Applications Area Working Group P. Bryan, Ed. Internet-Draft ForgeRock Intended status: Informational March 9, 2012 Expires: September 10, 2012 JSON Patch draft-ietf-appsawg-json-patch-01 Abstract JSON Patch defines the media type "application/json-patch", a JSON document structure for expressing a sequence of operations to apply to a JSON document. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 10, 2012. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Bryan Expires September 10, 2012 [Page 1] Internet-Draft JSON Patch March 2012 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Document Structure . . . . . . . . . . . . . . . . . . . . . . 3 4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4.1. add . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.2. remove . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.3. replace . . . . . . . . . . . . . . . . . . . . . . . . . 4 4.4. move . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.5. copy . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.6. test . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 9.1. Normative References . . . . . . . . . . . . . . . . . . . 8 9.2. Informative References . . . . . . . . . . . . . . . . . . 8 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 8 A.1. Adding an Object Member . . . . . . . . . . . . . . . . . 8 A.2. Adding an Array Element . . . . . . . . . . . . . . . . . 9 A.3. Removing an Object Member . . . . . . . . . . . . . . . . 9 A.4. Removing an Array Element . . . . . . . . . . . . . . . . 10 A.5. Replacing a Value . . . . . . . . . . . . . . . . . . . . 10 A.6. Moving a Value . . . . . . . . . . . . . . . . . . . . . . 11 A.7. Moving an Array Element . . . . . . . . . . . . . . . . . 11 A.8. Testing a Value: Success . . . . . . . . . . . . . . . . . 12 A.9. Testing a Value: Error . . . . . . . . . . . . . . . . . . 12 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12 Bryan Expires September 10, 2012 [Page 2] Internet-Draft JSON Patch March 2012 1. Introduction JavaScript Object Notation (JSON) [RFC4627] is a common format for the exchange and storage of structured data. HTTP PATCH [RFC5789] extends the Hypertext Transfer Protocol (HTTP) [RFC2616] with a method to perform partial modifications to resources. The JSON Patch media type "application/json-patch" is a JSON document structure for expressing a sequence of operations to apply to a target JSON document, suitable for use with the HTTP PATCH method. 2. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 3. Document Structure A JSON Patch document contains a JSON array of objects. Each object contains a single operation to apply to the target JSON document. An example JSON Patch document: [ { "test": "/a/b/c", "value": "foo" }, { "remove": "/a/b/c" }, { "add": "/a/b/c", "value": [ "foo", "bar" ] }, { "replace": "/a/b/c", "value": 42 }, { "move": "/a/b/c", "to": "/a/b/d" }, { "copy": "/a/b/c", "to": "/a/b/e" } ] Evaluation of a JSON Patch document begins with a target JSON document. Operations are applied sequentially in the order they appear in the array. Each operation in the sequence is applied to the target document; the resulting document becomes the target of the next operation. Evaluation continues until all operations are successfully applied or an error condition is encountered. 4. Operations The operation to perform is expressed in a member of the operation object. The name of the operation member is one of: "add", "remove", "replace", "move", "copy" or "test". The member value is a string Bryan Expires September 10, 2012 [Page 3] Internet-Draft JSON Patch March 2012 containing a [JSON-Pointer] value, which references the location within the target document to perform the operation. It is an error condition if an operation object contains no recognized operation member or more than one operation member. 4.1. add The "add" operation adds a new value at the specified location in the target document. The location must reference one of: the root of the target document, a member to add to an existing object, or an element to add to an existing array. The operation object contains a "value" member, which specifies the value to be added. Example: { "add": "/a/b/c", "value": [ "foo", "bar" ] } If the location references the root of the target document or a member of an existing object, it is an error condition if a value at the specified location already exists. If the location references an element of an existing array, any elements at or above the specified index are shifted one position to the right. It is an error condition if the specified index is greater than the number of elements in the array. 4.2. remove The "remove" operation removes the value at the specified location in the target document. Example: { "remove": "/a/b/c" } If removing an element from an array, any elements above the specified index are shifted one position to the left. It is an error condition if a value at the specified location does not exist. 4.3. replace The "replace" operation replaces the value at the specified location in the target document with a new value. The operation object contains a "value" member, which specifies the replacement value. Bryan Expires September 10, 2012 [Page 4] Internet-Draft JSON Patch March 2012 Example: { "replace": "/a/b/c", "value": 42 } This operation is functionally identical to expressing a "remove" operation for a value, followed immediately by an "add" operation at the same location with the replacement value. It is an error condition if a value at the specified location does not exist. 4.4. move The "move" operation removes the value at one location and adds it to another location in the target document. The operation object contains a "to" member, a string containing a JSON Pointer value, which references the location in the target document to add the value to. This location must reference one of: the member to add to an existing object, or an element to add to an existing array. Example: { "move": "/a/b/c", "to": "/a/b/d" } This operation is functionally identical to expressing a "remove" operation, followed immediately by an "add" operation at the new location with the value that was just removed. Moving a value to its current location can be safely ignored. If the location in the "to" member references a member of an existing object in the target document, it is an error condition if a value at the specified location already exists. If the location in the "to" member references an element of an existing array, any elements at or above the specified index are shifted one position to the right. It is an error condition if the specified index is greater than the number of elements in the array. 4.5. copy The "copy" operation copies the value at one location to another location in the target document. The operation object contains a "to" member, a string containing a JSON Pointer value, which references the location in the target document to add the value to. This location must reference one of: Bryan Expires September 10, 2012 [Page 5] Internet-Draft JSON Patch March 2012 the member to add to an existing object, or an element to add to an existing array. Example: { "copy": "/a/b/c", "to": "/a/b/e" } If the location in the "to" member references a member of an existing object in the target document, it is an error condition if a value at the specified location already exists. If the location in the "to" member references an element of an existing array, any elements at or above the specified index are shifted one position to the right. It is an error condition if the specified index is greater than the number of elements in the array. 4.6. test The "test" operation tests that a value at the specified location in the target document is equal to a specified value. The operation object contains a "value" member, which specifies the value to test for. If values are or contain objects or arrays, they must be identical (i.e. same order of elements, with the same values). Example: { "test": "/a/b/c", "value": "foo" } It is an error condition if the value at the specified location is not equal to the specified value. 5. Error Handling If an error condition occurs, evaluation of the JSON Patch document SHOULD terminate and application of the entire patch document SHALL NOT be deemed successful. 6. IANA Considerations The Internet media type for a JSON Patch document is application/ json-patch. Type name: application Bryan Expires September 10, 2012 [Page 6] Internet-Draft JSON Patch March 2012 Subtype name: json-patch Required parameters: none Optional parameters: none Encoding considerations: binary Security considerations: See Security Considerations in section 7. Interoperability considerations: N/A Published specification: [this memo] Applications that use this media type: Applications that manipulate JSON documents. Additional information: Magic number(s): N/A File extension(s): .json-patch Macintosh file type code(s): TEXT Person & email address to contact for further information: Paul C. Bryan Intended usage: COMMON Restrictions on usage: none Author: Paul C. Bryan Change controller: IETF 7. Security Considerations This specification has the same security considerations as JSON [RFC4627] and [JSON-Pointer]. 8. Acknowledgements The following individuals contributed ideas, feedback and wording, Bryan Expires September 10, 2012 [Page 7] Internet-Draft JSON Patch March 2012 which contributed to the content of this specification: Mike Acar, Mike Amundsen, Paul Davis, Murray S. Kucherawy, Dean Landolt, Randall Leeds, Mark Nottingham, Julian Reschke, Eli Stevens. The structure of a JSON Patch document was influenced by the XML Patch document [RFC5261] specification. 9. References 9.1. Normative References [JSON-Pointer] Bryan, P. and K. Zyp, "JSON Pointer", draft-ietf-appsawg-json-pointer-01 (work in progress), March 2012. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4627] Crockford, D., "The application/json Media Type for JavaScript Object Notation (JSON)", RFC 4627, July 2006. 9.2. Informative References [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. [RFC5261] Urpalainen, J., "An Extensible Markup Language (XML) Patch Operations Framework Utilizing XML Path Language (XPath) Selectors", RFC 5261, September 2008. [RFC5789] Dusseault, L. and J. Snell, "PATCH Method for HTTP", RFC 5789, March 2010. Appendix A. Examples A.1. Adding an Object Member An example target JSON document: { "foo": "bar" } Bryan Expires September 10, 2012 [Page 8] Internet-Draft JSON Patch March 2012 A JSON Patch document: [ { "add": "/baz", "value": "qux" } ] The resulting JSON document: { "baz": "qux", "foo": "bar" } A.2. Adding an Array Element An example target JSON document: { "foo": [ "bar", "baz" ] } A JSON Patch document: [ { "add": "/foo/1", "value": "qux" } ] The resulting JSON document: { "foo": [ "bar", "qux", "baz" ] } A.3. Removing an Object Member An example target JSON document: { "baz": "qux", "foo": "bar" } A JSON Patch document: [ { "remove": "/baz" } ] Bryan Expires September 10, 2012 [Page 9] Internet-Draft JSON Patch March 2012 The resulting JSON document: { "foo": "bar" } A.4. Removing an Array Element An example target JSON document: { "foo": [ "bar", "qux", "baz" ] } A JSON Patch document: [ { "remove": "/foo/1" } ] The resulting JSON document: { "foo": [ "bar", "baz" ] } A.5. Replacing a Value An example target JSON document: { "baz": "qux", "foo": "bar" } A JSON Patch document: [ { "replace": "/baz", "value": "boo" } ] The resulting JSON document: { "baz": "boo", "foo": "bar" } Bryan Expires September 10, 2012 [Page 10] Internet-Draft JSON Patch March 2012 A.6. Moving a Value An example target JSON document: { "foo": { "bar": "baz", "waldo": "fred" } "qux": { "corge": "grault" } } A JSON Patch document: [ { "move": "/foo/waldo", to: "/qux/thud" } ] The resulting JSON document: { "foo": { "bar": "baz" } "qux": { "corge": "grault", "thud": "fred" } } A.7. Moving an Array Element An example target JSON document: { "foo": [ "all", "grass", "cows", "eat" ] } A JSON Patch document: [ { "move": "/foo/1", "to": "/foo/3" } ] The resulting JSON document: Bryan Expires September 10, 2012 [Page 11] Internet-Draft JSON Patch March 2012 { "foo": [ "all", "cows", "eat", "grass" ] } A.8. Testing a Value: Success An example target JSON document: { "baz": "qux", "foo": [ "a", 2, "c" ] } A JSON Patch document, which will result in successful evaluation: [ { "test": "/baz", "value": "qux" }, { "test": "/foo/1", "value": 2 } ] A.9. Testing a Value: Error An example target JSON document: { "baz": "qux" } A JSON Patch document, which will result in an error condition: [ { "test": "/baz", "value": "bar" } ] Author's Address Paul C. Bryan (editor) ForgeRock Phone: +1 604 783 1481 Email: pbryan@anode.ca Bryan Expires September 10, 2012 [Page 12]