英文:
Unmarshal YAML into complex object which may be either struct or string
问题
尝试将YAML解组为复杂对象，例如map[string]map[interface{}]string。问题在于，我希望能够区分string和Source之间的interface{}部分，而Source是一个结构体。
显然，YAML不知道如何解组为Source结构体，所以我必须实现Unmarshaler接口：
type Unmarshaler interface {
UnmarshalYAML(value *Node) error
}
但是，我不太理解解组过程的整体情况。一般来说，我认为我必须手动遍历*yaml.Node并在每个节点上调用func UnmarshalYAML(value *Node) error。
你可以在Go Playground上查看完整的代码和运行结果：playground链接
英文:
Trying to unmarshal YAML into complex object such as map[string]map[interface{}]string.
The problem is that I want to be able to differentiate an interface{} part between string and Source which is a struct.
type Source struct {
ID string `yaml:"id"`
Name string `yaml:"name"`
LogoID string `yaml:"logoId"`
URL string `yaml:"url"`
}
type UNFT struct {
ItemMeta map[string]map[interface{}]string `yaml:"item_meta"`
// could be
// ItemMeta map[string]map[string]string `yaml:"item_meta"`
// or
// ItemMeta map[string]map[Source]string `yaml:"item_meta"`
}
Obviously YAML does not know how to unmarshal into Source struct so I have to implement Unmarshaler interface:
type Unmarshaler interface {
UnmarshalYAML(value *Node) error
}
But I don't quite understand the big picture of unmarshaling process. In general I assume that I have to manually traverse *yaml.Node and call func UnmarshalYAML(value *Node) error on every node.
package main
import (
"fmt"
"gopkg.in/yaml.v3"
)
type Source struct {
ID string `json:"id"`
Name string `json:"name"`
LogoID string `json:"logoId"`
URL string `json:"url"`
}
var data = `
unf:
item_meta:
source:
!struct
? id: "data-watch"
name: "DataWatch"
logoid: "data-watch"
url: "https"
: "product_any('SS')"
public_usage:
"": "source_any('SDF')"
"provider": "source_any('ANO')"`
type UNFT struct {
ItemMeta map[string]map[interface{}]string `yaml:"item_meta"`
}
type MetaConverterConfigT struct {
UNFT UNFT `yaml:"unf"`
}
func main() {
cfg := MetaConverterConfigT{}
err := yaml.Unmarshal([]byte(data), &cfg)
if err != nil {
fmt.Println("%w", err)
}
fmt.Println(cfg)
}
func (s *UNFT) UnmarshalYAML(n *yaml.Node) error {
var cfg map[string]map[interface{}]string
if err := n.Decode(&cfg); err != nil {
fmt.Println("%w", err)
}
return nil
}
Go playground
答案1
得分: 1
type MetaKey struct {
String string
Source Source
}
func (k *MetaKey) UnmarshalYAML(n *yaml.Node) error {
if n.Tag == "!!str" {
return n.Decode(&k.String)
}
if n.Tag == "!!map" {
return n.Decode(&k.Source)
}
return fmt.Errorf("unsupported MetaKey type")
}
// ...
type UNFT struct {
ItemMeta map[string]map[MetaKey]string `yaml:"item_meta"`
}
如果你希望保持map类型不变，即不添加自定义键类型，那么你也可以在UNFT上实现解组函数，并使用any进行重新映射：
type UNFT struct {
ItemMeta map[string]map[any]string `yaml:"item_meta"`
}
func (u *UNFT) UnmarshalYAML(n *yaml.Node) error {
var obj struct {
ItemMeta map[string]map[MetaKey]string `yaml:"item_meta"`
}
if err := n.Decode(&obj); err != nil {
return err
}
u.ItemMeta = make(map[string]map[any]string, len(obj.ItemMeta))
for k, v := range obj.ItemMeta {
m := make(map[any]string, len(v))
for k, v := range v {
if k.Source != (Source{}) {
m[k.Source] = v
} else {
m[k.String] = v
}
}
u.ItemMeta[k] = m
}
return nil
}
请注意，以上代码是对给定代码的翻译，不包含任何其他内容。
英文:
type MetaKey struct {
String string
Source Source
}
func (k *MetaKey) UnmarshalYAML(n *yaml.Node) error {
if n.Tag == "!!str" {
return n.Decode(&k.String)
}
if n.Tag == "!!map" {
return n.Decode(&k.Source)
}
return fmt.Errorf("unsupported MetaKey type")
}
// ...
type UNFT struct {
ItemMeta map[string]map[MetaKey]string `yaml:"item_meta"`
}
https://go.dev/play/p/Nhtab4l-ANT
If you need the map type to remain as is, i.e. without adding the custom key type, then you can implement the unmarshaler on UNFT as well and just do a re-mapping with any:
type UNFT struct {
ItemMeta map[string]map[any]string `yaml:"item_meta"`
}
func (u *UNFT) UnmarshalYAML(n *yaml.Node) error {
var obj struct {
ItemMeta map[string]map[MetaKey]string `yaml:"item_meta"`
}
if err := n.Decode(&obj); err != nil {
return err
}
u.ItemMeta = make(map[string]map[any]string, len(obj.ItemMeta))
for k, v := range obj.ItemMeta {
m := make(map[any]string, len(v))
for k, v := range v {
if k.Source != (Source{}) {
m[k.Source] = v
} else {
m[k.String] = v
}
}
u.ItemMeta[k] = m
}
return nil
}
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