CODEWITHSUNDEEP
typescriptreduxreact-reduxmiddleware
Prozak
Prozak

Reputation: 303

Creating React middleware that listens for errors on all actions

I am writing my first custom middleware and slightly clueless to what is going on. My objective is to check if any action receives a network error, if so console.log it.

import { Middleware, MiddlewareAPI, Dispatch, Action } from "redux"

export const logger: Middleware = <S>(api: MiddlewareAPI<S>) => (
  next: Dispatch<S>
) => <A extends Action>(action: A): A => {
  console.log("Before")
  const result = next(action)
  if (action.type.HTTPStatus) {
    console.log("HERE IS AN ERROR")
  }

  console.log("After", api.getState())
  return result
}

The action.type.HTTPStatus does not work. I've been trying to filter the actions based on action.type but am not sure how to do it. It seems everything I attach to action.type.whatever doesn't break anything but doesn't do anything either. Here is an example of an API action. 

export const getTelevisionChannels = (televisionIds: string[]) => async (
  dispatch: Dispatch<AppState>
) => {
  try {
    const response = await API.post(
      "/Channels/querys/status",
      { body: JSON.stringify({ televisionIds }) },
      true,
      dispatch
    )
    const televisionChannels = await response.json()
    televisionChannels.map((televisionChannel: any) =>
      dispatch(
        getChannelsSuccess(televisionChannel.televisionId, televisionChannel.channels)
      )
    )
  } catch (err) {
    dispatch(push("/404"))
    console.log(err)
  }
}

I do have a goal to deal with this error with a separate Dispatch component with its own reducer and action but first I need to be able to get this middleware working.

Upvotes: 0

Views: 867

Answers (1)

windmaomao
windmaomao

Reputation: 7671

I wrote a apiMiddleware recently, so here is the simplified version. What you want is to grab the error when there's an API issue and then dispatch an error action { type: errorType }. Then you need a reducer to process these changes. 

export default function createApiMiddleware(axios) {
  return ({ getState }) => next => action => {
    const api = action[CALL_API]
    if (!api) {
      return next(action)
    }

    const obj = {}
    const { actionPrefix, types, method, host, url, onSuccess, ...props } = api
    const prefix = actionPrefix || ''
    const [startedType, successType, errorType] = types ? types : ACTION_KEYS.map(v => prefix + v)

    next({ type: startedType })

    obj.method = method || 'get'
    obj.url = host ? (host + url) : url

    const onSuccessOps = Object.assign({}, defaultOnSuccess, onSuccess)
    const { responseBody } = onSuccessOps

    const afterSuccess = (payload) => {
      const { customActions } = onSuccessOps
      customActions.forEach(type => {
        next({ type, payload })
      })      
    }

    return axios(
      Object.assign(obj, { ...props })
    ).then(res => {
      const payload = responseBody(res)      
      next({ type: successType, payload })
      afterSuccess(payload)
    }, err => {
      next({ type: errorType, payload: err })
    })
  }
}

export default function createApiReducer(actionPrefix, options) {
  const ops = Object.assign({}, defaultOptions, options)
  const initialState = {
    data: [],
    isLoaded: false,
    isLoading: ops.loadOnStart,
    error: null,
  }

  return (state = initialState, action) => {
    const custom = ops.customActions[action.type]
    if (custom) {
      return custom(state)
    }

    switch (action.type) {
      case `${actionPrefix}Loading`:
        return {
          ...state,
          isLoading: true,
          error: null
        }
      case `${actionPrefix}Error`:
        return {
          ...state,
          isLoading: false,
          error: action.payload
        }
      case `${actionPrefix}Success`:
        return {
          ...state,
          isLoading: false,
          isLoaded: true,
          error: null,
          data: action.payload
        }
      default:
        return state
    }
  }
}

Since you want a middleware, therefore I put it here as a reference, normally you would just want to dispatch couple of actions for one API in any redux text book. Hope this helps.

Upvotes: 1

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