cjson

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 Go to latest Published: Nov 2, 2026 License: Apache-2.0 Imports: 2 Imported by: 0

README

cJSON

GoDoc GitHub release LLGo LLGo bindings XGo

LLGo bindings for cJSON, enabling XGo/Go programs to parse, build and serialize JSON documents via the cJSON C API.

Installation

Install LLGo first, then install cJSON, its optional libcjson_utils library, and pkg-config for your platform. The binding links to both libraries through pkg-config.

These bindings are generated from cJSON 1.7.19, and the tests expect that exact library version. Package manager versions vary; if yours differs, use the source installation below to match the bindings.

macOS (Homebrew)
brew install cjson pkg-config
Linux

Ubuntu / Debian (libcjson-dev):

sudo apt update
sudo apt install libcjson-dev pkg-config

Fedora (cjson-devel):

sudo dnf install cjson-devel pkgconf-pkg-config

Arch Linux (cjson):

sudo pacman -S cjson pkgconf

Verify that your package provides both libcjson.pc and libcjson_utils.pc. Some older distribution packages build only the core library; use the source installation below with -DENABLE_CJSON_UTILS=ON in that case.

Windows

Set up the matching LLGo toolchain and pkg-config using the LLGo Windows guide, then install cJSON for the same architecture and ABI.

For MinGW, run the following in an MSYS2 CLANG64 shell (amd64):

pacman -S mingw-w64-clang-x86_64-cjson mingw-w64-clang-x86_64-pkgconf

For arm64, use a CLANGARM64 shell and replace mingw-w64-clang-x86_64- with mingw-w64-clang-aarch64-. See the MSYS2 cJSON packages. Keep the matching clang64/bin or clangarm64/bin directory on PATH when building and running programs so the cJSON DLL can be found.

For MSVC, install cJSON with your configured vcpkg (run from its directory in PowerShell):

.\vcpkg.exe install cjson:x64-windows pkgconf:x64-windows

Use arm64-windows instead of x64-windows for arm64. Configure pkg-config to use that triplet's metadata and add its bin directory to PATH, as described in the LLGo Windows guide. Keep MSVC and MinGW libraries in their respective toolchain environments.

If using WSL, follow the Linux instructions inside your WSL distribution and run Go and LLGo there.

From source (Linux / macOS, cJSON 1.7.19)

With Git, CMake, a C compiler, a build tool such as Make, and pkg-config installed, build the upstream v1.7.19 release:

git clone --depth 1 --branch v1.7.19 https://github.com/DaveGamble/cJSON.git cJSON-1.7.19
cmake -S cJSON-1.7.19 -B cJSON-1.7.19/build \
  -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
  -DCMAKE_BUILD_TYPE=Release \
  -DCMAKE_INSTALL_PREFIX="$HOME/.local" \
  -DCMAKE_INSTALL_LIBDIR=lib \
  -DBUILD_SHARED_LIBS=ON \
  -DENABLE_CJSON_UTILS=ON \
  -DENABLE_CJSON_TEST=OFF
cmake --build cJSON-1.7.19/build
cmake --install cJSON-1.7.19/build
export PKG_CONFIG_PATH="$HOME/.local/lib/pkgconfig${PKG_CONFIG_PATH:+:$PKG_CONFIG_PATH}"

On Linux, also make the shared library available at runtime:

export LD_LIBRARY_PATH="$HOME/.local/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}"

Keep these environment variables set in the terminal where you build and run your program, or add them to your shell profile.

Install the Go binding

Verify that pkg-config finds the intended cJSON installation:

pkg-config --modversion libcjson libcjson_utils
pkg-config --libs libcjson_utils

Then, from your Go module directory:

go get github.com/llarhub/cjson

The binding also exposes the JSON Pointer, JSON Patch, and JSON Merge Patch helpers from cJSON_Utils.h; these methods require libcjson_utils at link and runtime.

Usage

Parse JSON and read a string field:

package main

import (
	"github.com/goplus/lib/c"
	"github.com/llarhub/cjson"
)

func main() {
	root := cjson.Parse(c.Str(`{"name":"LLGo"}`))
	if root == nil {
		panic("invalid JSON")
	}
	defer root.Delete()

	name := root.ObjectItemCaseSensitive(c.Str("name"))
	if name != nil && name.IsString() != 0 {
		println(c.GoString(name.StringValue()))
	}
}

Save the example as main.go and run it with llgo run ..

Use the cJSON Utils API to resolve a JSON Pointer:

package main

import (
	"github.com/goplus/lib/c"
	"github.com/llarhub/cjson"
)

func main() {
	root := cjson.Parse(c.Str(`{"user":{"name":"LLGo"}}`))
	if root == nil {
		panic("invalid JSON")
	}
	defer root.Delete()

	name := root.Pointer(c.Str("/user/name"))
	if name == nil || name.IsString() == 0 {
		panic("JSON Pointer did not resolve to a string")
	}
	println(c.GoString(name.StringValue()))
}

This prints LLGo. The same package also provides JSON Patch and JSON Merge Patch helpers such as GeneratePatches, ApplyPatches, and MergePatch.

Documentation

Index

Constants

View Source 
const (
	VERSION_MAJOR = 1
	VERSION_MINOR = 7
	VERSION_PATCH = 19
)

project version

View Source 
const (
	Invalid = 0
	False   = 1
	True    = 2
	NULL    = 4
	Number  = 8
	String  = 16
	Array   = 32
	Object  = 64
	// raw json
	Raw = 128
)

cJSON Types:

View Source 
const (
	IsReference   = 256
	StringIsConst = 512
)
View Source 
const CIRCULAR_LIMIT = 10000
View Source 
const LLGoPackage = "link: $(pkg-config --libs libcjson_utils); -lcjson_utils -lcjson"
View Source 
const NESTING_LIMIT = 1000

Variables

This section is empty.

Functions

func FindPointerFromObjectTo added in v0.3.3 

func FindPointerFromObjectTo(object *Node, target *Node) *c.Char

Given a root object and a target object, construct a pointer from one to the other.

func Free 

func Free(object unsafe.Pointer)

func GetErrorPtr 

func GetErrorPtr() *c.Char

For analysing failed parses. This returns a pointer to the parse error. You'll probably need to look a few chars back to make sense of it. Defined when cJSON_Parse() returns 0. 0 when cJSON_Parse() succeeds.

func Malloc 

func Malloc(size c.SizeT) unsafe.Pointer

malloc/free objects using the malloc/free functions that have been set with cJSON_InitHooks

func Minify 

func Minify(json *c.Char)

Minify a strings, remove blank characters(such as ' ', '\t', '\r', '\n') from strings. The input pointer json cannot point to a read-only address area, such as a string constant, but should point to a readable and writable address area.

func Version 

func Version() *c.Char

returns the version of cJSON as a string

Types

type Bool 

type Bool = c.Int

func AddItemReferenceToArray added in v0.3.3 

func AddItemReferenceToArray(array *Node, item *Node) Bool

Append reference to item to the specified array/object. Use this when you want to add an existing cJSON to a new cJSON, but don't want to corrupt your existing cJSON.

func AddItemToArray added in v0.3.3 

func AddItemToArray(array *Node, item *Node) Bool

Append item to the specified array/object.

type Hooks 

type Hooks struct {
	MallocFn func(_llcppg_param1 c.SizeT) unsafe.Pointer
	FreeFn   func(_llcppg_param1 unsafe.Pointer)
}

func (*Hooks) Init 

func (self *Hooks) Init()

Supply malloc, realloc and free functions to cJSON

type Node added in v0.3.0 

type Node struct {
	Next        *Node
	Prev        *Node
	Child       *Node
	Type        c.Int
	Valuestring *c.Char
	Valueint    c.Int
	Valuedouble c.Double
	String      *c.Char
}

The cJSON structure:

func CreateArray 

func CreateArray() *Node

func CreateBool 

func CreateBool(boolean Bool) *Node

func CreateDoubleArray 

func CreateDoubleArray(numbers *c.Double, count c.Int) *Node

func CreateFalse 

func CreateFalse() *Node

func CreateFloatArray 

func CreateFloatArray(numbers *c.Float, count c.Int) *Node

func CreateIntArray 

func CreateIntArray(numbers *c.Int, count c.Int) *Node

These utilities create an Array of count items. The parameter count cannot be greater than the number of elements in the number array, otherwise array access will be out of bounds.

func CreateNull 

func CreateNull() *Node

These calls create a cJSON item of the appropriate type.

func CreateNumber 

func CreateNumber(num c.Double) *Node

func CreateObject 

func CreateObject() *Node

func CreateRaw 

func CreateRaw(raw *c.Char) *Node

raw json

func CreateString 

func CreateString(string *c.Char) *Node

raw json

func CreateStringArray 

func CreateStringArray(strings **c.Char, count c.Int) *Node

func CreateStringReference 

func CreateStringReference(string *c.Char) *Node

Create a string where valuestring references a string so it will not be freed by cJSON_Delete

func CreateTrue 

func CreateTrue() *Node

func DetachItemViaPointer added in v0.3.3 

func DetachItemViaPointer(parent *Node, item *Node) *Node

Remove/Detach items from Arrays/Objects.

func GenerateMergePatch added in v0.3.3 

func GenerateMergePatch(from *Node, to *Node) *Node

NOTE: This modifies objects in 'from' and 'to' by sorting the elements by their key

func GenerateMergePatchCaseSensitive added in v0.3.3 

func GenerateMergePatchCaseSensitive(from *Node, to *Node) *Node

func GeneratePatches added in v0.3.3 

func GeneratePatches(from *Node, to *Node) *Node

NOTE: This modifies objects in 'from' and 'to' by sorting the elements by their key

func GeneratePatchesCaseSensitive added in v0.3.3 

func GeneratePatchesCaseSensitive(from *Node, to *Node) *Node

Utility for generating patch array entries.

func Parse 

func Parse(value *c.Char) *Node

Supply a block of JSON, and this returns a cJSON object you can interrogate.

func ParseWithLength 

func ParseWithLength(value *c.Char, buffer_length c.SizeT) *Node

ParseWithOpts allows you to require (and check) that the JSON is null terminated, and to retrieve the pointer to the final byte parsed.

func ParseWithLengthOpts 

func ParseWithLengthOpts(value *c.Char, buffer_length c.SizeT, return_parse_end **c.Char, require_null_terminated Bool) *Node

func ParseWithOpts 

func ParseWithOpts(value *c.Char, return_parse_end **c.Char, require_null_terminated Bool) *Node

If you supply a ptr in return_parse_end and parsing fails, then return_parse_end will contain a pointer to the error so will match cJSON_GetErrorPtr().

func (*Node) AddArrayToObject added in v0.3.0 

func (self *Node) AddArrayToObject(name *c.Char) *Node

func (*Node) AddBoolToObject added in v0.3.0 

func (self *Node) AddBoolToObject(name *c.Char, boolean Bool) *Node

func (*Node) AddFalseToObject added in v0.3.0 

func (self *Node) AddFalseToObject(name *c.Char) *Node

func (*Node) AddItemReferenceToObject added in v0.3.0 

func (self *Node) AddItemReferenceToObject(string *c.Char, item *Node) Bool

func (*Node) AddItemToObject added in v0.3.0 

func (self *Node) AddItemToObject(string *c.Char, item *Node) Bool

Use this when string is definitely const (i.e. a literal, or as good as), and will definitely survive the cJSON object. WARNING: When this function was used, make sure to always check that (item->type & cJSON_StringIsConst) is zero before writing to `item->string`

func (*Node) AddItemToObjectCS added in v0.3.0 

func (self *Node) AddItemToObjectCS(string *c.Char, item *Node) Bool

Use this when string is definitely const (i.e. a literal, or as good as), and will definitely survive the cJSON object. WARNING: When this function was used, make sure to always check that (item->type & cJSON_StringIsConst) is zero before writing to `item->string`

func (*Node) AddNullToObject added in v0.3.0 

func (self *Node) AddNullToObject(name *c.Char) *Node

Helper functions for creating and adding items to an object at the same time. They return the added item or NULL on failure.

func (*Node) AddNumberToObject added in v0.3.0 

func (self *Node) AddNumberToObject(name *c.Char, number c.Double) *Node

func (*Node) AddObjectToObject added in v0.3.0 

func (self *Node) AddObjectToObject(name *c.Char) *Node

func (*Node) AddPatchToArray added in v0.3.0 

func (self *Node) AddPatchToArray(operation *c.Char, path *c.Char, value *Node)

Utility for generating patch array entries.

func (*Node) AddRawToObject added in v0.3.0 

func (self *Node) AddRawToObject(name *c.Char, raw *c.Char) *Node

func (*Node) AddStringToObject added in v0.3.0 

func (self *Node) AddStringToObject(name *c.Char, string *c.Char) *Node

func (*Node) AddTrueToObject added in v0.3.0 

func (self *Node) AddTrueToObject(name *c.Char) *Node

func (*Node) ApplyPatches added in v0.3.0 

func (self *Node) ApplyPatches(patches *Node) c.Int

Returns 0 for success.

func (*Node) ApplyPatchesCaseSensitive added in v0.3.0 

func (self *Node) ApplyPatchesCaseSensitive(patches *Node) c.Int

func (*Node) ArrayItem added in v0.3.0 

func (self *Node) ArrayItem(index c.Int) *Node

Retrieve item number "index" from array "array". Returns NULL if unsuccessful.

func (*Node) ArraySize added in v0.3.0 

func (self *Node) ArraySize() c.Int

Returns the number of items in an array (or object).

func (*Node) Compare added in v0.3.0 

func (self *Node) Compare(b *Node, case_sensitive Bool) Bool

Recursively compare two cJSON items for equality. If either a or b is NULL or invalid, they will be considered unequal. case_sensitive determines if object keys are treated case sensitive (1) or case insensitive (0)

func (*Node) CreateArrayReference added in v0.3.0 

func (self *Node) CreateArrayReference() *Node

func (*Node) CreateObjectReference added in v0.3.0 

func (self *Node) CreateObjectReference() *Node

Create an object/array that only references it's elements so they will not be freed by cJSON_Delete

func (*Node) Delete added in v0.3.0 

func (self *Node) Delete()

Delete a cJSON entity and all subentities.

func (*Node) DeleteItemFromArray added in v0.3.0 

func (self *Node) DeleteItemFromArray(which c.Int)

func (*Node) DeleteItemFromObject added in v0.3.0 

func (self *Node) DeleteItemFromObject(string *c.Char)

func (*Node) DeleteItemFromObjectCaseSensitive added in v0.3.0 

func (self *Node) DeleteItemFromObjectCaseSensitive(string *c.Char)

func (*Node) DetachItemFromArray added in v0.3.0 

func (self *Node) DetachItemFromArray(which c.Int) *Node

func (*Node) DetachItemFromObject added in v0.3.0 

func (self *Node) DetachItemFromObject(string *c.Char) *Node

func (*Node) DetachItemFromObjectCaseSensitive added in v0.3.0 

func (self *Node) DetachItemFromObjectCaseSensitive(string *c.Char) *Node

func (*Node) Duplicate added in v0.3.0 

func (self *Node) Duplicate(recurse Bool) *Node

Duplicate a cJSON item

func (*Node) HasObjectItem added in v0.3.0 

func (self *Node) HasObjectItem(string *c.Char) Bool

For analysing failed parses. This returns a pointer to the parse error. You'll probably need to look a few chars back to make sense of it. Defined when cJSON_Parse() returns 0. 0 when cJSON_Parse() succeeds.

func (*Node) InsertItemInArray added in v0.3.0 

func (self *Node) InsertItemInArray(which c.Int, newitem *Node) Bool

Update array items.

func (*Node) IsArray added in v0.3.0 

func (self *Node) IsArray() Bool

func (*Node) IsBool added in v0.3.0 

func (self *Node) IsBool() Bool

func (*Node) IsFalse added in v0.3.0 

func (self *Node) IsFalse() Bool

func (*Node) IsInvalid added in v0.3.0 

func (self *Node) IsInvalid() Bool

These functions check the type of an item

func (*Node) IsNull added in v0.3.0 

func (self *Node) IsNull() Bool

func (*Node) IsNumber added in v0.3.0 

func (self *Node) IsNumber() Bool

func (*Node) IsObject added in v0.3.0 

func (self *Node) IsObject() Bool

func (*Node) IsRaw added in v0.3.0 

func (self *Node) IsRaw() Bool

func (*Node) IsString added in v0.3.0 

func (self *Node) IsString() Bool

func (*Node) IsTrue added in v0.3.0 

func (self *Node) IsTrue() Bool

func (*Node) MergePatch added in v0.3.0 

func (self *Node) MergePatch(patch *Node) *Node

target will be modified by patch. return value is new ptr for target.

func (*Node) MergePatchCaseSensitive added in v0.3.0 

func (self *Node) MergePatchCaseSensitive(patch *Node) *Node

generates a patch to move from -> to

func (*Node) NumberValue added in v0.3.0 

func (self *Node) NumberValue() c.Double

func (*Node) ObjectItem added in v0.3.0 

func (self *Node) ObjectItem(string *c.Char) *Node

Get item "string" from object. Case insensitive.

func (*Node) ObjectItemCaseSensitive added in v0.3.0 

func (self *Node) ObjectItemCaseSensitive(string *c.Char) *Node

func (*Node) Pointer added in v0.3.0 

func (self *Node) Pointer(pointer *c.Char) *Node

Implement RFC6901 (https://tools.ietf.org/html/rfc6901) JSON Pointer spec.

func (*Node) PointerCaseSensitive added in v0.3.0 

func (self *Node) PointerCaseSensitive(pointer *c.Char) *Node

func (*Node) Print added in v0.3.0 

func (self *Node) Print() *c.Char

Render a cJSON entity to text for transfer/storage.

func (*Node) PrintBuffered added in v0.3.0 

func (self *Node) PrintBuffered(prebuffer c.Int, fmt Bool) *c.Char

Render a cJSON entity to text using a buffered strategy. prebuffer is a guess at the final size. guessing well reduces reallocation. fmt=0 gives unformatted, =1 gives formatted

func (*Node) PrintPreallocated added in v0.3.0 

func (self *Node) PrintPreallocated(buffer *c.Char, length c.Int, format Bool) Bool

NOTE: cJSON is not always 100% accurate in estimating how much memory it will use, so to be safe allocate 5 bytes more than you actually need

func (*Node) PrintUnformatted added in v0.3.0 

func (self *Node) PrintUnformatted() *c.Char

Render a cJSON entity to text for transfer/storage without any formatting.

func (*Node) ReplaceItemInArray added in v0.3.0 

func (self *Node) ReplaceItemInArray(which c.Int, newitem *Node) Bool

func (*Node) ReplaceItemInObject added in v0.3.0 

func (self *Node) ReplaceItemInObject(string *c.Char, newitem *Node) Bool

func (*Node) ReplaceItemInObjectCaseSensitive added in v0.3.0 

func (self *Node) ReplaceItemInObjectCaseSensitive(string *c.Char, newitem *Node) Bool

func (*Node) ReplaceItemViaPointer added in v0.3.0 

func (self *Node) ReplaceItemViaPointer(item *Node, replacement *Node) Bool

func (*Node) SetNumberHelper added in v0.3.0 

func (self *Node) SetNumberHelper(number c.Double) c.Double

helper for the cJSON_SetNumberValue macro

func (*Node) SetValuestring added in v0.3.0 

func (self *Node) SetValuestring(valuestring *c.Char) *c.Char

Change the valuestring of a cJSON_String object, only takes effect when type of object is cJSON_String

func (*Node) SortObject added in v0.3.0 

func (self *Node) SortObject()

Sorts the members of the object into alphabetical order.

func (*Node) SortObjectCaseSensitive added in v0.3.0 

func (self *Node) SortObjectCaseSensitive()

func (*Node) StringValue added in v0.3.0 

func (self *Node) StringValue() *c.Char

Check item type and return its value

Source Files

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