Files
dualfroz 5b70965fcb fix: allow setting and deleting an empty object key
An empty string is a valid JSON object key and gjson reads it, but set()
rejected an empty path outright, so such a key could neither be changed
nor removed through sjson.

Nothing below that guard needed a non-empty path. parsePath("") already
returns a well-formed simple pathResult and gjson.Get resolves the empty
key. What did break was atoui: its digit loop never runs for an empty
part, so it fell through and reported the empty key as numeric index 0.

That also affected paths the guard never blocked. A nested empty key was
built as an array, so Set(`{"x":1}`, "a.", 2) produced
{"x":1,"a":[2]}, which gjson cannot read back.

Return false from atoui for an empty part and drop the guard. An empty
key on an array now reports the same error as any other non-numeric key
instead of a special-cased one.

Fixes #77
2026-09-03 14:27:28 +02:00

749 lines
19 KiB
Go

// Package sjson provides setting json values.
package sjson
import (
jsongo "encoding/json"
"sort"
"strconv"
"unsafe"
"github.com/tidwall/gjson"
)
type errorType struct {
msg string
}
func (err *errorType) Error() string {
return err.msg
}
// Options represents additional options for the Set and Delete functions.
type Options struct {
// Optimistic is a hint that the value likely exists which
// allows for the sjson to perform a fast-track search and replace.
Optimistic bool
// ReplaceInPlace is a hint to replace the input json rather than
// allocate a new json byte slice. When this field is specified
// the input json will not longer be valid and it should not be used
// In the case when the destination slice doesn't have enough free
// bytes to replace the data in place, a new bytes slice will be
// created under the hood.
// The Optimistic flag must be set to true and the input must be a
// byte slice in order to use this field.
ReplaceInPlace bool
}
type pathResult struct {
part string // current key part
gpart string // gjson get part
path string // remaining path
force bool // force a string key
more bool // there is more path to parse
}
func isSimpleChar(ch byte) bool {
switch ch {
case '|', '#', '@', '*', '?':
return false
default:
return true
}
}
func parsePath(path string) (res pathResult, simple bool) {
var r pathResult
if len(path) > 0 && path[0] == ':' {
r.force = true
path = path[1:]
}
for i := 0; i < len(path); i++ {
if path[i] == '.' {
r.part = path[:i]
r.gpart = path[:i]
r.path = path[i+1:]
r.more = true
return r, true
}
if !isSimpleChar(path[i]) {
return r, false
}
if path[i] == '\\' {
// go into escape mode. this is a slower path that
// strips off the escape character from the part.
epart := []byte(path[:i])
gpart := []byte(path[:i+1])
i++
if i < len(path) {
epart = append(epart, path[i])
gpart = append(gpart, path[i])
i++
for ; i < len(path); i++ {
if path[i] == '\\' {
gpart = append(gpart, '\\')
i++
if i < len(path) {
epart = append(epart, path[i])
gpart = append(gpart, path[i])
}
continue
} else if path[i] == '.' {
r.part = string(epart)
r.gpart = string(gpart)
r.path = path[i+1:]
r.more = true
return r, true
} else if !isSimpleChar(path[i]) {
return r, false
}
epart = append(epart, path[i])
gpart = append(gpart, path[i])
}
}
// append the last part
r.part = string(epart)
r.gpart = string(gpart)
return r, true
}
}
r.part = path
r.gpart = path
return r, true
}
func mustMarshalString(s string) bool {
for i := 0; i < len(s); i++ {
if s[i] < ' ' || s[i] > 0x7f || s[i] == '"' || s[i] == '\\' {
return true
}
}
return false
}
// appendStringify makes a json string and appends to buf.
func appendStringify(buf []byte, s string) []byte {
if mustMarshalString(s) {
b, _ := jsongo.Marshal(s)
return append(buf, b...)
}
buf = append(buf, '"')
buf = append(buf, s...)
buf = append(buf, '"')
return buf
}
// appendBuild builds a json block from a json path.
func appendBuild(buf []byte, array bool, paths []pathResult, raw string,
stringify bool) []byte {
if !array {
buf = appendStringify(buf, paths[0].part)
buf = append(buf, ':')
}
if len(paths) > 1 {
n, numeric := atoui(paths[1])
if numeric || (!paths[1].force && paths[1].part == "-1") {
buf = append(buf, '[')
buf = appendRepeat(buf, "null,", n)
buf = appendBuild(buf, true, paths[1:], raw, stringify)
buf = append(buf, ']')
} else {
buf = append(buf, '{')
buf = appendBuild(buf, false, paths[1:], raw, stringify)
buf = append(buf, '}')
}
} else {
if stringify {
buf = appendStringify(buf, raw)
} else {
buf = append(buf, raw...)
}
}
return buf
}
// atoui does a rip conversion of string -> unigned int.
func atoui(r pathResult) (n int, ok bool) {
if r.force {
return 0, false
}
if len(r.part) == 0 {
// An empty key is a valid object key, not the number zero.
return 0, false
}
for i := 0; i < len(r.part); i++ {
if r.part[i] < '0' || r.part[i] > '9' {
return 0, false
}
n = n*10 + int(r.part[i]-'0')
}
return n, true
}
// appendRepeat repeats string "n" times and appends to buf.
func appendRepeat(buf []byte, s string, n int) []byte {
for i := 0; i < n; i++ {
buf = append(buf, s...)
}
return buf
}
// trim does a rip trim
func trim(s string) string {
for len(s) > 0 {
if s[0] <= ' ' {
s = s[1:]
continue
}
break
}
for len(s) > 0 {
if s[len(s)-1] <= ' ' {
s = s[:len(s)-1]
continue
}
break
}
return s
}
// deleteTailItem deletes the previous key or comma.
func deleteTailItem(buf []byte) ([]byte, bool) {
loop:
for i := len(buf) - 1; i >= 0; i-- {
// look for either a ',',':','['
switch buf[i] {
case '[':
return buf, true
case ',':
return buf[:i], false
case ':':
// delete tail string
i--
for ; i >= 0; i-- {
if buf[i] == '"' {
i--
for ; i >= 0; i-- {
if buf[i] == '"' {
i--
if i >= 0 && buf[i] == '\\' {
i--
continue
}
for ; i >= 0; i-- {
// look for either a ',','{'
switch buf[i] {
case '{':
return buf[:i+1], true
case ',':
return buf[:i], false
}
}
}
}
break
}
}
break loop
}
}
return buf, false
}
var errNoChange = &errorType{"no change"}
func appendRawPaths(buf []byte, jstr string, paths []pathResult, raw string,
stringify, del bool) ([]byte, error) {
var err error
var res gjson.Result
var found bool
if del {
if paths[0].part == "-1" && !paths[0].force {
res = gjson.Get(jstr, "#")
if res.Int() > 0 {
res = gjson.Get(jstr, strconv.FormatInt(int64(res.Int()-1), 10))
found = true
}
}
}
if !found {
res = gjson.Get(jstr, paths[0].gpart)
}
if res.Index > 0 {
if len(paths) > 1 {
buf = append(buf, jstr[:res.Index]...)
buf, err = appendRawPaths(buf, res.Raw, paths[1:], raw,
stringify, del)
if err != nil {
return nil, err
}
buf = append(buf, jstr[res.Index+len(res.Raw):]...)
return buf, nil
}
buf = append(buf, jstr[:res.Index]...)
var exidx int // additional forward stripping
if del {
var delNextComma bool
buf, delNextComma = deleteTailItem(buf)
if delNextComma {
i, j := res.Index+len(res.Raw), 0
for ; i < len(jstr); i, j = i+1, j+1 {
if jstr[i] <= ' ' {
continue
}
if jstr[i] == ',' {
exidx = j + 1
}
break
}
}
} else {
if stringify {
buf = appendStringify(buf, raw)
} else {
buf = append(buf, raw...)
}
}
buf = append(buf, jstr[res.Index+len(res.Raw)+exidx:]...)
return buf, nil
}
if del {
return nil, errNoChange
}
n, numeric := atoui(paths[0])
isempty := true
for i := 0; i < len(jstr); i++ {
if jstr[i] > ' ' {
isempty = false
break
}
}
if isempty {
if numeric {
jstr = "[]"
} else {
jstr = "{}"
}
}
jsres := gjson.Parse(jstr)
if jsres.Type != gjson.JSON {
if numeric {
jstr = "[]"
} else {
jstr = "{}"
}
jsres = gjson.Parse(jstr)
}
var comma bool
for i := 1; i < len(jsres.Raw); i++ {
if jsres.Raw[i] <= ' ' {
continue
}
if jsres.Raw[i] == '}' || jsres.Raw[i] == ']' {
break
}
comma = true
break
}
switch jsres.Raw[0] {
default:
return nil, &errorType{"json must be an object or array"}
case '{':
end := len(jsres.Raw) - 1
for ; end > 0; end-- {
if jsres.Raw[end] == '}' {
break
}
}
buf = append(buf, jsres.Raw[:end]...)
if comma {
buf = append(buf, ',')
}
buf = appendBuild(buf, false, paths, raw, stringify)
buf = append(buf, '}')
return buf, nil
case '[':
var appendit bool
if !numeric {
if paths[0].part == "-1" && !paths[0].force {
appendit = true
} else {
return nil, &errorType{
"cannot set array element for non-numeric key '" +
paths[0].part + "'"}
}
}
if appendit {
njson := trim(jsres.Raw)
if njson[len(njson)-1] == ']' {
njson = njson[:len(njson)-1]
}
buf = append(buf, njson...)
if comma {
buf = append(buf, ',')
}
buf = appendBuild(buf, true, paths, raw, stringify)
buf = append(buf, ']')
return buf, nil
}
buf = append(buf, '[')
ress := jsres.Array()
for i := 0; i < len(ress); i++ {
if i > 0 {
buf = append(buf, ',')
}
buf = append(buf, ress[i].Raw...)
}
if len(ress) == 0 {
buf = appendRepeat(buf, "null,", n-len(ress))
} else {
buf = appendRepeat(buf, ",null", n-len(ress))
if comma {
buf = append(buf, ',')
}
}
buf = appendBuild(buf, true, paths, raw, stringify)
buf = append(buf, ']')
return buf, nil
}
}
func isOptimisticPath(path string) bool {
for i := 0; i < len(path); i++ {
if path[i] < '.' || path[i] > 'z' {
return false
}
if path[i] > '9' && path[i] < 'A' {
return false
}
if path[i] > 'z' {
return false
}
}
return true
}
// Set sets a json value for the specified path.
// A path is in dot syntax, such as "name.last" or "age".
// This function expects that the json is well-formed, and does not validate.
// Invalid json will not panic, but it may return back unexpected results.
// An error is returned if the path is not valid.
//
// A path is a series of keys separated by a dot.
//
// {
// "name": {"first": "Tom", "last": "Anderson"},
// "age":37,
// "children": ["Sara","Alex","Jack"],
// "friends": [
// {"first": "James", "last": "Murphy"},
// {"first": "Roger", "last": "Craig"}
// ]
// }
// "name.last" >> "Anderson"
// "age" >> 37
// "children.1" >> "Alex"
//
func Set(json, path string, value interface{}) (string, error) {
return SetOptions(json, path, value, nil)
}
// SetBytes sets a json value for the specified path.
// If working with bytes, this method preferred over
// Set(string(data), path, value)
func SetBytes(json []byte, path string, value interface{}) ([]byte, error) {
return SetBytesOptions(json, path, value, nil)
}
// SetRaw sets a raw json value for the specified path.
// This function works the same as Set except that the value is set as a
// raw block of json. This allows for setting premarshalled json objects.
func SetRaw(json, path, value string) (string, error) {
return SetRawOptions(json, path, value, nil)
}
// SetRawOptions sets a raw json value for the specified path with options.
// This furnction works the same as SetOptions except that the value is set
// as a raw block of json. This allows for setting premarshalled json objects.
func SetRawOptions(json, path, value string, opts *Options) (string, error) {
var optimistic bool
if opts != nil {
optimistic = opts.Optimistic
}
res, err := set(json, path, value, false, false, optimistic, false)
if err == errNoChange {
return json, nil
}
return string(res), err
}
// SetRawBytes sets a raw json value for the specified path.
// If working with bytes, this method preferred over
// SetRaw(string(data), path, value)
func SetRawBytes(json []byte, path string, value []byte) ([]byte, error) {
return SetRawBytesOptions(json, path, value, nil)
}
type dtype struct{}
// Delete deletes a value from json for the specified path.
func Delete(json, path string) (string, error) {
return Set(json, path, dtype{})
}
// DeleteOptions deletes a value from json for the specified path, with the given options.
func DeleteOptions(json, path string, options *Options) (string, error) {
return SetOptions(json, path, dtype{}, options)
}
// DeleteBytes deletes a value from json for the specified path.
func DeleteBytes(json []byte, path string) ([]byte, error) {
return SetBytes(json, path, dtype{})
}
// DeleteBytesOptions deletes a value from json for the specified path, with the given options.
func DeleteBytesOptions(json []byte, path string, options *Options) ([]byte, error) {
return SetBytesOptions(json, path, dtype{}, options)
}
type stringHeader struct {
data unsafe.Pointer
len int
}
type sliceHeader struct {
data unsafe.Pointer
len int
cap int
}
func set(jstr, path, raw string,
stringify, del, optimistic, inplace bool) ([]byte, error) {
if !del && optimistic && isOptimisticPath(path) {
res := gjson.Get(jstr, path)
if res.Exists() && res.Index > 0 {
sz := len(jstr) - len(res.Raw) + len(raw)
if stringify {
sz += 2
}
if inplace && sz <= len(jstr) {
if !stringify || !mustMarshalString(raw) {
jsonh := *(*stringHeader)(unsafe.Pointer(&jstr))
jsonbh := sliceHeader{
data: jsonh.data, len: jsonh.len, cap: jsonh.len}
jbytes := *(*[]byte)(unsafe.Pointer(&jsonbh))
if stringify {
jbytes[res.Index] = '"'
copy(jbytes[res.Index+1:], []byte(raw))
jbytes[res.Index+1+len(raw)] = '"'
copy(jbytes[res.Index+1+len(raw)+1:],
jbytes[res.Index+len(res.Raw):])
} else {
copy(jbytes[res.Index:], []byte(raw))
copy(jbytes[res.Index+len(raw):],
jbytes[res.Index+len(res.Raw):])
}
return jbytes[:sz], nil
}
return []byte(jstr), nil
}
buf := make([]byte, 0, sz)
buf = append(buf, jstr[:res.Index]...)
if stringify {
buf = appendStringify(buf, raw)
} else {
buf = append(buf, raw...)
}
buf = append(buf, jstr[res.Index+len(res.Raw):]...)
return buf, nil
}
}
var paths []pathResult
r, simple := parsePath(path)
if simple {
paths = append(paths, r)
for r.more {
r, simple = parsePath(r.path)
if !simple {
break
}
paths = append(paths, r)
}
}
if !simple {
if del {
return []byte(jstr),
&errorType{"cannot delete value from a complex path"}
}
return setComplexPath(jstr, path, raw, stringify)
}
njson, err := appendRawPaths(nil, jstr, paths, raw, stringify, del)
if err != nil {
return []byte(jstr), err
}
return njson, nil
}
func setComplexPath(jstr, path, raw string, stringify bool) ([]byte, error) {
res := gjson.Get(jstr, path)
if !res.Exists() || !(res.Index != 0 || len(res.Indexes) != 0) {
return []byte(jstr), errNoChange
}
if res.Index != 0 {
njson := []byte(jstr[:res.Index])
if stringify {
njson = appendStringify(njson, raw)
} else {
njson = append(njson, raw...)
}
njson = append(njson, jstr[res.Index+len(res.Raw):]...)
jstr = string(njson)
}
if len(res.Indexes) > 0 {
type val struct {
index int
res gjson.Result
}
vals := make([]val, 0, len(res.Indexes))
res.ForEach(func(_, vres gjson.Result) bool {
vals = append(vals, val{res: vres})
return true
})
if len(res.Indexes) != len(vals) {
return []byte(jstr), errNoChange
}
for i := 0; i < len(res.Indexes); i++ {
vals[i].index = res.Indexes[i]
}
sort.SliceStable(vals, func(i, j int) bool {
return vals[i].index > vals[j].index
})
for _, val := range vals {
vres := val.res
index := val.index
njson := []byte(jstr[:index])
if stringify {
njson = appendStringify(njson, raw)
} else {
njson = append(njson, raw...)
}
njson = append(njson, jstr[index+len(vres.Raw):]...)
jstr = string(njson)
}
}
return []byte(jstr), nil
}
// SetOptions sets a json value for the specified path with options.
// A path is in dot syntax, such as "name.last" or "age".
// This function expects that the json is well-formed, and does not validate.
// Invalid json will not panic, but it may return back unexpected results.
// An error is returned if the path is not valid.
func SetOptions(json, path string, value interface{},
opts *Options) (string, error) {
if opts != nil {
if opts.ReplaceInPlace {
// it's not safe to replace bytes in-place for strings
// copy the Options and set options.ReplaceInPlace to false.
nopts := *opts
opts = &nopts
opts.ReplaceInPlace = false
}
}
jsonh := *(*stringHeader)(unsafe.Pointer(&json))
jsonbh := sliceHeader{data: jsonh.data, len: jsonh.len, cap: jsonh.len}
jsonb := *(*[]byte)(unsafe.Pointer(&jsonbh))
res, err := SetBytesOptions(jsonb, path, value, opts)
return string(res), err
}
// SetBytesOptions sets a json value for the specified path with options.
// If working with bytes, this method preferred over
// SetOptions(string(data), path, value)
func SetBytesOptions(json []byte, path string, value interface{},
opts *Options) ([]byte, error) {
var optimistic, inplace bool
if opts != nil {
optimistic = opts.Optimistic
inplace = opts.ReplaceInPlace
}
jstr := *(*string)(unsafe.Pointer(&json))
var res []byte
var err error
switch v := value.(type) {
default:
b, merr := jsongo.Marshal(value)
if merr != nil {
return nil, merr
}
raw := *(*string)(unsafe.Pointer(&b))
res, err = set(jstr, path, raw, false, false, optimistic, inplace)
case dtype:
res, err = set(jstr, path, "", false, true, optimistic, inplace)
case string:
res, err = set(jstr, path, v, true, false, optimistic, inplace)
case []byte:
raw := *(*string)(unsafe.Pointer(&v))
res, err = set(jstr, path, raw, true, false, optimistic, inplace)
case bool:
if v {
res, err = set(jstr, path, "true", false, false, optimistic, inplace)
} else {
res, err = set(jstr, path, "false", false, false, optimistic, inplace)
}
case int8:
res, err = set(jstr, path, strconv.FormatInt(int64(v), 10),
false, false, optimistic, inplace)
case int16:
res, err = set(jstr, path, strconv.FormatInt(int64(v), 10),
false, false, optimistic, inplace)
case int32:
res, err = set(jstr, path, strconv.FormatInt(int64(v), 10),
false, false, optimistic, inplace)
case int64:
res, err = set(jstr, path, strconv.FormatInt(int64(v), 10),
false, false, optimistic, inplace)
case uint8:
res, err = set(jstr, path, strconv.FormatUint(uint64(v), 10),
false, false, optimistic, inplace)
case uint16:
res, err = set(jstr, path, strconv.FormatUint(uint64(v), 10),
false, false, optimistic, inplace)
case uint32:
res, err = set(jstr, path, strconv.FormatUint(uint64(v), 10),
false, false, optimistic, inplace)
case uint64:
res, err = set(jstr, path, strconv.FormatUint(uint64(v), 10),
false, false, optimistic, inplace)
case float32:
res, err = set(jstr, path, strconv.FormatFloat(float64(v), 'f', -1, 64),
false, false, optimistic, inplace)
case float64:
res, err = set(jstr, path, strconv.FormatFloat(float64(v), 'f', -1, 64),
false, false, optimistic, inplace)
}
if err == errNoChange {
return json, nil
}
return res, err
}
// SetRawBytesOptions sets a raw json value for the specified path with options.
// If working with bytes, this method preferred over
// SetRawOptions(string(data), path, value, opts)
func SetRawBytesOptions(json []byte, path string, value []byte,
opts *Options) ([]byte, error) {
jstr := *(*string)(unsafe.Pointer(&json))
vstr := *(*string)(unsafe.Pointer(&value))
var optimistic, inplace bool
if opts != nil {
optimistic = opts.Optimistic
inplace = opts.ReplaceInPlace
}
res, err := set(jstr, path, vstr, false, false, optimistic, inplace)
if err == errNoChange {
return json, nil
}
return res, err
}