/
event_marshal.go
203 lines (169 loc) · 5.24 KB
/
event_marshal.go
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/*
Copyright 2021 The CloudEvents Authors
SPDX-License-Identifier: Apache-2.0
*/
package event
import (
"bytes"
"encoding/base64"
"fmt"
"io"
"strings"
jsoniter "github.com/json-iterator/go"
)
// WriteJson writes the in event in the provided writer.
// Note: this function assumes the input event is valid.
func WriteJson(in *Event, writer io.Writer) error {
stream := jsoniter.ConfigFastest.BorrowStream(writer)
defer jsoniter.ConfigFastest.ReturnStream(stream)
stream.WriteObjectStart()
var ext map[string]interface{}
var dct *string
var isBase64 bool
// Write the context (without the extensions)
switch eventContext := in.Context.(type) {
case *EventContextV03:
// Set a bunch of variables we need later
ext = eventContext.Extensions
dct = eventContext.DataContentType
stream.WriteObjectField("specversion")
stream.WriteString(CloudEventsVersionV03)
stream.WriteMore()
stream.WriteObjectField("id")
stream.WriteString(eventContext.ID)
stream.WriteMore()
stream.WriteObjectField("source")
stream.WriteString(eventContext.Source.String())
stream.WriteMore()
stream.WriteObjectField("type")
stream.WriteString(eventContext.Type)
if eventContext.Subject != nil {
stream.WriteMore()
stream.WriteObjectField("subject")
stream.WriteString(*eventContext.Subject)
}
if eventContext.DataContentEncoding != nil {
isBase64 = true
stream.WriteMore()
stream.WriteObjectField("datacontentencoding")
stream.WriteString(*eventContext.DataContentEncoding)
}
if eventContext.DataContentType != nil {
stream.WriteMore()
stream.WriteObjectField("datacontenttype")
stream.WriteString(*eventContext.DataContentType)
}
if eventContext.SchemaURL != nil {
stream.WriteMore()
stream.WriteObjectField("schemaurl")
stream.WriteString(eventContext.SchemaURL.String())
}
if eventContext.Time != nil {
stream.WriteMore()
stream.WriteObjectField("time")
stream.WriteString(eventContext.Time.String())
}
case *EventContextV1:
// Set a bunch of variables we need later
ext = eventContext.Extensions
dct = eventContext.DataContentType
isBase64 = in.DataBase64
stream.WriteObjectField("specversion")
stream.WriteString(CloudEventsVersionV1)
stream.WriteMore()
stream.WriteObjectField("id")
stream.WriteString(eventContext.ID)
stream.WriteMore()
stream.WriteObjectField("source")
stream.WriteString(eventContext.Source.String())
stream.WriteMore()
stream.WriteObjectField("type")
stream.WriteString(eventContext.Type)
if eventContext.Subject != nil {
stream.WriteMore()
stream.WriteObjectField("subject")
stream.WriteString(*eventContext.Subject)
}
if eventContext.DataContentType != nil {
stream.WriteMore()
stream.WriteObjectField("datacontenttype")
stream.WriteString(*eventContext.DataContentType)
}
if eventContext.DataSchema != nil {
stream.WriteMore()
stream.WriteObjectField("dataschema")
stream.WriteString(eventContext.DataSchema.String())
}
if eventContext.Time != nil {
stream.WriteMore()
stream.WriteObjectField("time")
stream.WriteString(eventContext.Time.String())
}
default:
return fmt.Errorf("missing event context")
}
// Let's do a check on the error
if stream.Error != nil {
return fmt.Errorf("error while writing the event attributes: %w", stream.Error)
}
// Let's write the body
if in.DataEncoded != nil {
stream.WriteMore()
// We need to figure out the media type first
var mediaType string
if dct == nil {
mediaType = ApplicationJSON
} else {
// This code is required to extract the media type from the full content type string (which might contain encoding and stuff)
contentType := *dct
i := strings.IndexRune(contentType, ';')
if i == -1 {
i = len(contentType)
}
mediaType = strings.TrimSpace(strings.ToLower(contentType[0:i]))
}
isJson := mediaType == "" || mediaType == ApplicationJSON || mediaType == TextJSON
// If isJson and no encoding to base64, we don't need to perform additional steps
if isJson && !isBase64 {
stream.WriteObjectField("data")
_, err := stream.Write(in.DataEncoded)
if err != nil {
return fmt.Errorf("error while writing data: %w", err)
}
} else {
if in.Context.GetSpecVersion() == CloudEventsVersionV1 && isBase64 {
stream.WriteObjectField("data_base64")
} else {
stream.WriteObjectField("data")
}
// At this point of we need to write to base 64 string, or we just need to write the plain string
if isBase64 {
stream.WriteString(base64.StdEncoding.EncodeToString(in.DataEncoded))
} else {
stream.WriteString(string(in.DataEncoded))
}
}
}
// Let's do a check on the error
if stream.Error != nil {
return fmt.Errorf("error while writing the event data: %w", stream.Error)
}
for k, v := range ext {
stream.WriteMore()
stream.WriteObjectField(k)
stream.WriteVal(v)
}
stream.WriteObjectEnd()
// Let's do a check on the error
if stream.Error != nil {
return fmt.Errorf("error while writing the event extensions: %w", stream.Error)
}
return stream.Flush()
}
// MarshalJSON implements a custom json marshal method used when this type is
// marshaled using json.Marshal.
func (e Event) MarshalJSON() ([]byte, error) {
var buf bytes.Buffer
err := WriteJson(&e, &buf)
return buf.Bytes(), err
}