Redux - Update store with same function from different files - redux

Question

being rather new to react.js + redux, I'm facing the following conundrum:
I have multiple files, which need to update the store in exactly the same way, based on the stores current state. Currently I simply copy-paste the same code (along with the needed mapStateToProps), which goes again DRY.
Similar to something like the below, where getData is an Ajax call living in the actions file and props.timeAttribute is coming from mapStateToProps:
props.getData(props.timeAttribute).then((newState) => {
console.log(newState)
})
Would a function like that go in the actions file? Can the current state be read from within that actions file? Or does one normally create some sort of helperFile.js in which a function like that lives and is being called from other files?
Thanks!

Answer 1

If your file is executing the same action, then yes, you would put the action creator in a separate file and export it. In theory, you can put state in an action by passing the state as a parameter, but the philosophy behind an action is that it announces to your application that SOMETHING HAPPENED (as denoted by the type property on the return value of the action function). The reducer function responsible for handling that type subsequently updates the state.
You can access the current state of the store inside of an action creator like this:
export const testAction = (someParam) => {
return (dispatch, getState) => {
const {
someState,
} = getState(); //getState gets the entire state of your application
//do something with someState and then run the dispatch function like this:
dispatch(() => {type: ACTION_TYPE, payload: updatedState})
}
I like this approach because it encapsulates all the logic for accessing state inside of the one function that will need to access it.
DO NOT modify the state inside of the action creator though! This should be read only. The state of your application should only be updated through your reducer functions.

Answer 2

Yes, it is recommended to maintain a separate file for your actions.
Below is an example of how i use an action to fetch information and dispatch an action.
export const fetchComments = () => (dispatch) => {
console.log("Fetch Comment invoked");
/*you can use your Ajax getData call instead of fetch.
Can also add parameters if you need */
return fetch(baseUrl + 'comments')
.then(response => {
if (response.ok){
return response;
}
else {
var error = new Error('Error ' + response.status + ': ' + response.statusText);
error.response = response;
throw error;
}
},
error => {
var errmess = new Error(error.message);
throw errmess;
})
.then(response => response.json())
.then(comments => dispatch(addComments(comments)))
.catch(error => dispatch(commentsFailed(error.message)));
}
/* Maintain a separate file called ActionTypes.js where you can store all the ActionTypes as Strings. */
export const addComments = (comments) => ({
type : ActionTypes.ADD_COMMENTS,
payload : comments
});
export const comments = (errMess) => ({
type : ActionTypes.COMMENTS_FAILED,
payload : errMess
});
Once, you receive dispatch an action, you need an reducer to capture the action and make changes to your store.
Note that this reducer must be a pure function.
export const comments = (state = { errMess: null, comments:[]}, action) => {
console.log("inside comments");
switch (action.type) {
case ActionTypes.ADD_COMMENTS:
return {...state, errMess: null, comments: action.payload};
case ActionTypes.COMMENTS_FAILED:
return {...state, errMess: action.payload};
default:
return state;
}
};
Don't forget to combine the reducers in the configureStore().
const store = createStore(
combineReducers({
comments
}),
applyMiddleware(thunk,logger)
);
In your components where you use the Actions, use
const mapDispatchToProps = dispatch => ({
fetchComments : () => dispatch(fetchComments()),
})
Note to export the component as
export default connect(mapStateToProps,mapDispatchToProps)(Component);