willyboy / jsonpath-object-transform

Transform an object literal using JSONPath.

jsonpath-object-transform

Transform an object literal using JSONPath.

Pulls data from an object literal using JSONPath and generate a new object based on a template. Each of the template's properties can pull a single property from the source data or an array of all results found by its JSONPath. When pulling an array of data you can also supply a subtemplate to transform each item in the array. Both keys and values will be interpolated.

JSONPath is like XPath for JavaScript objects. To learn the syntax, read the documentation for the JSONPath package on npm and the original article by Stefan Goessner.

Usage

var transform = require('jsonpath-object-transform');

var template = {
  foo: ['$.some.crazy', {
    bar: '$.example'
  }]
};

var data = {
  some: {
    crazy: [
      {
        example: 'A'
      },
      {
        example: 'B'
      }
    ]
  }
};

var result = transform(data, template);

Result:

{
  foo: [
    {
      bar: 'A'
    },
    {
      bar: 'B'
    }
  ]
}

Method

jsonPathObjectTransform(data, template);

Where data and template are both a plain Object. Returns the transformed Object.

Template Objects

Your template will be an object literal that outlines what the resulting object should look like. Each property will contain a JSONPath String or Array depending on how many properties from the source data you want to assign to the generated object.

Pulling a Single Property

{ destination: '$.path.to.source' }

Use a String on your template property to assign a single object returned from your JSONPath. If your path returns multiple results then only the first is used.

Example

var template = {
  foo: '$.example'
};

var data = {
  example: 'bar'
};

Result:

{
  foo: 'bar'
}

Pulling an Array of Properties

{ destination: ['$.path.to.sources'] }

Use an Array containing a single String to assign all results returned from your JSONPath.

Example

var template = {
  foo: ['$..example']
};

var data = {
  a: {
    example: 'bar'
  },
  b: {
    example: 'baz'
  }
};

Result:

{
  foo: ['bar', 'baz']
}

Transform Items Returned in Array

{ destination: ['$.path.to.sources', { item: '$.item.path' }] }

Use an Array with a String and an Object to assign all results returned from your JSONPath and transform each of the objects with a subtemplate.

Example

var template = {
  foo: ['$..example', {
    bar: '$.demo'
  }]
};

var data = {
  a: {
    example: {
      demo: 'baz'
    }
  },
  b: {
    example: {
      demo: 'qux'
    }
  }
};

Result:

{
  foo: [
    { bar: 'baz' },
    { bar: 'qux' }
  ]
}

Merge Items Returned in Array into a single object

{ destination: ['$.path.to.sources', { '$.item.key': '$.item.path' }, {merge: true}] }

Use an Array with a String and an Object to assign all results returned from your JSONPath and transform each of the objects with a subtemplate. The "merge: true" option will merge the results into one object. e.g.

[{a:'b'},{c:'d'},{e:'f'}]

->

{a:'b',c:'d',e:'f'}

Example

var template = {
  foo: ['$..example', {
    '$.key': '$.demo'
  }, {merge: true}]
};

var data = {
  a: {
    example: {
      key: 'a',
      demo: 'baz'
    }
  },
  b: {
    // NOTE: you can use arrays or objects in this example and the previous one
    example: [{
      key: 'b',
      demo: 'qux'
    },{
      key: 'c',
      demo: 'max'
    }]
  }
};

Result:

{
  foo: { 
    a: 'baz',
    b: 'qux',
    c: 'max'
  }
}

Dynamic Keys

{ '$.aKey': ['$.path.to.sources', { '$.item.key': '$.item.path' }] }

Use any valid JSON path as the key to assign a dynamic key to your result object

Example

var template = {
  '$.a.example.demo': ['$..example', {
    '$.key': '$.demo'
  }, {merge: true}]
};

var data = {
  a: {
    example: {
      key: 'a',
      demo: 'baz'
    }
  },
  b: {
    // NOTE: you can use arrays or objects in this example and the previous one
    example: [{
      key: 'b',
      demo: 'qux'
    },{
      key: 'c',
      demo: 'max'
    }]
  }
};

Result:

{
  "baz": {
    "a": "baz",
    "b": "qux",
    "c": "max"
  }
}