/
to_event.go
153 lines (135 loc) · 4.25 KB
/
to_event.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
/*
Copyright 2021 The CloudEvents Authors
SPDX-License-Identifier: Apache-2.0
*/
package binding
import (
"bytes"
"context"
"encoding/json"
"errors"
"fmt"
"io"
"github.com/cloudevents/sdk-go/v2/binding/format"
"github.com/cloudevents/sdk-go/v2/binding/spec"
"github.com/cloudevents/sdk-go/v2/event"
"github.com/cloudevents/sdk-go/v2/types"
)
// ErrCannotConvertToEvent is a generic error when a conversion of a Message to an Event fails
var ErrCannotConvertToEvent = errors.New("cannot convert message to event")
// ErrCannotConvertToEvents is a generic error when a conversion of a Message to a Batched Event fails
var ErrCannotConvertToEvents = errors.New("cannot convert message to batched events")
// ToEvent translates a Message with a valid Structured or Binary representation to an Event.
// This function returns the Event generated from the Message and the original encoding of the message or
// an error that points the conversion error.
// transformers can be nil and this function guarantees that they are invoked only once during the encoding process.
func ToEvent(ctx context.Context, message MessageReader, transformers ...Transformer) (*event.Event, error) {
if message == nil {
return nil, nil
}
messageEncoding := message.ReadEncoding()
if messageEncoding == EncodingEvent {
m := message
for m != nil {
switch mt := m.(type) {
case *EventMessage:
e := (*event.Event)(mt)
return e, Transformers(transformers).Transform(mt, (*messageToEventBuilder)(e))
case MessageWrapper:
m = mt.GetWrappedMessage()
default:
break
}
}
return nil, ErrCannotConvertToEvent
}
e := event.New()
encoder := (*messageToEventBuilder)(&e)
_, err := DirectWrite(
context.Background(),
message,
encoder,
encoder,
)
if err != nil {
return nil, err
}
return &e, Transformers(transformers).Transform((*EventMessage)(&e), encoder)
}
// ToEvents translates a Batch Message and corresponding Reader data to a slice of Events.
// This function returns the Events generated from the body data, or an error that points
// to the conversion issue.
func ToEvents(ctx context.Context, message MessageReader, body io.Reader) ([]event.Event, error) {
messageEncoding := message.ReadEncoding()
if messageEncoding != EncodingBatch {
return nil, ErrCannotConvertToEvents
}
// Since Format doesn't support batch Marshalling, and we know it's structured batch json, we'll go direct to the
// json.UnMarshall(), since that is the best way to support batch operations for now.
var events []event.Event
return events, json.NewDecoder(body).Decode(&events)
}
type messageToEventBuilder event.Event
var _ StructuredWriter = (*messageToEventBuilder)(nil)
var _ BinaryWriter = (*messageToEventBuilder)(nil)
func (b *messageToEventBuilder) SetStructuredEvent(ctx context.Context, format format.Format, ev io.Reader) error {
var buf bytes.Buffer
_, err := io.Copy(&buf, ev)
if err != nil {
return err
}
return format.Unmarshal(buf.Bytes(), (*event.Event)(b))
}
func (b *messageToEventBuilder) Start(ctx context.Context) error {
return nil
}
func (b *messageToEventBuilder) End(ctx context.Context) error {
return nil
}
func (b *messageToEventBuilder) SetData(data io.Reader) error {
buf, ok := data.(*bytes.Buffer)
if !ok {
buf = new(bytes.Buffer)
_, err := io.Copy(buf, data)
if err != nil {
return err
}
}
if buf.Len() > 0 {
b.DataEncoded = buf.Bytes()
}
return nil
}
func (b *messageToEventBuilder) SetAttribute(attribute spec.Attribute, value interface{}) error {
if value == nil {
_ = attribute.Delete(b.Context)
return nil
}
// If spec version we need to change to right context struct
if attribute.Kind() == spec.SpecVersion {
str, err := types.ToString(value)
if err != nil {
return err
}
switch str {
case event.CloudEventsVersionV03:
b.Context = b.Context.AsV03()
case event.CloudEventsVersionV1:
b.Context = b.Context.AsV1()
default:
return fmt.Errorf("unrecognized event version %s", str)
}
return nil
}
return attribute.Set(b.Context, value)
}
func (b *messageToEventBuilder) SetExtension(name string, value interface{}) error {
if value == nil {
return b.Context.SetExtension(name, nil)
}
value, err := types.Validate(value)
if err != nil {
return err
}
return b.Context.SetExtension(name, value)
}