jolt-js

JSON to JSON transformation library using the JOLT spec.

TypeScript port of harmony-jolt, which itself is a port of the Java Jolt library.

Installation

npm install jolt-js

Usage

import { transform, TransformSpec } from 'jolt-js';

const input = {
  id: 1,
  name: "John Smith",
  account: {
    id: 1000,
    type: "Checking"
  }
};

const spec: TransformSpec = [
  {
    operation: "shift",
    spec: {
      name: "data.name",
      account: "data.account"
    }
  }
];

const output = transform(input, spec);
// {
//   data: {
//     name: "John Smith",
//     account: { id: 1000, type: "Checking" }
//   }
// }

Supported Operations

1. shift

Copy data from the input tree and put it in the output tree.

{
  operation: "shift",
  spec: {
    "name": "data.name",
    "*": "data.&"  // Wildcard matching
  }
}

Wildcards

• * - match everything
• name1|name2|nameN - match any of the specified names

Special Characters

• & - reference matched key from path (&(x,y) for specific level/match)
• $ - reference key value
• @ - reference data value at path
• [] - array index notation

2. default

Apply default values if not present in the input.

{
  operation: "default",
  spec: {
    "phones": {
      "code": "+1"
    }
  }
}

3. remove

Remove data from the tree.

{
  operation: "remove",
  spec: {
    "phones": {
      "country": ""
    }
  }
}

4. modify-overwrite-beta

Modify data using functions.

{
  operation: "modify-overwrite-beta",
  spec: {
    "fullName": "=concat(@(1,firstName),' ',@(1,lastName))"
  }
}

Supported Functions

• concat - Concatenate multiple strings
• toLower - Convert string to lowercase
• toUpper - Convert string to uppercase
• substring - Extract substring (start, end)
• trim - Remove leading/trailing whitespace
• join - Join array elements with separator

Modifier Variants

• modify-overwrite-beta - Always writes the result
• modify-default-beta - Only writes if key doesn't exist
• modify-define-beta - Only writes if key doesn't exist or is null

License

Apache-2.0