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fix wrong code sample in helloworld-go README.md (#5746)

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yuzhipeng 2023-11-14 18:53:28 +08:00 committed by GitHub
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code-samples/eventing/helloworld/helloworld-go/README.md
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@ -34,67 +34,69 @@ cd knative-docs/code-samples/eventing/helloworld/helloworld-go
code creates a basic web server which listens on port 8080: code creates a basic web server which listens on port 8080:
```go ```go
package main
import ( import (
"context" "context"
"log" "log"
cloudevents "github.com/cloudevents/sdk-go/v2"
"github.com/google/uuid" cloudevents "github.com/cloudevents/sdk-go/v2"
"github.com/google/uuid"
) )
func receive(ctx context.Context, event cloudevents.Event)( * cloudevents.Event, cloudevents.Result) { func receive(ctx context.Context, event cloudevents.Event) (*cloudevents.Event, cloudevents.Result) {
// Here is where your code to process the event will go. // Here is where your code to process the event will go.
// In this example we will log the event msg // In this example we will log the event msg
log.Printf("Event received. \n%s\n", event) log.Printf("Event received. \n%s\n", event)
data: = & HelloWorld {} data := &HelloWorld{}
if err: = event.DataAs(data); if err := event.DataAs(data); err != nil {
err != nil { log.Printf("Error while extracting cloudevent Data: %s\n", err.Error())
log.Printf("Error while extracting cloudevent Data: %s\n", err.Error()) return nil, cloudevents.NewHTTPResult(400, "failed to convert data: %s", err)
return nil, cloudevents.NewHTTPResult(400, "failed to convert data: %s", err) }
} log.Printf("Hello World Message from received event %q", data.Msg)
log.Printf("Hello World Message from received event %q", data.Msg)
// Respond with another event (optional) // Respond with another event (optional)
// This is optional and is intended to show how to respond back with another event after processing. // This is optional and is intended to show how to respond back with another event after processing.
// The response will go back into the knative eventing system just like any other event // The response will go back into the knative eventing system just like any other event
newEvent: = cloudevents.NewEvent() newEvent := cloudevents.NewEvent()
newEvent.SetID(uuid.New().String()) // Setting the ID here is not necessary. When using NewDefaultClient the ID is set
newEvent.SetSource("knative/eventing/samples/hello-world") // automatically. We set the ID anyway so it appears in the log.
newEvent.SetType("dev.knative.samples.hifromknative") newEvent.SetID(uuid.New().String())
if err: = newEvent.SetData(cloudevents.ApplicationJSON, HiFromKnative { newEvent.SetSource("knative/eventing/samples/hello-world")
Msg: "Hi from helloworld-go app!" newEvent.SetType("dev.knative.samples.hifromknative")
}); if err := newEvent.SetData(cloudevents.ApplicationJSON, HiFromKnative{Msg: "Hi from helloworld-go app!"}); err != nil {
err != nil { return nil, cloudevents.NewHTTPResult(500, "failed to set response data: %s", err)
return nil, cloudevents.NewHTTPResult(500, "failed to set response data: %s", err) }
} log.Printf("Responding with event\n%s\n", newEvent)
log.Printf("Responding with event\n%s\n", newEvent) return &newEvent, nil
return &newEvent, nil
} }
func main() { func main() {
log.Print("Hello world sample started.") log.Print("Hello world sample started.")
c, err: = cloudevents.NewDefaultClient() c, err := cloudevents.NewDefaultClient()
if err != nil { if err != nil {
log.Fatalf("failed to create client, %v", err) log.Fatalf("failed to create client, %v", err)
} }
log.Fatal(c.StartReceiver(context.Background(), receive)) log.Fatal(c.StartReceiver(context.Background(), receive))
} }
``` ```
1. Create a new file named `eventschemas.go` and paste the following code. This 1. Create a new file named `eventschemas.go` and paste the following code. This
defines the data schema of the CloudEvents. defines the data schema of the CloudEvents.
```go ```go
package main package main
// HelloWorld defines the Data of CloudEvent with type=dev.knative.samples.helloworld // HelloWorld defines the Data of CloudEvent with type=dev.knative.samples.helloworld
type HelloWorld struct { type HelloWorld struct {
// Msg holds the message from the event // Msg holds the message from the event
Msg string `json:"msg,omitempty,string"` Msg string `json:"msg,omitempty"`
} }
// HiFromKnative defines the Data of CloudEvent with type=dev.knative.samples.hifromknative // HiFromKnative defines the Data of CloudEvent with type=dev.knative.samples.hifromknative
type HiFromKnative struct { type HiFromKnative struct {
// Msg holds the message from the event // Msg holds the message from the event
Msg string `json:"msg,omitempty,string"` Msg string `json:"msg,omitempty"`
} }
``` ```