sharp-pointer v0.1.0

sharp-pointer

A complete implementation of JSON Pointer (RFC 6901) for nodejs and modern browsers.

Install

npm install sharp-pointer

Use/Import

nodejs

var ptr = require('sharp-pointer')

Module API

Classes:

• JsonPointer : class – a convenience class for working with JSON pointers.
• JsonReference : class – a convenience class for working with JSON references.

Functions:

• .create(pointer)
• .has(target,pointer)
• .get(target,pointer)
• .set(target,pointer,value,force)
• .flatten(target,fragmentId)
• .list(target,fragmentId)
• .map(target,fragmentId)

All example code assumes data has this structure:

var data = {
  legumes: [{
    name: 'pinto beans',
    unit: 'lbs',
    instock: 4
  }, {
    name: 'lima beans',
    unit: 'lbs',
    instock: 21
  }, {
    name: 'black eyed peas',
    unit: 'lbs',
    instock: 13
  }, {
    name: 'plit peas',
    unit: 'lbs',
    instock: 8
  }]
}

.create(pointer)

Creates an instance of the JsonPointer class.

arguments:

• pointer : string, required – a JSON pointer in JSON string representation or URI fragment identifier representation

returns:

• a new JsonPointer instance

example:

var pointer = ptr.create('/legumes/0');
// fragmentId: #/legumes/0

.has(target,pointer)

Determins whether the specified target has a value at the pointer's path.

arguments:

• target : object, required – the target object
• pointer : string, required – a JSON pointer in JSON string representation or URI fragment identifier representation

returns:

• the dereferenced value or undefined if nonexistent

.get(target,pointer)

Gets a value from the specified target object at the pointer's path

arguments:

• target : object, required – the target object
• pointer : string, required – a JSON pointer in JSON string representation or URI fragment identifier representation

returns:

• the dereferenced value or undefined if nonexistent

example:

var value = ptr.get(data, '/legumes/1');
// fragmentId: #/legumes/1

.set(target, pointer, value, force)

Sets the value at the specified pointer on the target. The default behavior is to do nothing if pointer is nonexistent.

arguments:

• target : object, required – the target object
• pointer : string, required – a JSON pointer in JSON string representation or URI fragment identifier representation
• value : any – the value to be set at the specified pointer's path
• force : boolean, optional – indicates whether nonexistent paths are created during the call

returns:

• The prior value at the pointer's path — therefore, undefined means the pointer's path was nonexistent.

example:

var prior = ptr.set(data, '#/legumes/1/instock', 50);

example force:

var data = {};

ptr.set(data, '#/peter/piper', 'man', true);
ptr.set(data, '#/peter/pan', 'boy', true);
ptr.set(data, '#/peter/pickle', 'dunno', true);

console.log(JSON.stringify(data, null, '  '));

{
  "peter": {
    "piper": "man",
    "pan": "boy",
    "pickle": "dunno"
  }
}

.list(target, fragmentId)

Lists all of the pointers available on the specified target.

See a discussion about cycles in the object graph later in this document if you have interest in how such is dealt with.

arguments:

• target : object, required – the target object
• fragmentId : boolean, optional – indicates whether fragment identifiers should be listed instead of pointers

returns:

• an array of pointer-value pairs

example:

var list = ptr.list(data);

[ ...
  {
    "pointer": "/legumes/2/unit",
    "value": "ea"
  },
  {
    "pointer": "/legumes/2/instock",
    "value": 9340
  },
  {
    "pointer": "/legumes/3/name",
    "value": "plit peas"
  },
  {
    "pointer": "/legumes/3/unit",
    "value": "lbs"
  },
  {
    "pointer": "/legumes/3/instock",
    "value": 8
  }
]

fragmentId example:

var list = ptr.list(data, true);

[ ...
  {
    "fragmentId": "#/legumes/2/unit",
    "value": "ea"
  },
  {
    "fragmentId": "#/legumes/2/instock",
    "value": 9340
  },
  {
    "fragmentId": "#/legumes/3/name",
    "value": "plit peas"
  },
  {
    "fragmentId": "#/legumes/3/unit",
    "value": "lbs"
  },
  {
    "fragmentId": "#/legumes/3/instock",
    "value": 8
  }
]

.flatten(target, fragmentId)

Flattens an object graph (the target) into a single-level object of pointer-value pairs.

arguments:

• target : object, required – the target object
• fragmentId : boolean, optional – indicates whether fragment identifiers should be listed instead of pointers

returns:

• a flattened object of property-value pairs as properties.

example:

var obj = ptr.flatten(data, true);

{ ...
  "#/legumes/1/name": "lima beans",
  "#/legumes/1/unit": "lbs",
  "#/legumes/1/instock": 21,
  "#/legumes/2/name": "black eyed peas",
  "#/legumes/2/unit": "ea",
  "#/legumes/2/instock": 9340,
  "#/legumes/3/name": "plit peas",
  "#/legumes/3/unit": "lbs",
  "#/legumes/3/instock": 8
}

.map(target, fragmentId)

Flattens an object graph (the target) into a Map object.

arguments:

• target : object, required – the target object
• fragmentId : boolean, optional – indicates whether fragment identifiers should be listed instead of pointers

returns:

• a Map object containing key-value pairs where keys are pointers.

example:

var map = ptr.map(data, true);

for (let it of map) {
  console.log(JSON.stringify(it, null, '  '));
}

...
["#/legumes/0/name", "pinto beans"]
["#/legumes/0/unit", "lbs"]
["#/legumes/0/instock", 4 ]
["#/legumes/1/name", "lima beans"]
["#/legumes/1/unit", "lbs"]
["#/legumes/1/instock", 21 ]
["#/legumes/2/name", "black eyed peas"]
["#/legumes/2/unit", "ea"]
["#/legumes/2/instock", 9340 ]
["#/legumes/3/name", "plit peas"]
["#/legumes/3/unit", "lbs"]
["#/legumes/3/instock", 8 ]

.decode(pointer)

Decodes the specified pointer.

arguments:

• pointer : string, required – a JSON pointer in JSON string representation or URI fragment identifier representation.

returns:

• An array of path segments used as indexers to descend from a root/target object to a referenced value.

example:

var path = ptr.decode('#/legumes/1/instock');

[ "legumes", "1", "instock" ]

.decodePointer(pointer)

Decodes the specified pointer.

arguments:

• pointer : string, required – a JSON pointer in JSON string representation.

returns:

• An array of path segments used as indexers to descend from a root/target object to a referenced value.

example:

var path = ptr.decodePointer('/people/wilbur dongleworth/age');

[ "people", "wilbur dongleworth", "age" ]

.encodePointer(path)

Encodes the specified path as a JSON pointer in JSON string representation.

arguments:

• path : Array, required – an array of path segments

returns:

• A JSON pointer in JSON string representation.

example:

var path = ptr.encodePointer(['people', 'wilbur dongleworth', 'age']);

"/people/wilbur dongleworth/age"

.decodeUriFragmentIdentifier(pointer)

Decodes the specified pointer.

arguments:

• pointer : string, required – a JSON pointer in URI fragment identifier representation.

returns:

• An array of path segments used as indexers to descend from a root/target object to a referenced value.

example:

var path = ptr.decodePointer('#/people/wilbur%20dongleworth/age');

[ "people", "wilbur dongleworth", "age" ]

.encodeUriFragmentIdentifier(path)

Encodes the specified path as a JSON pointer in URI fragment identifier representation.

arguments:

• path : Array, required - an array of path segments

returns:

• A JSON pointer in URI fragment identifier representation.

example:

var path = ptr.encodePointer(['people', 'wilbur dongleworth', 'age']);

"#/people/wilbur%20dongleworth/age"

.noConflict()

Restores a conflicting JsonPointer variable in the global/root namespace (not necessary in node, but useful in browsers).

example:

	<!-- ur codez -->
	<script src="/json-ptr-0.3.0.min.js"></script>
	<script>
		// At this point, JsonPointer is the json-ptr module
		var ptr = JsonPointer.noConflict();
		// and now it is restored to whatever it was before the json-ptr import.
	</script>

JsonPointer Class

Encapsulates pointer related operations for a specified pointer.

properties:

• .path : array – contains the pointer's path segements.
• .pointer : string – the pointer's JSON string representation
• .uriFragmentIdentifier : string – the pointer's URI fragment identifier representation

methods:

.has(target)

Determins whether the specified target has a value at the pointer's path.

.get(target)

Looks up the specified target's value at the pointer's path if such exists; otherwise undefined.

.set(target, value, force)

Sets the specified target's value at the pointer's path, if such exists.If force is specified (truthy), missing path segments are created and the value is always set at the pointer's path.

arguments:

• target : object, required – the target object
• value : any – the value to be set at the specified pointer's path
• force : boolean, optional – indicates whether nonexistent paths are created during the call

result:

• The prior value at the pointer's path — therefore, undefined means the pointer's path was nonexistent.

Tests

Tests are written using mocha and expect.js.

npm test

... or ...

mocha

License

MIT