Redux thunk：从分派的动作返回承诺

Question

是否可以从动作创建者返回承诺/信号，当 Redux thunk 成功调度某些动作时解决？

考虑这个动作创建者：

function doPost(data) {
    return (dispatch) => {
        dispatch({type: POST_LOADING});
        Source.doPost() // async http operation
            .then(response => {
                dispatch({type: POST_SUCCESS, payload: response})
            })
            .catch(errorMessage => {
                dispatch({type: POST_ERROR, payload: errorMessage})
            });
    }
}

当 Redux 已调度 POST_SUCCESS 或 POST_ERROR 动作时，我想在调用 doPost 动作创建者之后异步调用组件中的某些函数。一种解决方案是将回调传递给动作创建者本身，但这会使代码混乱且难以掌握和维护。我也可以在 while 循环中轮询 Redux 状态，但这会效率低下。

理想情况下，解决方案是一个承诺，当某些操作（在本例中为 POST_SUCCESS 或 POST_ERROR）被调度时，它应该解决/拒绝。

handlerFunction {
  doPost(data)
  closeWindow()
}

上面的例子应该重构，所以只有在doPost()成功时才会调用closeWindow()。

Answer 1

当然，您可以从异步操作中返回承诺：

function doPost(data) {
    return (dispatch) => {
        dispatch({type: POST_LOADING});
        // Returning promise.
        return Source.doPost() // async http operation
            .then(response => {
                dispatch({type: POST_SUCCESS, payload: response})
                // Returning response, to be able to handle it after dispatching async action.
                return response;
            })
            .catch(errorMessage => {
                dispatch({type: POST_ERROR, payload: errorMessage})
                // Throwing an error, to be able handle errors later, in component.
                throw new Error(errorMessage)
            });
    }
}

现在，dispatch 函数正在返回一个承诺：

handlerFunction {
  dispatch(doPost(data))
      // Now, we have access to `response` object, which we returned from promise in `doPost` action.
      .then(response => {
          // This function will be called when async action was succeeded.
          closeWindow();
      })
      .catch(() => {
          // This function will be called when async action was failed.
      });
}