70 lines
1.7 KiB
Go
70 lines
1.7 KiB
Go
// Package jsonhooks adds hooks that are automatically called before JSON marshaling (PreMarshalJSON) and
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// after JSON unmarshaling (PostUnmarshalJSON). It does not do so recursively.
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package jsonhooks
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import (
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"encoding/json"
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"reflect"
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)
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// Marshal wraps encoding/json.Marshal, calls v.PreMarshalJSON() if it exists
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func Marshal(v interface{}) ([]byte, error) {
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if ImplementsPreJSONMarshaler(v) {
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err := v.(PreJSONMarshaler).PreMarshalJSON()
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if err != nil {
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return nil, err
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}
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}
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return json.Marshal(v)
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}
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// Unmarshal wraps encoding/json.Unmarshal, calls v.PostUnmarshalJSON() if it exists
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func Unmarshal(data []byte, v interface{}) error {
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err := json.Unmarshal(data, v)
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if err != nil {
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return err
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}
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if ImplementsPostJSONUnmarshaler(v) {
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err := v.(PostJSONUnmarshaler).PostUnmarshalJSON()
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if err != nil {
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return err
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}
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}
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return nil
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}
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// PreJSONMarshaler infers support for the PreMarshalJSON pre-hook
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type PreJSONMarshaler interface {
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PreMarshalJSON() error
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}
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// ImplementsPreJSONMarshaler checks for support for the PreMarshalJSON pre-hook
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func ImplementsPreJSONMarshaler(v interface{}) bool {
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value := reflect.ValueOf(v)
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if !value.IsValid() {
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return false
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}
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_, ok := value.Interface().(PreJSONMarshaler)
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return ok
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}
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// PostJSONUnmarshaler infers support for the PostUnmarshalJSON post-hook
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type PostJSONUnmarshaler interface {
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PostUnmarshalJSON() error
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}
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// ImplementsPostJSONUnmarshaler checks for support for the PostUnmarshalJSON post-hook
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func ImplementsPostJSONUnmarshaler(v interface{}) bool {
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value := reflect.ValueOf(v)
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if value.Kind() == reflect.Ptr && value.IsNil() {
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return false
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}
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_, ok := value.Interface().(PostJSONUnmarshaler)
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return ok
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}
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