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eventcontext_v1.go
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eventcontext_v1.go
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package cloudevents
import (
"errors"
"fmt"
"mime"
"sort"
"strings"
"github.com/cloudevents/sdk-go/pkg/cloudevents/types"
)
// WIP: AS OF SEP 20, 2019
const (
// CloudEventsVersionV1 represents the version 1.0 of the CloudEvents spec.
CloudEventsVersionV1 = "1.0"
)
// EventContextV1 represents the non-data attributes of a CloudEvents v1.0
// event.
type EventContextV1 struct {
// ID of the event; must be non-empty and unique within the scope of the producer.
// +required
ID string `json:"id"`
// Source - A URI describing the event producer.
// +required
Source types.URIRef `json:"source"`
// SpecVersion - The version of the CloudEvents specification used by the event.
// +required
SpecVersion string `json:"specversion"`
// Type - The type of the occurrence which has happened.
// +required
Type string `json:"type"`
// DataContentType - A MIME (RFC2046) string describing the media type of `data`.
// +optional
DataContentType *string `json:"datacontenttype,omitempty"`
// Subject - The subject of the event in the context of the event producer
// (identified by `source`).
// +optional
Subject *string `json:"subject,omitempty"`
// Time - A Timestamp when the event happened.
// +optional
Time *types.Timestamp `json:"time,omitempty"`
// DataSchema - A link to the schema that the `data` attribute adheres to.
// +optional
DataSchema *types.URI `json:"dataschema,omitempty"`
// Extensions - Additional extension metadata beyond the base spec.
// +optional
Extensions map[string]interface{} `json:"-"`
}
// Adhere to EventContext
var _ EventContext = (*EventContextV1)(nil)
// ExtensionAs implements EventContext.ExtensionAs
func (ec EventContextV1) ExtensionAs(name string, obj interface{}) error {
name = strings.ToLower(name)
value, ok := ec.Extensions[name]
if !ok {
return fmt.Errorf("extension %q does not exist", name)
}
// Only support *string for now.
if v, ok := obj.(*string); ok {
if *v, ok = value.(string); ok {
return nil
}
}
return fmt.Errorf("unknown extension type %T", obj)
}
// SetExtension adds the extension 'name' with value 'value' to the CloudEvents context.
func (ec *EventContextV1) SetExtension(name string, value interface{}) error {
if !IsAlphaNumericLowercaseLetters(name) {
return errors.New("bad key, CloudEvents attribute names MUST consist of lower-case letters ('a' to 'z') or digits ('0' to '9') from the ASCII character set")
}
name = strings.ToLower(name)
if ec.Extensions == nil {
ec.Extensions = make(map[string]interface{})
}
if value == nil {
delete(ec.Extensions, name)
return nil
} else {
v, err := types.Validate(value) // Ensure it's a legal CE attribute value
if err == nil {
ec.Extensions[name] = v
}
return err
}
}
// Clone implements EventContextConverter.Clone
func (ec EventContextV1) Clone() EventContext {
return ec.AsV1()
}
// AsV01 implements EventContextConverter.AsV01
func (ec EventContextV1) AsV01() *EventContextV01 {
ecv2 := ec.AsV02()
return ecv2.AsV01()
}
// AsV02 implements EventContextConverter.AsV02
func (ec EventContextV1) AsV02() *EventContextV02 {
ecv3 := ec.AsV03()
return ecv3.AsV02()
}
// AsV03 implements EventContextConverter.AsV03
func (ec EventContextV1) AsV03() *EventContextV03 {
ret := EventContextV03{
SpecVersion: CloudEventsVersionV03,
ID: ec.ID,
Time: ec.Time,
Type: ec.Type,
DataContentType: ec.DataContentType,
Source: types.URLRef{URL: ec.Source.URL},
Subject: ec.Subject,
Extensions: make(map[string]interface{}),
}
if ec.DataSchema != nil {
ret.SchemaURL = &types.URLRef{URL: ec.DataSchema.URL}
}
// TODO: DeprecatedDataContentEncoding needs to be moved to extensions.
if ec.Extensions != nil {
for k, v := range ec.Extensions {
k = strings.ToLower(k)
// DeprecatedDataContentEncoding was introduced in 0.3, removed in 1.0
if strings.EqualFold(k, DataContentEncodingKey) {
etv, ok := v.(string)
if ok && etv != "" {
ret.DataContentEncoding = &etv
}
continue
}
ret.Extensions[k] = v
}
}
if len(ret.Extensions) == 0 {
ret.Extensions = nil
}
return &ret
}
// AsV04 implements EventContextConverter.AsV04
func (ec EventContextV1) AsV1() *EventContextV1 {
ec.SpecVersion = CloudEventsVersionV1
return &ec
}
// Validate returns errors based on requirements from the CloudEvents spec.
// For more details, see https://github.com/cloudevents/spec/blob/v1.0-rc1/spec.md.
func (ec EventContextV1) Validate() error {
errors := []string(nil)
// id
// Type: String
// Constraints:
// REQUIRED
// MUST be a non-empty string
// MUST be unique within the scope of the producer
id := strings.TrimSpace(ec.ID)
if id == "" {
errors = append(errors, "id: MUST be a non-empty string")
// no way to test "MUST be unique within the scope of the producer"
}
// source
// Type: URI-reference
// Constraints:
// REQUIRED
// MUST be a non-empty URI-reference
// An absolute URI is RECOMMENDED
source := strings.TrimSpace(ec.Source.String())
if source == "" {
errors = append(errors, "source: REQUIRED")
}
// specversion
// Type: String
// Constraints:
// REQUIRED
// MUST be a non-empty string
specVersion := strings.TrimSpace(ec.SpecVersion)
if specVersion == "" {
errors = append(errors, "specversion: MUST be a non-empty string")
}
// type
// Type: String
// Constraints:
// REQUIRED
// MUST be a non-empty string
// SHOULD be prefixed with a reverse-DNS name. The prefixed domain dictates the organization which defines the semantics of this event type.
eventType := strings.TrimSpace(ec.Type)
if eventType == "" {
errors = append(errors, "type: MUST be a non-empty string")
}
// The following attributes are optional but still have validation.
// datacontenttype
// Type: String per RFC 2046
// Constraints:
// OPTIONAL
// If present, MUST adhere to the format specified in RFC 2046
if ec.DataContentType != nil {
dataContentType := strings.TrimSpace(*ec.DataContentType)
if dataContentType == "" {
errors = append(errors, "datacontenttype: if present, MUST adhere to the format specified in RFC 2046")
} else {
_, _, err := mime.ParseMediaType(dataContentType)
if err != nil {
errors = append(errors, fmt.Sprintf("datacontenttype: failed to parse media type, %s", err.Error()))
}
}
}
// dataschema
// Type: URI
// Constraints:
// OPTIONAL
// If present, MUST adhere to the format specified in RFC 3986
if ec.DataSchema != nil {
dataSchema := strings.TrimSpace(ec.DataSchema.String())
// empty string is not RFC 3986 compatible.
if dataSchema == "" {
errors = append(errors, "dataschema: if present, MUST adhere to the format specified in RFC 3986")
}
}
// subject
// Type: String
// Constraints:
// OPTIONAL
// MUST be a non-empty string
if ec.Subject != nil {
subject := strings.TrimSpace(*ec.Subject)
if subject == "" {
errors = append(errors, "subject: if present, MUST be a non-empty string")
}
}
// time
// Type: Timestamp
// Constraints:
// OPTIONAL
// If present, MUST adhere to the format specified in RFC 3339
// --> no need to test this, no way to set the time without it being valid.
if len(errors) > 0 {
return fmt.Errorf(strings.Join(errors, "\n"))
}
return nil
}
// String returns a pretty-printed representation of the EventContext.
func (ec EventContextV1) String() string {
b := strings.Builder{}
b.WriteString("Context Attributes,\n")
b.WriteString(" specversion: " + ec.SpecVersion + "\n")
b.WriteString(" type: " + ec.Type + "\n")
b.WriteString(" source: " + ec.Source.String() + "\n")
if ec.Subject != nil {
b.WriteString(" subject: " + *ec.Subject + "\n")
}
b.WriteString(" id: " + ec.ID + "\n")
if ec.Time != nil {
b.WriteString(" time: " + ec.Time.String() + "\n")
}
if ec.DataSchema != nil {
b.WriteString(" dataschema: " + ec.DataSchema.String() + "\n")
}
if ec.DataContentType != nil {
b.WriteString(" datacontenttype: " + *ec.DataContentType + "\n")
}
if ec.Extensions != nil && len(ec.Extensions) > 0 {
b.WriteString("Extensions,\n")
keys := make([]string, 0, len(ec.Extensions))
for k := range ec.Extensions {
keys = append(keys, k)
}
sort.Strings(keys)
for _, key := range keys {
b.WriteString(fmt.Sprintf(" %s: %v\n", key, ec.Extensions[key]))
}
}
return b.String()
}