micro/util/reflect/struct.go

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package reflect
import (
"errors"
"fmt"
"net/url"
"reflect"
"regexp"
"strings"
"time"
)
// ErrInvalidParam specifies invalid url query params
var ErrInvalidParam = errors.New("invalid url query param provided")
var bracketSplitter = regexp.MustCompile(`\[|\]`)
var timeKind = reflect.TypeOf(time.Time{}).Kind()
type StructField struct {
Field reflect.StructField
Value reflect.Value
}
func StructFieldByTag(src interface{}, tkey string, tval string) (interface{}, error) {
sv := reflect.ValueOf(src)
if sv.Kind() == reflect.Ptr {
sv = sv.Elem()
}
if sv.Kind() != reflect.Struct {
return nil, ErrInvalidStruct
}
typ := sv.Type()
for idx := 0; idx < typ.NumField(); idx++ {
fld := typ.Field(idx)
val := sv.Field(idx)
if !val.CanSet() || len(fld.PkgPath) != 0 {
continue
}
if ts, ok := fld.Tag.Lookup(tkey); ok {
for _, p := range strings.Split(ts, ",") {
if p == tval {
if val.Kind() != reflect.Ptr && val.CanAddr() {
val = val.Addr()
}
return val.Interface(), nil
}
}
}
switch val.Kind() {
case reflect.Ptr:
if val = val.Elem(); val.Kind() == reflect.Struct {
if iface, err := StructFieldByTag(val.Interface(), tkey, tval); err == nil {
return iface, nil
}
}
case reflect.Struct:
if iface, err := StructFieldByTag(val.Interface(), tkey, tval); err == nil {
return iface, nil
}
}
}
return nil, ErrNotFound
}
func StructFieldByName(src interface{}, tkey string) (interface{}, error) {
sv := reflect.ValueOf(src)
if sv.Kind() == reflect.Ptr {
sv = sv.Elem()
}
if sv.Kind() != reflect.Struct {
return nil, ErrInvalidStruct
}
typ := sv.Type()
for idx := 0; idx < typ.NumField(); idx++ {
fld := typ.Field(idx)
val := sv.Field(idx)
if !val.CanSet() || len(fld.PkgPath) != 0 {
continue
}
if fld.Name == tkey {
if val.Kind() != reflect.Ptr && val.CanAddr() {
val = val.Addr()
}
return val.Interface(), nil
}
switch val.Kind() {
case reflect.Ptr:
if val = val.Elem(); val.Kind() == reflect.Struct {
if iface, err := StructFieldByName(val.Interface(), tkey); err == nil {
return iface, nil
}
}
case reflect.Struct:
if iface, err := StructFieldByName(val.Interface(), tkey); err == nil {
return iface, nil
}
}
}
return nil, ErrNotFound
}
// StructFields returns slice of struct fields
func StructFields(src interface{}) ([]StructField, error) {
var fields []StructField
sv := reflect.ValueOf(src)
if sv.Kind() == reflect.Ptr {
sv = sv.Elem()
}
if sv.Kind() != reflect.Struct {
return nil, ErrInvalidStruct
}
typ := sv.Type()
for idx := 0; idx < typ.NumField(); idx++ {
fld := typ.Field(idx)
val := sv.Field(idx)
if !val.CanSet() || len(fld.PkgPath) != 0 {
continue
}
switch val.Kind() {
case timeKind:
fields = append(fields, StructField{Field: fld, Value: val})
case reflect.Struct:
infields, err := StructFields(val.Interface())
if err != nil {
return nil, err
}
fields = append(fields, infields...)
default:
fields = append(fields, StructField{Field: fld, Value: val})
}
}
return fields, nil
}
// CopyDefaults for a from b
// a and b should be pointers to the same kind of struct
func CopyDefaults(a, b interface{}) {
pt := reflect.TypeOf(a)
t := pt.Elem()
va := reflect.ValueOf(a).Elem()
vb := reflect.ValueOf(b).Elem()
for i := 0; i < t.NumField(); i++ {
aField := va.Field(i)
if aField.CanSet() {
bField := vb.Field(i)
aField.Set(bField)
}
}
}
// CopyFrom sets the public members of a from b
// a and b should be pointers to structs
// a can be a different type from b
// Only the Fields which have the same name and assignable type on a
// and b will be set.
func CopyFrom(a, b interface{}) {
ta := reflect.TypeOf(a).Elem()
tb := reflect.TypeOf(b).Elem()
va := reflect.ValueOf(a).Elem()
vb := reflect.ValueOf(b).Elem()
for i := 0; i < tb.NumField(); i++ {
bField := vb.Field(i)
tbField := tb.Field(i)
name := tbField.Name
aField := va.FieldByName(name)
taField, found := ta.FieldByName(name)
if found && aField.IsValid() && bField.IsValid() && aField.CanSet() && tbField.Type.AssignableTo(taField.Type) {
aField.Set(bField)
}
}
}
func StructURLValues(src interface{}, pref string, tags []string) (url.Values, error) {
data := url.Values{}
sv := reflect.ValueOf(src)
if sv.Kind() == reflect.Ptr {
sv = sv.Elem()
}
if sv.Kind() != reflect.Struct {
return nil, ErrInvalidStruct
}
typ := sv.Type()
for idx := 0; idx < typ.NumField(); idx++ {
fld := typ.Field(idx)
val := sv.Field(idx)
if !val.CanSet() || len(fld.PkgPath) != 0 || !val.IsValid() {
continue
}
var t *tag
for _, tn := range tags {
ts, ok := fld.Tag.Lookup(tn)
if !ok {
continue
}
tp := strings.Split(ts, ",")
// special
switch tn {
case "protobuf": // special
t = &tag{key: tn, name: tp[3][5:], opts: append(tp[:3], tp[4:]...)}
default:
t = &tag{key: tn, name: tp[0], opts: tp[1:]}
}
if t.name != "" {
break
}
}
if t.name == "" {
// fallback to lowercase
t.name = strings.ToLower(fld.Name)
}
if pref != "" {
t.name = pref + "." + t.name
}
if !val.IsValid() || val.IsZero() {
continue
}
switch val.Kind() {
case reflect.Struct, reflect.Ptr:
if val.IsNil() {
continue
}
ndata, err := StructURLValues(val.Interface(), t.name, tags)
if err != nil {
return ndata, err
}
for k, v := range ndata {
data[k] = v
}
default:
switch val.Kind() {
case reflect.Slice:
for i := 0; i < val.Len(); i++ {
va := val.Index(i)
// if va.Type().Elem().Kind() != reflect.Ptr {
if va.Kind() != reflect.Ptr {
data.Set(t.name, fmt.Sprintf("%v", va.Interface()))
continue
}
switch va.Type().Elem().String() {
case "wrapperspb.BoolValue", "wrapperspb.BytesValue", "wrapperspb.StringValue":
if eva := reflect.Indirect(va).FieldByName("Value"); eva.IsValid() {
data.Add(t.name, fmt.Sprintf("%v", eva.Interface()))
}
case "wrapperspb.DoubleValue", "wrapperspb.FloatValue":
if eva := reflect.Indirect(va).FieldByName("Value"); eva.IsValid() {
data.Add(t.name, fmt.Sprintf("%v", eva.Interface()))
}
case "wrapperspb.Int32Value", "wrapperspb.Int64Value":
if eva := reflect.Indirect(va).FieldByName("Value"); eva.IsValid() {
data.Add(t.name, fmt.Sprintf("%v", eva.Interface()))
}
case "wrapperspb.UInt32Value", "wrapperspb.UInt64Value":
if eva := reflect.Indirect(va).FieldByName("Value"); eva.IsValid() {
data.Add(t.name, fmt.Sprintf("%v", eva.Interface()))
}
default:
data.Add(t.name, fmt.Sprintf("%v", val.Index(i).Interface()))
}
}
default:
data.Set(t.name, fmt.Sprintf("%v", val.Interface()))
}
}
}
return data, nil
}
// URLMap returns map of url query params
func URLMap(query string) (map[string]interface{}, error) {
var mp interface{} = make(map[string]interface{})
params := strings.Split(query, "&")
for _, part := range params {
tm, err := queryToMap(part)
if err != nil {
return nil, err
}
mp = merge(mp, tm)
}
return mp.(map[string]interface{}), nil
}
// FlattenMap expand key.subkey to nested map
func FlattenMap(a map[string]interface{}) map[string]interface{} {
// preprocess map
nb := make(map[string]interface{}, len(a))
for k, v := range a {
ps := strings.Split(k, ".")
if len(ps) == 1 {
nb[k] = v
continue
}
em := make(map[string]interface{})
em[ps[len(ps)-1]] = v
for i := len(ps) - 2; i > 0; i-- {
nm := make(map[string]interface{})
nm[ps[i]] = em
em = nm
}
if vm, ok := nb[ps[0]]; ok {
// nested map
nm := vm.(map[string]interface{})
for vk, vv := range em {
nm[vk] = vv
}
nb[ps[0]] = nm
} else {
nb[ps[0]] = em
}
}
return nb
}
/*
case reflect.String:
fn := func(c rune) bool { return c == ',' || c == ';' || c == ' ' }
slice := strings.FieldsFunc(vb.String(), fn)
if va.IsNil() {
va.Set(reflect.MakeSlice(va.Type(), len(slice), len(slice)))
}
*/
func btSplitter(str string) []string {
r := bracketSplitter.Split(str, -1)
for idx, s := range r {
if len(s) == 0 {
if len(r) > idx+1 {
copy(r[idx:], r[idx+1:])
r = r[:len(r)-1]
}
}
}
return r
}
// queryToMap turns something like a[b][c]=4 into
// map[string]interface{}{
// "a": map[string]interface{}{
// "b": map[string]interface{}{
// "c": 4,
// },
// },
// }
func queryToMap(param string) (map[string]interface{}, error) {
rawKey, rawValue, err := splitKeyAndValue(param)
if err != nil {
return nil, err
}
rawValue, err = url.QueryUnescape(rawValue)
if err != nil {
return nil, err
}
rawKey, err = url.QueryUnescape(rawKey)
if err != nil {
return nil, err
}
pieces := btSplitter(rawKey)
key := pieces[0]
// If len==1 then rawKey has no [] chars and we can just
// decode this as key=value into {key: value}
if len(pieces) == 1 {
return map[string]interface{}{
key: rawValue,
}, nil
}
// If len > 1 then we have something like a[b][c]=2
// so we need to turn this into {"a": {"b": {"c": 2}}}
// To do this we break our key into two pieces:
// a and b[c]
// and then we set {"a": queryToMap("b[c]", value)}
ret := make(map[string]interface{})
ret[key], err = queryToMap(buildNewKey(rawKey) + "=" + rawValue)
if err != nil {
return nil, err
}
// When URL params have a set of empty brackets (eg a[]=1)
// it is assumed to be an array. This will get us the
// correct value for the array item and return it as an
// []interface{} so that it can be merged properly.
if pieces[1] == "" {
temp := ret[key].(map[string]interface{})
ret[key] = []interface{}{temp[""]}
}
return ret, nil
}
// buildNewKey will take something like:
// origKey = "bar[one][two]"
// pieces = [bar one two ]
// and return "one[two]"
func buildNewKey(origKey string) string {
pieces := btSplitter(origKey)
ret := origKey[len(pieces[0])+1:]
ret = ret[:len(pieces[1])] + ret[len(pieces[1])+1:]
return ret
}
// splitKeyAndValue splits a URL param at the last equal
// sign and returns the two strings. If no equal sign is
// found, the ErrInvalidParam error is returned.
func splitKeyAndValue(param string) (string, string, error) {
li := strings.LastIndex(param, "=")
if li == -1 {
return "", "", ErrInvalidParam
}
return param[:li], param[li+1:], nil
}
// merge merges a with b if they are either both slices
// or map[string]interface{} types. Otherwise it returns b.
func merge(a interface{}, b interface{}) interface{} {
if av, aok := a.(map[string]interface{}); aok {
if bv, bok := b.(map[string]interface{}); bok {
return mergeMapIface(av, bv)
}
}
if av, aok := a.([]interface{}); aok {
if bv, bok := b.([]interface{}); bok {
return mergeSliceIface(av, bv)
}
}
va := reflect.ValueOf(a)
vb := reflect.ValueOf(b)
if (va.Type().Kind() == reflect.Slice) && (va.Type().Elem().Kind() == vb.Type().Kind() || vb.Type().ConvertibleTo(va.Type().Elem())) {
va = reflect.Append(va, vb.Convert(va.Type().Elem()))
return va.Interface()
}
return b
}
// mergeMap merges a with b, attempting to merge any nested
// values in nested maps but eventually overwriting anything
// in a that can't be merged with whatever is in b.
func mergeMapIface(a map[string]interface{}, b map[string]interface{}) map[string]interface{} {
for bK, bV := range b {
if aV, ok := a[bK]; ok {
if (reflect.ValueOf(aV).Type().Kind() == reflect.ValueOf(bV).Type().Kind()) ||
((reflect.ValueOf(aV).Type().Kind() == reflect.Slice) && reflect.ValueOf(aV).Type().Elem().Kind() == reflect.ValueOf(bV).Type().Kind()) {
nV := []interface{}{aV, bV}
a[bK] = nV
} else {
a[bK] = merge(a[bK], bV)
}
} else {
a[bK] = bV
}
}
return a
}
// mergeSlice merges a with b and returns the result.
func mergeSliceIface(a []interface{}, b []interface{}) []interface{} {
a = append(a, b...)
return a
}
type tag struct {
key string
name string
opts []string
}