How to unSubscribe Changefeeds in RethinkDB? When changes is over

Question

Cursor changeCursor = r.table("users").changes().run(conn);
for (Object change : changeCursor) {
    System.out.println(change);
}

I only need to know changes once. I know "changeCursor.close()" can stop feeds. The problem is how can i know the size of the changes this time!!

If three users added, "System.out.println(change)" execute thress times. If only one user added, "System.out.println(change)" execute one time. Then, i need to unSubscribe Changefeeds in RethinkDB.

changeCursor.toList();
changeCursor.iterator();

Not do anythings!

changeCursor.hasNext();

Alaways true!

I don't know the number of changes. I don't know when to execute the changeCursor.close() method.

Answer 1

I'm not really sure what you are asking. It seems you want to instantly get the first change, then close it.

You can do something like this with javascrip driver:

var r      = require('rethinkdb')

r.connect({
  host: 'localhost',
  port: 28015,
})
.then(function(conn) {
  return r.table('users').changes().run(conn)
})
.then(function(cursor) {
  cursor.next()
    .then(function(doc) {
      console.log(doc)
      //Ok, now right after we get the first doc, we will close the cursor
      cursor.close()
      // if we want, we can also close connection
      // cursor.close().then(conn.close())
    })
})