| Rfc | 6902 |
|---|
| Title | JavaScript Object Notation (JSON) Patch |
|---|
| Author | P. Bryan, Ed., M.
Nottingham, Ed. |
|---|
| Date | April 2013 |
|---|
| Format: | TXT, HTML |
|---|
| Status: | PROPOSED
STANDARD |
|---|
|
Internet Engineering Task Force (IETF) P. Bryan, Ed.
Request for Comments: 6902 Salesforce.com
Category: Standards Track M. Nottingham, Ed.
ISSN: 2070-1721 Akamai
April 2013
JavaScript Object Notation (JSON) Patch
Abstract
JSON Patch defines a JSON document structure for expressing a
sequence of operations to apply to a JavaScript Object Notation
(JSON) document; it is suitable for use with the HTTP PATCH method.
The "application/json-patch+json" media type is used to identify such
patch documents.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6902.
Copyright Notice
Copyright (c) 2013 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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Document Structure . . . . . . . . . . . . . . . . . . . . . . 3
4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. add . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. remove . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.3. replace . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.4. move . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.5. copy . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.6. test . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . . 10
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 12
A.1. Adding an Object Member . . . . . . . . . . . . . . . . . 12
A.2. Adding an Array Element . . . . . . . . . . . . . . . . . 12
A.3. Removing an Object Member . . . . . . . . . . . . . . . . 12
A.4. Removing an Array Element . . . . . . . . . . . . . . . . 13
A.5. Replacing a Value . . . . . . . . . . . . . . . . . . . . 13
A.6. Moving a Value . . . . . . . . . . . . . . . . . . . . . . 14
A.7. Moving an Array Element . . . . . . . . . . . . . . . . . 14
A.8. Testing a Value: Success . . . . . . . . . . . . . . . . . 15
A.9. Testing a Value: Error . . . . . . . . . . . . . . . . . . 15
A.10. Adding a Nested Member Object . . . . . . . . . . . . . . 15
A.11. Ignoring Unrecognized Elements . . . . . . . . . . . . . . 16
A.12. Adding to a Nonexistent Target . . . . . . . . . . . . . . 16
A.13. Invalid JSON Patch Document . . . . . . . . . . . . . . . 17
A.14. ~ Escape Ordering . . . . . . . . . . . . . . . . . . . . 17
A.15. Comparing Strings and Numbers . . . . . . . . . . . . . . 17
A.16. Adding an Array Value . . . . . . . . . . . . . . . . . . 18
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.
JSON Patch is a format (identified by the media type "application/
json-patch+json") for expressing a sequence of operations to apply to
a target JSON document; it is suitable for use with the HTTP PATCH
method.
This format is also potentially useful in other cases in which it is
necessary to make partial updates to a JSON document or to a data
structure that has similar constraints (i.e., they can be serialized
as an object or an array using the JSON grammar).
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 is a JSON [RFC4627] document that represents an
array of objects. Each object represents a single operation to be
applied to the target JSON document.
The following is an example JSON Patch document, transferred in an
HTTP PATCH request:
PATCH /my/data HTTP/1.1
Host: example.org
Content-Length: 326
Content-Type: application/json-patch+json
If-Match: "abc123"
[
{ "op": "test", "path": "/a/b/c", "value": "foo" },
{ "op": "remove", "path": "/a/b/c" },
{ "op": "add", "path": "/a/b/c", "value": [ "foo", "bar" ] },
{ "op": "replace", "path": "/a/b/c", "value": 42 },
{ "op": "move", "from": "/a/b/c", "path": "/a/b/d" },
{ "op": "copy", "from": "/a/b/d", "path": "/a/b/e" }
]
Evaluation of a JSON Patch document begins against 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 until an error condition is encountered.
4. Operations
Operation objects MUST have exactly one "op" member, whose value
indicates the operation to perform. Its value MUST be one of "add",
"remove", "replace", "move", "copy", or "test"; other values are
errors. The semantics of each object is defined below.
Additionally, operation objects MUST have exactly one "path" member.
That member's value is a string containing a JSON-Pointer value
[RFC6901] that references a location within the target document (the
"target location") where the operation is performed.
The meanings of other operation object members are defined by
operation (see the subsections below). Members that are not
explicitly defined for the operation in question MUST be ignored
(i.e., the operation will complete as if the undefined member did not
appear in the object).
Note that the ordering of members in JSON objects is not significant;
therefore, the following operation objects are equivalent:
{ "op": "add", "path": "/a/b/c", "value": "foo" }
{ "path": "/a/b/c", "op": "add", "value": "foo" }
{ "value": "foo", "path": "/a/b/c", "op": "add" }
Operations are applied to the data structures represented by a JSON
document, i.e., after any unescaping (see [RFC4627], Section 2.5)
takes place.
4.1. add
The "add" operation performs one of the following functions,
depending upon what the target location references:
o If the target location specifies an array index, a new value is
inserted into the array at the specified index.
o If the target location specifies an object member that does not
already exist, a new member is added to the object.
o If the target location specifies an object member that does exist,
that member's value is replaced.
The operation object MUST contain a "value" member whose content
specifies the value to be added.
For example:
{ "op": "add", "path": "/a/b/c", "value": [ "foo", "bar" ] }
When the operation is applied, the target location MUST reference one
of:
o The root of the target document - whereupon the specified value
becomes the entire content of the target document.
o A member to add to an existing object - whereupon the supplied
value is added to that object at the indicated location. If the
member already exists, it is replaced by the specified value.
o An element to add to an existing array - whereupon the supplied
value is added to the array at the indicated location. Any
elements at or above the specified index are shifted one position
to the right. The specified index MUST NOT be greater than the
number of elements in the array. If the "-" character is used to
index the end of the array (see [RFC6901]), this has the effect of
appending the value to the array.
Because this operation is designed to add to existing objects and
arrays, its target location will often not exist. Although the
pointer's error handling algorithm will thus be invoked, this
specification defines the error handling behavior for "add" pointers
to ignore that error and add the value as specified.
However, the object itself or an array containing it does need to
exist, and it remains an error for that not to be the case. For
example, an "add" with a target location of "/a/b" starting with this
document:
{ "a": { "foo": 1 } }
is not an error, because "a" exists, and "b" will be added to its
value. It is an error in this document:
{ "q": { "bar": 2 } }
because "a" does not exist.
4.2. remove
The "remove" operation removes the value at the target location.
The target location MUST exist for the operation to be successful.
For example:
{ "op": "remove", "path": "/a/b/c" }
If removing an element from an array, any elements above the
specified index are shifted one position to the left.
4.3. replace
The "replace" operation replaces the value at the target location
with a new value. The operation object MUST contain a "value" member
whose content specifies the replacement value.
The target location MUST exist for the operation to be successful.
For example:
{ "op": "replace", "path": "/a/b/c", "value": 42 }
This operation is functionally identical to a "remove" operation for
a value, followed immediately by an "add" operation at the same
location with the replacement value.
4.4. move
The "move" operation removes the value at a specified location and
adds it to the target location.
The operation object MUST contain a "from" member, which is a string
containing a JSON Pointer value that references the location in the
target document to move the value from.
The "from" location MUST exist for the operation to be successful.
For example:
{ "op": "move", "from": "/a/b/c", "path": "/a/b/d" }
This operation is functionally identical to a "remove" operation on
the "from" location, followed immediately by an "add" operation at
the target location with the value that was just removed.
The "from" location MUST NOT be a proper prefix of the "path"
location; i.e., a location cannot be moved into one of its children.
4.5. copy
The "copy" operation copies the value at a specified location to the
target location.
The operation object MUST contain a "from" member, which is a string
containing a JSON Pointer value that references the location in the
target document to copy the value from.
The "from" location MUST exist for the operation to be successful.
For example:
{ "op": "copy", "from": "/a/b/c", "path": "/a/b/e" }
This operation is functionally identical to an "add" operation at the
target location using the value specified in the "from" member.
4.6. test
The "test" operation tests that a value at the target location is
equal to a specified value.
The operation object MUST contain a "value" member that conveys the
value to be compared to the target location's value.
The target location MUST be equal to the "value" value for the
operation to be considered successful.
Here, "equal" means that the value at the target location and the
value conveyed by "value" are of the same JSON type, and that they
are considered equal by the following rules for that type:
o strings: are considered equal if they contain the same number of
Unicode characters and their code points are byte-by-byte equal.
o numbers: are considered equal if their values are numerically
equal.
o arrays: are considered equal if they contain the same number of
values, and if each value can be considered equal to the value at
the corresponding position in the other array, using this list of
type-specific rules.
o objects: are considered equal if they contain the same number of
members, and if each member can be considered equal to a member in
the other object, by comparing their keys (as strings) and their
values (using this list of type-specific rules).
o literals (false, true, and null): are considered equal if they are
the same.
Note that the comparison that is done is a logical comparison; e.g.,
whitespace between the member values of an array is not significant.
Also, note that ordering of the serialization of object members is
not significant.
For example:
{ "op": "test", "path": "/a/b/c", "value": "foo" }
5. Error Handling
If a normative requirement is violated by a JSON Patch document, or
if an operation is not successful, evaluation of the JSON Patch
document SHOULD terminate and application of the entire patch
document SHALL NOT be deemed successful.
See [RFC5789], Section 2.2 for considerations regarding handling
errors when JSON Patch is used with the HTTP PATCH method, including
suggested status codes to use to indicate various conditions.
Note that the HTTP PATCH method is atomic, as per [RFC5789].
Therefore, the following patch would result in no changes being made
to the document at all (because the "test" operation results in an
error):
[
{ "op": "replace", "path": "/a/b/c", "value": 42 },
{ "op": "test", "path": "/a/b/c", "value": "C" }
]
6. IANA Considerations
The Internet media type for a JSON Patch document is application/
json-patch+json.
Type name: application
Subtype name: json-patch+json
Required parameters: none
Optional parameters: none
Encoding considerations: binary
Security considerations:
See Security Considerations in Section 7.
Interoperability considerations: N/A
Published specification:
RFC 6902
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 <pbryan@anode.ca>
Intended usage: COMMON
Restrictions on usage: none
Author: Paul C. Bryan <pbryan@anode.ca>
Change controller: IETF
7. Security Considerations
This specification has the same security considerations as JSON
[RFC4627] and JSON-Pointer [RFC6901].
A few older Web browsers can be coerced into loading an arbitrary
JSON document whose root is an array, leading to a situation in which
a JSON Patch document containing sensitive information could be
exposed to attackers, even if access is authenticated. This is known
as a Cross-Site Request Forgery (CSRF) attack [CSRF].
However, such browsers are not widely used (at the time of writing,
it is estimated that they are used in less than 1% of the market).
Publishers who are nevertheless concerned about this attack are
advised to avoid making such documents available with HTTP GET.
8. Acknowledgements
The following individuals contributed ideas, feedback and wording to
this specification:
Mike Acar, Mike Amundsen, Cyrus Daboo, Paul Davis, Stefan Koegl,
Murray S. Kucherawy, Dean Landolt, Randall Leeds, James Manger,
Julian Reschke, James Snell, Eli Stevens, and Henry S. Thompson.
The structure of a JSON Patch document was influenced by the XML
Patch document specification [RFC5261].
9. References
9.1. Normative References
[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.
[RFC6901] Bryan, P., Ed., Zyp, K., and M. Nottingham, Ed.,
"JavaScript Object Notation (JSON) Pointer", RFC 6901,
April 2013.
9.2. Informative References
[CSRF] Barth, A., Jackson, C., and J. Mitchell, "Robust Defenses
for Cross-Site Request Forgery", ACM Conference
on Computer and Communications Security, October 2008,
<http://seclab.stanford.edu/websec/csrf/csrf.pdf>.
[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:
[
{ "op": "add", "path": "/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:
[
{ "op": "add", "path": "/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:
[
{ "op": "remove", "path": "/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:
[
{ "op": "remove", "path": "/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:
[
{ "op": "replace", "path": "/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:
[
{ "op": "move", "from": "/foo/waldo", "path": "/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:
[
{ "op": "move", "from": "/foo/1", "path": "/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 that will result in successful evaluation:
[
{ "op": "test", "path": "/baz", "value": "qux" },
{ "op": "test", "path": "/foo/1", "value": 2 }
]
A.9. Testing a Value: Error
An example target JSON document:
{ "baz": "qux" }
A JSON Patch document that will result in an error condition:
[
{ "op": "test", "path": "/baz", "value": "bar" }
]
A.10. Adding a Nested Member Object
An example target JSON document:
{ "foo": "bar" }
A JSON Patch document:
[
{ "op": "add", "path": "/child", "value": { "grandchild": { } } }
]
The resulting JSON document:
{
"foo": "bar",
"child": {
"grandchild": {
}
}
}
A.11. Ignoring Unrecognized Elements
An example target JSON document:
{ "foo": "bar" }
A JSON Patch document:
[
{ "op": "add", "path": "/baz", "value": "qux", "xyz": 123 }
]
The resulting JSON document:
{
"foo": "bar",
"baz": "qux"
}
A.12. Adding to a Nonexistent Target
An example target JSON document:
{ "foo": "bar" }
A JSON Patch document:
[
{ "op": "add", "path": "/baz/bat", "value": "qux" }
]
This JSON Patch document, applied to the target JSON document above,
would result in an error (therefore, it would not be applied),
because the "add" operation's target location that references neither
the root of the document, nor a member of an existing object, nor a
member of an existing array.
A.13. Invalid JSON Patch Document
A JSON Patch document:
[
{ "op": "add", "path": "/baz", "value": "qux", "op": "remove" }
]
This JSON Patch document cannot be treated as an "add" operation,
because it contains a later "op":"remove" element. JSON requires
that object member names be unique with a "SHOULD" requirement, and
there is no standard error handling for duplicates.
A.14. ~ Escape Ordering
An example target JSON document:
{
"/": 9,
"~1": 10
}
A JSON Patch document:
[
{"op": "test", "path": "/~01", "value": 10}
]
The resulting JSON document:
{
"/": 9,
"~1": 10
}
A.15. Comparing Strings and Numbers
An example target JSON document:
{
"/": 9,
"~1": 10
}
A JSON Patch document:
[
{"op": "test", "path": "/~01", "value": "10"}
]
This results in an error, because the test fails. The document value
is numeric, whereas the value being tested for is a string.
A.16. Adding an Array Value
An example target JSON document:
{ "foo": ["bar"] }
A JSON Patch document:
[
{ "op": "add", "path": "/foo/-", "value": ["abc", "def"] }
]
The resulting JSON document:
{ "foo": ["bar", ["abc", "def"]] }
Authors' Addresses
Paul C. Bryan (editor)
Salesforce.com
Phone: +1 604 783 1481
EMail: pbryan@anode.ca
Mark Nottingham (editor)
Akamai
EMail: mnot@mnot.net