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README
¶
JSON-Patch
jsonpatch is a library which provides functionallity for both applying
RFC6902 JSON patches against documents, as
well as for calculating & applying RFC7396 JSON merge patches.
Get It!
Latest and greatest:
go get -u github.com/evanphx/json-patch
Stable Versions:
- Version 4:
go get -u gopkg.in/evanphx/json-patch.v4
(previous versions below v3 are unavailable)
Use It!
- Create and apply a merge patch
- Create and apply a JSON Patch
- Comparing JSON documents
- Combine merge patches
Configuration
There is a single global configuration variable jsonpatch.SupportNegativeIndices'. This defaults to trueand enables the non-standard practice of allowing negative indices to mean indices starting at the end of an array. This functionality can be disabled by settingjsonpatch.SupportNegativeIndices = false`.
Create and apply a merge patch
Given both an original JSON document and a modified JSON document, you can create a Merge Patch document.
It can describe the changes needed to convert from the original to the modified JSON document.
Once you have a merge patch, you can apply it to other JSON documents using the
jsonpatch.MergePatch(document, patch) function.
package main
import (
"fmt"
jsonpatch "github.com/evanphx/json-patch"
)
func main() {
// Let's create a merge patch from these two documents...
original := []byte(`{"name": "John", "age": 24, "height": 3.21}`)
target := []byte(`{"name": "Jane", "age": 24}`)
patch, err := jsonpatch.CreateMergePatch(original, target)
if err != nil {
panic(err)
}
// Now lets apply the patch against a different JSON document...
alternative := []byte(`{"name": "Tina", "age": 28, "height": 3.75}`)
modifiedAlternative, err := jsonpatch.MergePatch(alternative, patch)
fmt.Printf("patch document: %s\n", patch)
fmt.Printf("updated alternative doc: %s\n", modifiedAlternative)
}
When ran, you get the following output:
$ go run main.go
patch document: {"height":null,"name":"Jane"}
updated tina doc: {"age":28,"name":"Jane"}
Create and apply a JSON Patch
You can create patch objects using DecodePatch([]byte), which can then
be applied against JSON documents.
The following is an example of creating a patch from two operations, and applying it against a JSON document.
package main
import (
"fmt"
jsonpatch "github.com/evanphx/json-patch"
)
func main() {
original := []byte(`{"name": "John", "age": 24, "height": 3.21}`)
patchJSON := []byte(`[
{"op": "replace", "path": "/name", "value": "Jane"},
{"op": "remove", "path": "/height"}
]`)
patch, err := jsonpatch.DecodePatch(patchJSON)
if err != nil {
panic(err)
}
modified, err := patch.Apply(original)
if err != nil {
panic(err)
}
fmt.Printf("Original document: %s\n", original)
fmt.Printf("Modified document: %s\n", modified)
}
When ran, you get the following output:
$ go run main.go
Original document: {"name": "John", "age": 24, "height": 3.21}
Modified document: {"age":24,"name":"Jane"}
Comparing JSON documents
Due to potential whitespace and ordering differences, one cannot simply compare JSON strings or byte-arrays directly.
As such, you can instead use jsonpatch.Equal(document1, document2) to
determine if two JSON documents are structurally equal. This ignores
whitespace differences, and key-value ordering.
package main
import (
"fmt"
jsonpatch "github.com/evanphx/json-patch"
)
func main() {
original := []byte(`{"name": "John", "age": 24, "height": 3.21}`)
similar := []byte(`
{
"age": 24,
"height": 3.21,
"name": "John"
}
`)
different := []byte(`{"name": "Jane", "age": 20, "height": 3.37}`)
if jsonpatch.Equal(original, similar) {
fmt.Println(`"original" is structurally equal to "similar"`)
}
if !jsonpatch.Equal(original, different) {
fmt.Println(`"original" is _not_ structurally equal to "similar"`)
}
}
When ran, you get the following output:
$ go run main.go
"original" is structurally equal to "similar"
"original" is _not_ structurally equal to "similar"
Combine merge patches
Given two JSON merge patch documents, it is possible to combine them into a single merge patch which can describe both set of changes.
The resulting merge patch can be used such that applying it results in a document structurally similar as merging each merge patch to the document in succession.
package main
import (
"fmt"
jsonpatch "github.com/evanphx/json-patch"
)
func main() {
original := []byte(`{"name": "John", "age": 24, "height": 3.21}`)
nameAndHeight := []byte(`{"height":null,"name":"Jane"}`)
ageAndEyes := []byte(`{"age":4.23,"eyes":"blue"}`)
// Let's combine these merge patch documents...
combinedPatch, err := jsonpatch.MergeMergePatches(nameAndHeight, ageAndEyes)
if err != nil {
panic(err)
}
// Apply each patch individual against the original document
withoutCombinedPatch, err := jsonpatch.MergePatch(original, nameAndHeight)
if err != nil {
panic(err)
}
withoutCombinedPatch, err = jsonpatch.MergePatch(withoutCombinedPatch, ageAndEyes)
if err != nil {
panic(err)
}
// Apply the combined patch against the original document
withCombinedPatch, err := jsonpatch.MergePatch(original, combinedPatch)
if err != nil {
panic(err)
}
// Do both result in the same thing? They should!
if jsonpatch.Equal(withCombinedPatch, withoutCombinedPatch) {
fmt.Println("Both JSON documents are structurally the same!")
}
fmt.Printf("combined merge patch: %s", combinedPatch)
}
When ran, you get the following output:
$ go run main.go
Both JSON documents are structurally the same!
combined merge patch: {"age":4.23,"eyes":"blue","height":null,"name":"Jane"}
CLI for comparing JSON documents
You can install the commandline program json-patch.
This program can take multiple JSON patch documents as arguments,
and fed a JSON document from stdin. It will apply the patch(es) against
the document and output the modified doc.
patch.1.json
[
{"op": "replace", "path": "/name", "value": "Jane"},
{"op": "remove", "path": "/height"}
]
patch.2.json
[
{"op": "add", "path": "/address", "value": "123 Main St"},
{"op": "replace", "path": "/age", "value": "21"}
]
document.json
{
"name": "John",
"age": 24,
"height": 3.21
}
You can then run:
$ go install github.com/evanphx/json-patch/cmd/json-patch
$ cat document.json | json-patch -p patch.1.json -p patch.2.json
{"address":"123 Main St","age":"21","name":"Jane"}
Help It!
Contributions are welcomed! Leave an issue or create a PR.
Before creating a pull request, we'd ask that you make sure tests are passing and that you have added new tests when applicable.
Contributors can run tests using:
go test -cover ./...
Builds for pull requests are tested automatically using TravisCI.
Documentation
¶
Index ¶
Constants ¶
This section is empty.
Variables ¶
var SupportNegativeIndices bool = true
Functions ¶
func CreateMergePatch ¶
CreateMergePatch will return a merge patch document capable of converting the original document(s) to the modified document(s). The parameters can be bytes of either two JSON Documents, or two arrays of JSON documents. The merge patch returned follows the specification defined at http://tools.ietf.org/html/draft-ietf-appsawg-json-merge-patch-07
func MergeMergePatches ¶
MergeMergePatches merges two merge patches together, such that applying this resulting merged merge patch to a document yields the same as merging each merge patch to the document in succession.
func MergePatch ¶
MergePatch merges the patchData into the docData.
Source Files
Directories