Internet Engineering Task Force P. Bryan, Ed.
Internet-Draft ForgeRock US, Inc.
Intended status: Informational December 4, 2011
Expires: June 6, 2012
JSON Patch
draft-pbryan-json-patch-04
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.
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Task Force (IETF). Note that other groups may also distribute
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This Internet-Draft will expire on June 6, 2012.
Copyright Notice
Copyright (c) 2011 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
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described in the Simplified BSD License.
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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. test . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . . 8
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 8
A.1. Adding an Object Member . . . . . . . . . . . . . . . . . 8
A.2. Adding an Array Element . . . . . . . . . . . . . . . . . 8
A.3. Removing an Object Member . . . . . . . . . . . . . . . . 9
A.4. Removing an Array Element . . . . . . . . . . . . . . . . 9
A.5. Replacing a Value . . . . . . . . . . . . . . . . . . . . 10
A.6. Moving a Value . . . . . . . . . . . . . . . . . . . . . . 10
A.7. Moving an Array Element . . . . . . . . . . . . . . . . . 11
A.8. Testing a Value: Success . . . . . . . . . . . . . . . . . 11
A.9. Testing a Value: Error . . . . . . . . . . . . . . . . . . 12
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
JavaScript Object Notation (JSON) [RFC4627] is a common format for
the exchange and storage of structured data. HTTP PATCH [RFC5789]
extends 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" }
]
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 apply is expressed in a member of the operation
object. The name of the operation member is one of: "add", "remove",
"replace", "move" or "test". The member value is a string containing
a [JSON Pointer], which references the location in the target
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document to apply the operation. It is an error condition if an
operation object contains no operation member, or more than one
operation member.
4.1. add
The "add" operation adds a new value to the target document at the
specified location. 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 in the target document at
the specified location.
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 in the target document at
the specified location with a new value. The operation object
contains a "value" member, which specifies the replacement value.
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Example:
{ "replace": "/a/b/c", "value": 42 }
This operation is 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 which references the location in the target document to
move 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 identical to expressing a "remove" operation,
followed immediately by an "add" operation at the new location with
the value that was just removed.
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. test
The "test" operation tests that a value in the target document at the
specified location is equal to a specified value. The operation
object contains a "value" member, which specifies the value to test
for.
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Example:
{ "test": "/a/b/c", value: "foo" }
It is an error condition if the value in the target document 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
Subtype name: json-patch
Required parameters: none
Optional parameters: none
Encoding considerations:
Per JSON [RFC4627]: 8bit if UTF-8; binary if UTF-16 or UTF-32.
Security considerations:
See Security Considerations in section 7.
Interoperability considerations: N/A
Published specification:
draft-pbryan-json-patch-04
Applications that use this media type:
Applications that manipulate JSON documents.
Additional information:
Magic number(s): N/A
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File extension(s): .json-patch
Macintosh file type code(s): TEXT
Person & email address to contact for further information:
Paul C. Bryan <paul.bryan@forgerock.com>
Intended usage: COMMON
Restrictions on usage: none
Author: Paul C. Bryan <paul.bryan@forgerock.com>
Change controller: Paul C. Bryan <paul.bryan@forgerock.com>
7. Security Considerations
This specification has the same security considerations as JSON
[RFC4627] and JSON Pointer [JSON Pointer].
8. Acknowledgements
The following individuals contributed ideas, feedback and wording,
which contributed to the content of this specification:
Mike Amundsen, Paul Davis, Dean Landolt, Randall Leeds, Mark
Nottingham, Julian Reschke, Eli Stevens.
The structure of a JSON Patch document was initially informed by the
XML Patch document [RFC5261] specification.
9. References
9.1. Normative References
[JSON Pointer]
Bryan, P. and K. Zyp, "JSON Pointer", October 2011, <http:
//tools.ietf.org/html/draft-pbryan-zyp-json-pointer-02>.
[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.
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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"
}
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:
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[
{ "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" }
]
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:
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{
"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"
}
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:
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{
"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:
{
"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 }
]
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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 US, Inc.
201 NE Park Plaza Drive Suite 196
Vancouver, WA 98684
USA
Phone: +1 604 783 1481
Email: paul.bryan@forgerock.com
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