Dmitry Paloskin Dmitry Paloskin -4 years ago 780
React JSX Question

Redux saga, axios and progress event

Is there clean/short/right way to using together axios promise and uploading progress event?

Suppose I have next upload function:

function upload(payload, onProgress) {
const url = '/sources/upload';

const data = new FormData();

data.append('source', payload.file, payload.file.name);

const config = {
onUploadProgress: onProgress,
withCredentials: true
};

return axios.post(url, data, config);
}


This function returned the promise.

Also I have a saga:

function* uploadSaga(action) {
try {
const response = yield call(upload, payload, [?? anyProgressFunction ??]);
yield put({ type: UPLOADING_SUCCESS, payload: response });
} catch (err) {
yield put({ type: UPLOADING_FAIL, payload: err });
}
}


I want to receive progress events and put it by saga. Also I want to catch success (or failed) result of the axios request. Is it possible?

Thanks.

Answer Source

So I found the answer, thanks Mateusz BurzyƄski for the clarification.

We need use eventChannel, but a bit canningly.

Suppose we have api function for uploading file:

function upload(payload, onProgress) {
  const url = '/sources/upload';

  const data = new FormData();

  data.append('source', payload.file, payload.file.name);

  const config = {
    onUploadProgress: onProgress,
    withCredentials: true
  };

  return axios.post(url, data, config);
}

In saga we need to create eventChannel but put emit outside.

function createUploader(payload) {

  let emit;
  const chan = eventEmitter(emitter => {

    emit = emitter;
    return () => {}; // it's necessarily. event channel should 
                     // return unsubscribe function. In our case 
                     // it's empty function
  });

  const uploadPromise = upload(payload, (event) => {
    if (event.loaded.total === 1) {
      emit(END);
    }

    emit(event.loaded.total);
  });

  return [ uploadPromise, chan ];
}

function* watchOnProgress(chan) {
  while (true) {
    const data = yield take(chan);
    yield put({ type: 'PROGRESS', payload: data });
  }
}

function* uploadSource(action) {
  const [ uploadPromise, chan ] = createUploader(action.payload);
  yield fork(watchOnProgress, chan);

  try {
    const result = yield call(() => uploadPromise);
    put({ type: 'SUCCESS', payload: result });
  } catch (err) {
    put({ type: 'ERROR', payload: err });
  }
}
Recommended from our users: Dynamic Network Monitoring from WhatsUp Gold from IPSwitch. Free Download