
      "au": "%system.metadata.author"
    }
  ]
};

// This is the transformation specification
const mapperData = {
  "x": {
    "rewriteKey": "expanded"
  },
  "a": {
    "rewriteKey": "another",
    "assignKeys": [
      "s",
      "t",
      "u"
    ],
    "rewriteValue": {
      "first": "%s",
      "second": "%t",
      "third": "%u",
      "fourth": "%/subs.system.metadata.name"
    }
  },
  "au": {
    "rewriteKey": "author"
  }
};

// Entries in this object can be referenced by the `data` or the `mapperData`.
// E.g. `%system.metadata.name` and '%system.metadata.author'
const refs = {
  system: {
    metadata: {
      name: 'The System Name',
      author: 'A. Programmer',
    },
  },
};

// Apply the mapping to the data to get an `expanded` object
const expanded: object = mapper.convert(refs, data, mapperData);

// Pretty-print the resulting JSON.
console.log(JSON.stringify(expanded, null, 2));

The same example in JavaScript

const unpacker = require("object-unpacker")

// This is the data to be transformed
const data = {
  "x": [
    {
      "a": [
        "testa",
        "testb"
      ],
      "au": "%system.metadata.author"
    }
  ]
};

// This is the transformation specification
const mapperData = {
  "x": {
    "rewriteKey": "expanded"
  },
  "a": {
    "rewriteKey": "another",
    "assignKeys": [
      "s",
      "t",
      "u"
    ],
    "rewriteValue": {
      "first": "%s",
      "second": "%t",
      "third": "%u",
      "fourth": "%/subs.system.metadata.name"
    }
  },
  "au": {
    "rewriteKey": "author"
  }
};

// Entries in this object can be referenced by the `data` or the `mapperData`.
// E.g. `%system.metadata.name` and '%system.metadata.author'
const refs = {
  system: {
    metadata: {
      name: 'The System Name',
      author: 'A. Programmer',
    },
  },
};

// Apply the mapping to the data to get an `expanded` object
const expanded = unpacker.mapper.convert(refs, data, mapperData);

// Pretty-print the resulting JSON.
console.log(JSON.stringify(expanded, null, 2));

Running the example code

1. Run npm install
2. Create scratch.ts in the src directory.
3. Compile it using the tsc command
4. Run it using node dist/scratch.js
5. Or combine the previous two steps as tsc && node dist/scratch.js

The output should look like this:

{
  "expanded": [
    {
      "another": {
        "first": "testa",
        "second": "testb",
        "fourth": "The System Name"
      },
      "author": "A. Programmer"
    }
  ]
}

Running the example code in a web browser

1. Run npm install
2. Run npm install -g webpack
3. Run npm install -g webpack-cli
4. Run the webpack command in the project root directory.
5. Open the test/index.html file using a web browser (Only tested using Brave browser)
6. Paste your JSON into the first two text areas and click Execute