CODEWITHSUNDEEP
gogoogle-cloud-platformgoogle-cloud-functionspublish-subscribegoogle-cloud-pubsub
Valentyn
Valentyn

Reputation: 612

JSON data as message for PubSub

I have written the following code according to the Google "Publishing messages to topics" Guide:

import (
        "context"
        "fmt"
        "io"
        "cloud.google.com/go/pubsub"
)

func publishMessage(w io.Writer, projectID, topicID) error {
        msg := `{
                  "source":"test_source",
                  "data": {
                          "jobId": "123",
                          "recordCount": 10000
                          }
                }`
        ctx := context.Background()
        client, err := pubsub.NewClient(ctx, projectID)
        if err != nil {
                return fmt.Errorf("pubsub.NewClient: %v", err)
        }

        t := client.Topic(topicID)

        result := t.Publish(ctx, &pubsub.Message{Data: []byte(msg)})
        id, err := result.Get(ctx)
        if err != nil {
                return fmt.Errorf("Get: %v", err)
        }
        fmt.Fprintf(w, "Published a message; msg ID: %v\n", id)
        return nil
}

But each time I receive the error in logs of my Cloud Function:

"com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: expected BEGIN_OBJECT, but was STRING"

I'd be grateful if you have any ideas on how to fix that.

Upvotes: 0

Views: 5663

Answers (1)

Martin Zeitler
Martin Zeitler

Reputation: 76649

This isn't really a Go question, but rather a NodeJS question. Despite the question is completely missing the Cloud Function's code, I still can tell what is wrong with it: Since you are pushing string instead of JSON, you have to use JSON.parse(string); before being able to use GSON on it.

If you want a Go answer, you'd probably need to push JSON, to begin with.

In Go one can encode JSON with json.Marshal() (data object could be defined as struct):

type Message struct {
    source string
    data object
}
msg := Message{ ... }
payload, err := json.Marshal(msg)

It doesn't really matter on which end you'd fix the problem created by pushing a JSON string instead of a JSON. The second one approach might probably be a tad better than the first one (in terms of already providing the expected format, instead of messing around later on). This is based upon, that a JSON and a JSON string are not the same thing (not even with identical content).

Upvotes: 1

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