How to tie emitted events events into redux-saga?

Question

I\'m trying to use redux-saga to connect events from PouchDB to my React.js application, but I\'m struggling to figure out how to connect events emitted from PouchDB to my S

Answer 1

I had the same problem also using PouchDB and found the answers provided extremely useful and interesting. However there are many ways to do the same thing in PouchDB and I dug around a little and found a different approach which maybe easier to reason about.

If you don't attach listeners to the db.change request then it returns any change data directly to the caller and adding continuous: true to the option will cause to issue a longpoll and not return until some change has happened. So the same result can be achieved with the following

export function * monitorDbChanges() {
  var info = yield call([db, db.info]); // get reference to last change 
  let lastSeq = info.update_seq;

  while(true){
    try{
      var changes = yield call([db, db.changes], { since: lastSeq, continuous: true, include_docs: true, heartbeat: 20000 });
      if (changes){
        for(let i = 0; i < changes.results.length; i++){
          yield put({type: 'CHANGED_DOC', doc: changes.results[i].doc});
        }
        lastSeq = changes.last_seq;
      }
    }catch (error){
      yield put({type: 'monitor-changes-error', err: error})
    }
  }
}

There is one thing that I haven't got to the bottom. If I replace the for loop with change.results.forEach((change)=>{...}) then I get an invalid syntax error on the yield. I'm assuming it's something to do with some clash in the use of iterators.