Overcome design problem with shouldRun

[fnune]

Currently shouldRun and crudReducer don't play nice together. shouldRun runs after the crudReducer has already cleaned up some parts of the store, so the data is invalid.

Proposal:
// ENSURE_SINGLE
// FETCH_SINGLE

Running ensure will do the check with shouldRun and then result in either FETCH_SINGLE or nothing. Using fetchSingle directly will avoid the shouldRun check and will "force" the saga to run.

The ensure action should only be generated in crudActionsNamespace and not in the more generic actionsNamespace.

[fnune]

Maybe the best idea is to drop shouldRun completely because:

• It introduces a lot of design problems.
• It can also be handled in a lean way in the components.

[fnune]

Maybe make the saga responsible for managing loading states (which are the main reason why shouldRun and crudReducer don't work well together). Which part of the state to change is the responsibility of the saga.

[tomhoule]

Detailed proposal:

• We create a very simple loadingReducer, a dictionary of type ActionType -> boolean
• shouldRun runs, decides if the effect should run, dispatches SET_LOADING with the action type as a payload if so.
• On success or failure, UNSET_LOADING with the action type

We should also warn users of the library not to do things they might regret on FETCH actions in reducers.

[peterfication]

Or we could extract the shouldRun in a custom action/saga that dispatches FETCH if it is needed. So we only have one extra action type.

[tomhoule]

export const configurePerform = failureHandler => function* (effect, action) => {
  try {
    const response = yield effect
    yield put({
        type: action.meta.successAction,
        payload: response,
        meta: { originalAction: action },
    })
  } catch (error) {
    yield failureHandler(error, action, action.meta.failureAction)
  }
}


// shouldRun would look something like that inside a saga
if (condition) {
    yield put(campaignsActions.cancelLoading('index'))
    return
}



export const simplePerform = configurePerform(defaultFailureHandler)


const configureCrudReducer = extractors => (state, action, actionTypes) => {
}

const defaultExtractors = {
    index: (action, state) => action.payload,
    meta: (action, state) => action.payload,
    error: (action, state) => action.payload,
    show: (action, state) => action.payload,
}

-> we need to add a CANCEL_LOADING action to crudActionsNamespace