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package jsonrpc2
import (
"encoding/json"
"errors"
)
// Response represents a JSON-RPC response. See
// http://www.jsonrpc.org/specification#response_object.
type Response struct {
ID ID `json:"id"`
Result *json.RawMessage `json:"result,omitempty"`
Error *Error `json:"error,omitempty"`
// Meta optionally provides metadata to include in the response.
//
// NOTE: It is not part of spec. However, it is useful for propagating
// tracing context, etc.
Meta *json.RawMessage `json:"meta,omitempty"`
// SPEC NOTE: The spec says "If there was an error in detecting
// the id in the Request object (e.g. Parse error/Invalid
// Request), it MUST be Null." If we made the ID field nullable,
// then we'd have to make it a pointer type. For simplicity, we're
// ignoring the case where there was an error in detecting the ID
// in the Request object.
}
// MarshalJSON implements json.Marshaler and adds the "jsonrpc":"2.0"
// property.
func (r Response) MarshalJSON() ([]byte, error) {
if (r.Result == nil || len(*r.Result) == 0) && r.Error == nil {
return nil, errors.New("can't marshal *jsonrpc2.Response (must have result or error)")
}
type tmpType Response // avoid infinite MarshalJSON recursion
b, err := json.Marshal(tmpType(r))
if err != nil {
return nil, err
}
b = append(b[:len(b)-1], []byte(`,"jsonrpc":"2.0"}`)...)
return b, nil
}
// UnmarshalJSON implements json.Unmarshaler.
func (r *Response) UnmarshalJSON(data []byte) error {
type tmpType Response
// Detect if the "result" field is JSON "null" or just not present
// by seeing if the field gets overwritten to nil.
*r = Response{Result: &json.RawMessage{}}
if err := json.Unmarshal(data, (*tmpType)(r)); err != nil {
return err
}
if r.Result == nil { // JSON "null"
r.Result = &jsonNull
} else if len(*r.Result) == 0 {
r.Result = nil
}
return nil
}
// SetResult sets r.Result to the JSON representation of v. If JSON
// marshaling fails, it returns an error.
func (r *Response) SetResult(v interface{}) error {
b, err := json.Marshal(v)
if err != nil {
return err
}
r.Result = (*json.RawMessage)(&b)
return nil
}
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