具有 go 反射的复杂对象的 Unmarshal 方法
Unmarshal method for complex object with go reflections
我开始编写更复杂的 go 代码，我的对象节点将列表从 JSON 对象转换为具有特定键的映射。这个操作帮助我加快了我的算法。但是我现在有一个问题，我的容器结构有几个复杂的 JSON 并且我无法编写通用解决方案来实现通用解决方案。我想到的唯一方法是使用大开关盒，但我认为这不是正确的解决方案。
这是我目前的代码，其中 statusChannel 是代码中的映射，但它是 JSON 字符串中的列表
type MetricOne struct {
// Internal id to identify the metric
id int `json:"-"`
// Version of metrics format, it is used to migrate the
// JSON payload from previous version of plugin.
Version int `json:"version"`
// Name of the metrics
Name string `json:"metric_name"`
NodeId string `json:"node_id"`
Color string `json:"color"`
OSInfo *osInfo `json:"os_info"`
// timezone where the node is located
Timezone string `json:"timezone"`
// array of the up_time
UpTime []*status `json:"up_time"`
// map of informatonof channel information
ChannelsInfo map[string]*statusChannel `json:"channels_info"`
}
func (instance *MetricOne) MarshalJSON() ([]byte, error) {
jsonMap := make(map[string]interface{})
reflectType := reflect.TypeOf(*instance)
reflectValue := reflect.ValueOf(*instance)
nFiled := reflectValue.Type().NumField()
for i := 0; i < nFiled; i++ {
key := reflectType.Field(i)
valueFiled := reflectValue.Field(i)
jsonName := key.Tag.Get("json")
switch jsonName {
case "-":
// skip
continue
case "channels_info":
// TODO convert the map[string]*statusChannel in a list of statusChannel
statusChannels := make([]*statusChannel, 0)
for _, value := range valueFiled.Interface().(map[string]*statusChannel) {
statusChannels = append(statusChannels, value)
}
jsonMap[jsonName] = statusChannels
default:
jsonMap[jsonName] = valueFiled.Interface()
}
}
return json.Marshal(jsonMap)
}
func (instance *MetricOne) UnmarshalJSON(data []byte) error {
var jsonMap map[string]interface{}
err := json.Unmarshal(data, &jsonMap)
if err != nil {
log.GetInstance().Error(fmt.Sprintf("Error: %s", err))
return err
}
instance.Migrate(jsonMap)
reflectValue := reflect.ValueOf(instance)
reflectStruct := reflectValue.Elem()
// reflectType := reflectValue.Type()
for key, value := range jsonMap {
fieldName, err := utils.GetFieldName(key, "json", *instance)
if err != nil {
log.GetInstance().Info(fmt.Sprintf("Error: %s", err))
if strings.Contains(key, "dev_") {
log.GetInstance().Info("dev propriety skipped if missed")
continue
}
return err
}
field := reflectStruct.FieldByName(*fieldName)
fieldType := field.Type()
filedValue := field.Interface()
val := reflect.ValueOf(filedValue)
switch key {
case "channels_info":
statusChannelsMap := make(map[string]*statusChannel)
toArray := value.([]interface{})
for _, status := range toArray {
var statusType statusChannel
jsonVal, err := json.Marshal(status)
if err != nil {
return err
}
err = json.Unmarshal(jsonVal, &statusType)
if err != nil {
return err
}
statusChannelsMap[statusType.ChannelId] = &statusType
}
field.Set(reflect.ValueOf(statusChannelsMap))
default:
field.Set(val.Convert(fieldType))
}
}
return nil
}
当我解码对象时，我收到以下错误：
➜ go-metrics-reported git:(dev) ✗ make check
go test -v ./...
? github.com/OpenLNMetrics/go-metrics-reported/cmd/go-metrics-reported [no test files]
? github.com/OpenLNMetrics/go-metrics-reported/init/persistence [no test files]
=== RUN TestJSONSerializzation
--- PASS: TestJSONSerializzation (0.00s)
=== RUN TestJSONDeserializzation
--- FAIL: TestJSONDeserializzation (0.00s)
panic: reflect.Value.Convert: value of type map[string]interface {} cannot be converted to type *plugin.osInfo [recovered]
panic: reflect.Value.Convert: value of type map[string]interface {} cannot be converted to type *plugin.osInfo
goroutine 7 [running]:
testing.tRunner.func1.1(0x61b440, 0xc0001d69a0)
/home/vincent/.gosdk/go/src/testing/testing.go:1072 +0x30d
testing.tRunner.func1(0xc000001e00)
/home/vincent/.gosdk/go/src/testing/testing.go:1075 +0x41a
panic(0x61b440, 0xc0001d69a0)
/home/vincent/.gosdk/go/src/runtime/panic.go:969 +0x1b9
reflect.Value.Convert(0x6283e0, 0xc0001bb1a0, 0x15, 0x6b93a0, 0x610dc0, 0x610dc0, 0xc00014cb40, 0x196)
/home/vincent/.gosdk/go/src/reflect/value.go:2447 +0x229
github.com/OpenLNMetrics/go-metrics-reported/internal/plugin.(*MetricOne).UnmarshalJSON(0xc00014cb00, 0xc0001d8000, 0x493, 0x500, 0x7f04d01453d8, 0xc00014cb00)
/home/vincent/Github/OpenLNMetrics/go-metrics-reported/internal/plugin/metrics_one.go:204 +0x5b3
encoding/json.(*decodeState).object(0xc00010be40, 0x657160, 0xc00014cb00, 0x16, 0xc00010be68, 0x7b)
/home/vincent/.gosdk/go/src/encoding/json/decode.go:609 +0x207c
encoding/json.(*decodeState).value(0xc00010be40, 0x657160, 0xc00014cb00, 0x16, 0xc000034698, 0x54ec19)
/home/vincent/.gosdk/go/src/encoding/json/decode.go:370 +0x6d
encoding/json.(*decodeState).unmarshal(0xc00010be40, 0x657160, 0xc00014cb00, 0xc00010be68, 0x0)
/home/vincent/.gosdk/go/src/encoding/json/decode.go:180 +0x1ea
encoding/json.Unmarshal(0xc0001d8000, 0x493, 0x500, 0x657160, 0xc00014cb00, 0x500, 0x48cba6)
/home/vincent/.gosdk/go/src/encoding/json/decode.go:107 +0x112
github.com/OpenLNMetrics/go-metrics-reported/internal/plugin.TestJSONDeserializzation(0xc000001e00)
/home/vincent/Github/OpenLNMetrics/go-metrics-reported/internal/plugin/metric_one_test.go:87 +0x95
testing.tRunner(0xc000001e00, 0x681000)
/home/vincent/.gosdk/go/src/testing/testing.go:1123 +0xef
created by testing.(*T).Run
/home/vincent/.gosdk/go/src/testing/testing.go:1168 +0x2b3
FAIL github.com/OpenLNMetrics/go-metrics-reported/internal/plugin 0.008s
? github.com/OpenLNMetrics/go-metrics-reported/pkg/db [no test files]
? github.com/OpenLNMetrics/go-metrics-reported/pkg/graphql [no test files]
? github.com/OpenLNMetrics/go-metrics-reported/pkg/log [no test files]
? github.com/OpenLNMetrics/go-metrics-reported/pkg/utils [no test files]
FAIL
make: *** [Makefile:15: check] Error 1
谁能解释一下我如何以通用方式执行此操作？
https://play.golang.org/p/jzU_lHj1wk7
type MetricOne struct {
// ...
// Have this field be ignored.
ChannelsInfo map[string]*statusChannel `json:"-"`
}
func (m MetricOne) MarshalJSON() ([]byte, error) {
// Declare a new type using the definition of MetricOne,
// the result of this is that M will have the same structure
// as MetricOne but none of its methods (this avoids recursive
// calls to MarshalJSON).
//
// Also because M and MetricOne have the same structure you can
// easily convert between those two. e.g. M(MetricOne{}) and
// MetricOne(M{}) are valid expressions.
type M MetricOne
// Declare a new type that has a field of the "desired" type and
// also **embeds** the M type. Embedding promotes M's fields to T
// and encoding/json will marshal those fields unnested/flattened,
// i.e. at the same level as the channels_info field.
type T struct {
M
ChannelsInfo []*statusChannel `json:"channels_info"`
}
// move map elements to slice
channels := make([]*statusChannel, 0, len(m.ChannelsInfo))
for _, c := range m.ChannelsInfo {
channels = append(channels, c)
}
// Pass in an instance of the new type T to json.Marshal.
// For the embedded M field use a converted instance of the receiver.
// For the ChannelsInfo field use the channels slice.
return json.Marshal(T{
M: M(m),
ChannelsInfo: channels,
})
}
// Same as MarshalJSON but in reverse.
func (m *MetricOne) UnmarshalJSON(data []byte) error {
type M MetricOne
type T struct {
*M
ChannelsInfo []*statusChannel `json:"channels_info"`
}
t := T{M: (*M)(m)}
if err := json.Unmarshal(data, &t); err != nil {
panic(err)
}
m.ChannelsInfo = make(map[string]*statusChannel, len(t.ChannelsInfo))
for _, c := range t.ChannelsInfo {
m.ChannelsInfo[c.ChannelId] = c
}
return nil
}
我开始编写更复杂的 go 代码，我的对象节点将列表从 JSON 对象转换为具有特定键的映射。这个操作帮助我加快了我的算法。但是我现在有一个问题，我的容器结构有几个复杂的 JSON 并且我无法编写通用解决方案来实现通用解决方案。我想到的唯一方法是使用大开关盒，但我认为这不是正确的解决方案。
这是我目前的代码，其中 statusChannel 是代码中的映射，但它是 JSON 字符串中的列表
type MetricOne struct {
// Internal id to identify the metric
id int `json:"-"`
// Version of metrics format, it is used to migrate the
// JSON payload from previous version of plugin.
Version int `json:"version"`
// Name of the metrics
Name string `json:"metric_name"`
NodeId string `json:"node_id"`
Color string `json:"color"`
OSInfo *osInfo `json:"os_info"`
// timezone where the node is located
Timezone string `json:"timezone"`
// array of the up_time
UpTime []*status `json:"up_time"`
// map of informatonof channel information
ChannelsInfo map[string]*statusChannel `json:"channels_info"`
}
func (instance *MetricOne) MarshalJSON() ([]byte, error) {
jsonMap := make(map[string]interface{})
reflectType := reflect.TypeOf(*instance)
reflectValue := reflect.ValueOf(*instance)
nFiled := reflectValue.Type().NumField()
for i := 0; i < nFiled; i++ {
key := reflectType.Field(i)
valueFiled := reflectValue.Field(i)
jsonName := key.Tag.Get("json")
switch jsonName {
case "-":
// skip
continue
case "channels_info":
// TODO convert the map[string]*statusChannel in a list of statusChannel
statusChannels := make([]*statusChannel, 0)
for _, value := range valueFiled.Interface().(map[string]*statusChannel) {
statusChannels = append(statusChannels, value)
}
jsonMap[jsonName] = statusChannels
default:
jsonMap[jsonName] = valueFiled.Interface()
}
}
return json.Marshal(jsonMap)
}
func (instance *MetricOne) UnmarshalJSON(data []byte) error {
var jsonMap map[string]interface{}
err := json.Unmarshal(data, &jsonMap)
if err != nil {
log.GetInstance().Error(fmt.Sprintf("Error: %s", err))
return err
}
instance.Migrate(jsonMap)
reflectValue := reflect.ValueOf(instance)
reflectStruct := reflectValue.Elem()
// reflectType := reflectValue.Type()
for key, value := range jsonMap {
fieldName, err := utils.GetFieldName(key, "json", *instance)
if err != nil {
log.GetInstance().Info(fmt.Sprintf("Error: %s", err))
if strings.Contains(key, "dev_") {
log.GetInstance().Info("dev propriety skipped if missed")
continue
}
return err
}
field := reflectStruct.FieldByName(*fieldName)
fieldType := field.Type()
filedValue := field.Interface()
val := reflect.ValueOf(filedValue)
switch key {
case "channels_info":
statusChannelsMap := make(map[string]*statusChannel)
toArray := value.([]interface{})
for _, status := range toArray {
var statusType statusChannel
jsonVal, err := json.Marshal(status)
if err != nil {
return err
}
err = json.Unmarshal(jsonVal, &statusType)
if err != nil {
return err
}
statusChannelsMap[statusType.ChannelId] = &statusType
}
field.Set(reflect.ValueOf(statusChannelsMap))
default:
field.Set(val.Convert(fieldType))
}
}
return nil
}
当我解码对象时，我收到以下错误：
➜ go-metrics-reported git:(dev) ✗ make check
go test -v ./...
? github.com/OpenLNMetrics/go-metrics-reported/cmd/go-metrics-reported [no test files]
? github.com/OpenLNMetrics/go-metrics-reported/init/persistence [no test files]
=== RUN TestJSONSerializzation
--- PASS: TestJSONSerializzation (0.00s)
=== RUN TestJSONDeserializzation
--- FAIL: TestJSONDeserializzation (0.00s)
panic: reflect.Value.Convert: value of type map[string]interface {} cannot be converted to type *plugin.osInfo [recovered]
panic: reflect.Value.Convert: value of type map[string]interface {} cannot be converted to type *plugin.osInfo
goroutine 7 [running]:
testing.tRunner.func1.1(0x61b440, 0xc0001d69a0)
/home/vincent/.gosdk/go/src/testing/testing.go:1072 +0x30d
testing.tRunner.func1(0xc000001e00)
/home/vincent/.gosdk/go/src/testing/testing.go:1075 +0x41a
panic(0x61b440, 0xc0001d69a0)
/home/vincent/.gosdk/go/src/runtime/panic.go:969 +0x1b9
reflect.Value.Convert(0x6283e0, 0xc0001bb1a0, 0x15, 0x6b93a0, 0x610dc0, 0x610dc0, 0xc00014cb40, 0x196)
/home/vincent/.gosdk/go/src/reflect/value.go:2447 +0x229
github.com/OpenLNMetrics/go-metrics-reported/internal/plugin.(*MetricOne).UnmarshalJSON(0xc00014cb00, 0xc0001d8000, 0x493, 0x500, 0x7f04d01453d8, 0xc00014cb00)
/home/vincent/Github/OpenLNMetrics/go-metrics-reported/internal/plugin/metrics_one.go:204 +0x5b3
encoding/json.(*decodeState).object(0xc00010be40, 0x657160, 0xc00014cb00, 0x16, 0xc00010be68, 0x7b)
/home/vincent/.gosdk/go/src/encoding/json/decode.go:609 +0x207c
encoding/json.(*decodeState).value(0xc00010be40, 0x657160, 0xc00014cb00, 0x16, 0xc000034698, 0x54ec19)
/home/vincent/.gosdk/go/src/encoding/json/decode.go:370 +0x6d
encoding/json.(*decodeState).unmarshal(0xc00010be40, 0x657160, 0xc00014cb00, 0xc00010be68, 0x0)
/home/vincent/.gosdk/go/src/encoding/json/decode.go:180 +0x1ea
encoding/json.Unmarshal(0xc0001d8000, 0x493, 0x500, 0x657160, 0xc00014cb00, 0x500, 0x48cba6)
/home/vincent/.gosdk/go/src/encoding/json/decode.go:107 +0x112
github.com/OpenLNMetrics/go-metrics-reported/internal/plugin.TestJSONDeserializzation(0xc000001e00)
/home/vincent/Github/OpenLNMetrics/go-metrics-reported/internal/plugin/metric_one_test.go:87 +0x95
testing.tRunner(0xc000001e00, 0x681000)
/home/vincent/.gosdk/go/src/testing/testing.go:1123 +0xef
created by testing.(*T).Run
/home/vincent/.gosdk/go/src/testing/testing.go:1168 +0x2b3
FAIL github.com/OpenLNMetrics/go-metrics-reported/internal/plugin 0.008s
? github.com/OpenLNMetrics/go-metrics-reported/pkg/db [no test files]
? github.com/OpenLNMetrics/go-metrics-reported/pkg/graphql [no test files]
? github.com/OpenLNMetrics/go-metrics-reported/pkg/log [no test files]
? github.com/OpenLNMetrics/go-metrics-reported/pkg/utils [no test files]
FAIL
make: *** [Makefile:15: check] Error 1
谁能解释一下我如何以通用方式执行此操作？
https://play.golang.org/p/jzU_lHj1wk7
type MetricOne struct {
// ...
// Have this field be ignored.
ChannelsInfo map[string]*statusChannel `json:"-"`
}
func (m MetricOne) MarshalJSON() ([]byte, error) {
// Declare a new type using the definition of MetricOne,
// the result of this is that M will have the same structure
// as MetricOne but none of its methods (this avoids recursive
// calls to MarshalJSON).
//
// Also because M and MetricOne have the same structure you can
// easily convert between those two. e.g. M(MetricOne{}) and
// MetricOne(M{}) are valid expressions.
type M MetricOne
// Declare a new type that has a field of the "desired" type and
// also **embeds** the M type. Embedding promotes M's fields to T
// and encoding/json will marshal those fields unnested/flattened,
// i.e. at the same level as the channels_info field.
type T struct {
M
ChannelsInfo []*statusChannel `json:"channels_info"`
}
// move map elements to slice
channels := make([]*statusChannel, 0, len(m.ChannelsInfo))
for _, c := range m.ChannelsInfo {
channels = append(channels, c)
}
// Pass in an instance of the new type T to json.Marshal.
// For the embedded M field use a converted instance of the receiver.
// For the ChannelsInfo field use the channels slice.
return json.Marshal(T{
M: M(m),
ChannelsInfo: channels,
})
}
// Same as MarshalJSON but in reverse.
func (m *MetricOne) UnmarshalJSON(data []byte) error {
type M MetricOne
type T struct {
*M
ChannelsInfo []*statusChannel `json:"channels_info"`
}
t := T{M: (*M)(m)}
if err := json.Unmarshal(data, &t); err != nil {
panic(err)
}
m.ChannelsInfo = make(map[string]*statusChannel, len(t.ChannelsInfo))
for _, c := range t.ChannelsInfo {
m.ChannelsInfo[c.ChannelId] = c
}
return nil
}