Gmail API - Invalid topicName does not match projects/../topics/*

I am exploring the Google Cloud PubSub these days. I am working on a project where I have to listen for the User's Gmail Inbox and then process the new emails as they arrive.

I used a Gmail Client API to add the watch on user's Gmail. I encountered the following exception

Exception in thread "main" com.google.api.client.googleapis.json.GoogleJsonResponseException: 400 Bad Request
{
  "code" : 400,
  "errors" : [ {
    "domain" : "global",
    "message" : "Invalid topicName does not match projects/modular-botany-234216/topics/*",
    "reason" : "invalidArgument"
  } ],
  "message" : "Invalid topicName does not match projects/modular-botany-234216/topics/*"
}
at com.google.api.client.googleapis.json.GoogleJsonResponseException.from(GoogleJsonResponseException.java:146)


Solution

After a bit of struggle and google, I found that I have created the credentails.json file for another project instead of the one I was using in the watch call

       WatchRequest watchRequest = new WatchRequest();

        List<String> labels = new ArrayList<String>();

        labels.add("INBOX");

        watchRequest.setLabelIds(labels);

        watchRequest.setTopicName("projects/modular-botany-234216/topics/GmailMessage");

STEP 1

Open the credentails page i.e. https://console.developers.google.com/apis/credentials

STEP 2

Select the Project from the list 

STEP 3

• Select Create Credentials
• Select OAuth 2.0 client ID

STEP 4

• Enter the Name
• Authorized Redirect URLs

You are done.