ldclabs / cbor-patch

A Go library to apply RFC6902 patches on CBOR

CBOR-Patch

cborpatch is a library which provides functionality for applying RFC6902 JSON patches on CBOR.å

cborpatch supports positive integer, negative integer, byte string and UTF-8 text string as map key.

Import

// package cborpatch
import "github.com/ldclabs/cbor-patch"

Examples

Create and apply a CBOR Patch

package main

import (
	"fmt"

	cborpatch "github.com/ldclabs/cbor-patch"
)

func main() {
	original := cborpatch.MustFromJSON(`{"name": "John", "age": 24, "height": 3.21}`)
	fmt.Printf("%x\n", original)
	// a3636167651818646e616d65644a6f686e66686569676874fb4009ae147ae147ae

	patch, err := cborpatch.PatchFromJSON(`[
		{"op": "replace", "path": "/name", "value": "Jane"},
		{"op": "remove", "path": "/height"}
	]`)
	if err != nil {
		panic(err)
	}
	modified, err := patch.Apply(original)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%x\n", modified)
	// a2636167651818646e616d65644a616e65
	fmt.Printf("%s\n", cborpatch.MustToJSON(modified))
	// {"age":24,"name":"Jane"}
}

Create a Node and apply more Patchs

package main

import (
	"fmt"

	cborpatch "github.com/ldclabs/cbor-patch"
)

func main() {
	original := cborpatch.MustFromJSON(`{"name": "John", "age": 24, "height": 3.21}`)
	fmt.Printf("%x\n", original)
	// a3636167651818646e616d65644a6f686e66686569676874fb4009ae147ae147ae

	node := cborpatch.NewNode(original)
	patch, err := cborpatch.PatchFromJSON(`[
		{"op": "replace", "path": "/name", "value": "Jane"},
		{"op": "remove", "path": "/height"}
	]`)
	if err != nil {
		panic(err)
	}
	err = node.Patch(patch, nil)
	if err != nil {
		panic(err)
	}
	modified, err := node.MarshalCBOR()
	if err != nil {
		panic(err)
	}
	fmt.Printf("%x\n", modified)
	// a2636167651818646e616d65644a616e65
	modified, err = node.MarshalJSON()
	if err != nil {
		panic(err)
	}
	fmt.Printf("%s\n", string(modified))
	// {"age":24,"name":"Jane"}

	patch, err = cborpatch.PatchFromJSON(`[
		{"op": "replace", "path": "/age", "value": 25}
	]`)
	if err != nil {
		panic(err)
	}
	err = node.Patch(patch, nil)
	if err != nil {
		panic(err)
	}
	modified, err = node.MarshalCBOR()
	if err != nil {
		panic(err)
	}
	fmt.Printf("%x\n", modified)
	// a2636167651819646e616d65644a616e65
	modified, err = node.MarshalJSON()
	if err != nil {
		panic(err)
	}
	fmt.Printf("%s\n", string(modified))
	// {"age":25,"name":"Jane"}
}

Get value by path

package main

import (
	"fmt"

	cborpatch "github.com/ldclabs/cbor-patch"
)

func main() {
	doc := cborpatch.MustFromJSON(`{
		"baz": "qux",
		"foo": [ "a", 2, "c" ]
	}`)
	node := cborpatch.NewNode(doc)
	path, err := cborpatch.PathFromJSON("/foo/0")
	if err != nil {
		panic(err)
	}

	value, err := node.GetValue(path, nil)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%x\n", value)
	// 6161
	fmt.Printf("%s\n", cborpatch.MustToJSON(value))
	// "a"
}

Find children by test operations

package main

import (
	"fmt"

	cborpatch "github.com/ldclabs/cbor-patch"
)

func main() {
	doc := cborpatch.MustFromJSON(`["root", ["p",
		["span", {"data-type": "text"},
			["span", {"data-type": "leaf"}, "Hello 1"],
			["span", {"data-type": "leaf"}, "Hello 2"],
			["span", {"data-type": "leaf"}, "Hello 3"],
			["span", {"data-type": null}, "Hello 4"]
		]
	]]`)

	node := cborpatch.NewNode(doc)
	tests := cborpatch.PVs{
		{cborpatch.PathMustFromJSON("/0"), cborpatch.MustFromJSON(`"span"`)},
		{cborpatch.PathMustFromJSON("/1/data-type"), cborpatch.MustFromJSON(`"leaf"`)},
	}

	result, err := node.FindChildren(tests, nil)
	if err != nil {
		panic(err)
	}
	for _, r := range result {
		fmt.Printf("Path: %s, Value: %x, JSON: %s\n", r.Path, r.Value, cborpatch.MustToJSON(r.Value))
	}

	// Output:
	// Path: [1, 1, 2], Value: 83647370616ea169646174612d74797065646c6561666748656c6c6f2031, JSON: ["span",{"data-type":"leaf"},"Hello 1"]
	// Path: [1, 1, 3], Value: 83647370616ea169646174612d74797065646c6561666748656c6c6f2032, JSON: ["span",{"data-type":"leaf"},"Hello 2"]
	// Path: [1, 1, 4], Value: 83647370616ea169646174612d74797065646c6561666748656c6c6f2033, JSON: ["span",{"data-type":"leaf"},"Hello 3"]
}