I have the following code
store/index.js
const DEFAULT_STATE = {
auth: { isAuthenticated: false },
error: { message: null },
tracks: [],
uploadedTrack: {}
};
store/reducers/index.js
import auth from './auth';
import error from './error';
import {tracks, uploadedTrack} from './tracks';
export default combineReducers({
auth,
tracks,
uploadedTrack,
error
});
store/reducers/tracks.js
import {UPLOADED_TRACK, SET_CURRENT_USER_TRACK} from '../actionTypes';
export const tracks = (state = [], action) => {
switch(action.type) {
case SET_CURRENT_USER_TRACK:
return action.tracks;
default:
return state;
}
}
export const uploadedTrack = (state = {}, action) => {
switch(action.type) {
case UPLOADED_TRACK:
return action.track;
default:
return state;
}
};
store/actions/tracks.js
export const setTrack = tracks => ({
type: SET_CURRENT_USER_TRACK,
tracks
});
export const setUploadedTrack = track => ({
type: UPLOADED_TRACK,
track
});
export const getUserTrack = () => {
return async dispatch => {
try {
const {token, ...tracks} = await api.call('get', 'tracks/user');
dispatch(setTrack(tracks));
dispatch(removeError());
} catch (err) {
const {error} = err.response.data;
dispatch(addError(error.message));
}
};
};
components/trackList.jsx
componentDidMount() {
const {getUserTrack} = this.props;
getUserTrack();
}
render() {
var {authType} = this.props;
const {auth} = this.props;
const {tracks} = this.props;
console.log("Track: ", tracks)
All seems works because my "tracks" on Redux store contains my list of six tracks, but when i try to print this information from the "tracks" variable on the console this print "undefined".
The strange things is that my "call" on the console contains my six tracks...
Can you help me?
I don't know where is my errors, i try to apply the solutions find on the web but nothing working.
Can you show how you map your redux state to your component ? If your redux store store contains your six tracks but you can't display them in your react component, the problem is probably how you bind your store to your component (When you call your connect() in your components/trackList.jsx).
Related
I’m working on a little proof of concept project, using React and Redux, and useSelector and useDispatch hooks. I’m trying to fetch some data asynchronously and I use thunks for that. I think I'm conceptually missing something. Even though my state works as expected, I can not get my data from api using useSelector.
Here is the code. My action:
import axios from "axios";
export const API_FETCH_POSTS = 'API_FETCH_POSTS';
export const fetchPosts = (postId) => { // to simulate post request
return (dispatch) => {
let baseUrl = 'https://jsonplaceholder.typicode.com/';
let postFix = 'comments?postId=';
let url = `${baseUrl}${postFix}${postId}`;
axios.get(url)
.then(response => {
const data = response.data;
console.log(JSON.stringify(data)); // work!
dispatch(fetchPostsSuccess(data));
});
}
};
const fetchPostsSuccess = posts => {
return {
type: API_FETCH_POSTS,
payload: posts
}
};
My reducer:
import {API_FETCH_POSTS} from "./apiActions";
const initialState = {
getPostsReq : {
posts: [],
}
};
const apiReducer = (state = initialState, action) => {
let getPostsReq;
switch (action.type) {
case API_FETCH_POSTS:
getPostsReq = {
posts: [...state.getPostsReq.posts]
};
return {
...state,
getPostsReq
};
default: return state;
}
};
export default apiReducer;
And rootReducer:
import {combineReducers} from 'redux';
import apiReducer from "./api/apiReducer";
export default combineReducers({
api: apiReducer
})
And store:
const initialState = {};
const store = createStore(
rootReducer,
initialState,
composeWithDevTools(
applyMiddleware(thunk)
)
);
export default store;
I have a problem with my React component:
function PostContainer(props) {
const posts = useSelector(state => state.api.getPostsReq.posts);
const dispatch = useDispatch();
const logPosts = () => {
{/*why doesn't this line work???*/}
console.log(JSON.stringify(posts));
}
return (
<div>
<button onClick={() => {
dispatch(fetchPosts(1));
logPosts();
}}>Fetch Posts</button>
<div>
{/*why doesn't this line work???*/}
{posts.map(post => <p>{post.body}</p>)}
</div>
</div>
);
}
export default PostContainer;
I expect that after I press the button, the function fetchPosts gets dispatched and because I use thunk I shouldn’t have any problems with asynchronicity. But by some reason I can’t get my state, using useSelector() hook. I can neither render the state, nor log it in the console.
What am I missing here?
Here is the whole code if it is more convenient - https://github.com/JavavaJ/use-select-problem
Problem: Not Storing Posts
Your selector is fine, it's your reducer that's the problem! You dispatch an action which has an array of posts in the payload:
const fetchPostsSuccess = posts => {
return {
type: API_FETCH_POSTS,
payload: posts
}
};
But when you respond to this action in the reducer, you completely ignore the payload and instead just return the same posts that you already had:
const apiReducer = (state = initialState, action) => {
let getPostsReq;
switch (action.type) {
case API_FETCH_POSTS:
getPostsReq = {
posts: [...state.getPostsReq.posts]
};
return {
...state,
getPostsReq
};
default: return state;
}
};
Solution: Add Posts from Action
You can rewrite your reducer like this to append the posts using Redux immutable update patterns.
const apiReducer = (state = initialState, action) => {
switch (action.type) {
case API_FETCH_POSTS:
return {
...state,
getPostsReq: {
...state.getPostsReq,
posts: [...state.getPostsReq.posts, ...action.payload]
}
};
default:
return state;
}
};
It's a lot easier if you use Redux Toolkit! With the toolkit you can "mutate" the draft state in your reducers, so we don't need to copy everything.
const apiReducer = createReducer(initialState, {
[API_FETCH_POSTS]: (state, action) => {
// use ... to push individual items separately
state.getPostsReq.posts.push(...action.payload);
}
});
I am migrating my component from a class component to a functional component using hooks. I need to access the states with useSelector by triggering an action when the state mounts. Below is what I have thus far. What am I doing wrong? Also when I log users to the console I get the whole initial state ie { isUpdated: false, users: {}}; instead of just users
reducers.js
const initialState = {
isUpdated: false,
users: {},
};
const generateUsersObject = array => array.reduce((obj, item) => {
const { id } = item;
obj[id] = item;
return obj;
}, {});
export default (state = { ...initialState }, action) => {
switch (action.type) {
case UPDATE_USERS_LIST: {
return {
...state,
users: generateUsersObject(dataSource),
};
}
//...
default:
return state;
}
};
action.js
export const updateUsersList = () => ({
type: UPDATE_USERS_LIST,
});
the component hooks I am using
const users = useSelector(state => state.users);
const isUpdated = useSelector(state => state.isUpdated);
const dispatch = useDispatch();
useEffect(() => {
const { updateUsersList } = actions;
dispatch(updateUsersList());
}, []);
first, it will be easier to help if the index/store etc will be copied as well. (did u used thunk?)
second, your action miss "dispatch" magic word -
export const updateUsersList = () =>
return (dispatch, getState) => dispatch({
type: UPDATE_USERS_LIST
});
it is highly suggested to wrap this code with { try } syntax and be able to catch an error if happened
third, and it might help with the console.log(users) error -
there is no need in { ... } at the reducer,
state = intialState
should be enough. this line it is just for the first run of the store.
and I don't understand where { dataSource } comes from.
I have set up react/redux so that when component mounts, it will render the information. When I console log this.props.heroes.data, I get a value of [{id:1,heroname:'Batman',realname:'Bruce Wayne'},{id:2,heroname:'Nightwing',realname:'Richard Grayson'}]. When i try to map this.props.hero.data, I get an undefined statement and the console.log turns into an empty array.
My stack is React,Redux,Express,PostgreSQL
I tried playing around with this.props.heroes did some console logs and was able to go from undefined completely to undefined with an empty array.
My heroes component page:
class AllHeroes extends Component {
async componentDidMount() {
await this.props.getHeroes();
}
render() {
const heroes = this.props.heroes;
console.log("heroesreal", heroes);
console.log(typeof heroes);
if (!this.props.heroes) return "LOADING";
else {
return (
<div>
<h1>Placeholder</h1>
{heroes.data.map(hero => {
return <div key={hero.id}>{hero.heroname}</div>;
})}
</div>
);
}
}
}
const mapStateToProps = state => ({ heroes: state.heroes });
const mapDispatchToProps = dispatch => ({
getHeroes: () => dispatch(getHeroes())
});
export default connect(
mapStateToProps,
mapDispatchToProps
)(AllHeroes);
My redux for heroes:
const GOT_HEROES = "GOT_HEROES";
const gotHeroes = heroes => ({ type: GOT_HEROES, heroes });
export const getHeroes = () => async dispatch => {
const { data } = await axios.get("/api/heroes");
dispatch(gotHeroes(data));
};
const heroesReducer = (heroes = [], action) => {
switch (action.type) {
case GOT_HEROES:
return action.heroes;
case DELETE_HERO:
const heroId = action.id;
return heroes.filter(hero => hero.id !== heroId);
default:
return heroes;
}
};
const combinedReducers = combineReducers({
heroes: heroesReducer,
villains: villainsReducer,
hero: heroReducer
// villain: villainReducer
});
I don't believe i have any store connectivity issue as I had an error for that before and i fixed it by putting a provider and store in my very top component.
Expected page to render: Batman Nightwing but got undefined: []. Thank you in advance for any help!
Your reducer should look like this
const GOT_HEROES = "GOT_HEROES";
const gotHeroes = heroes => ({ type: GOT_HEROES, heroes });
export const getHeroes = () => async dispatch => {
const { data } = await axios.get("/api/heroes");
dispatch(gotHeroes(data));
};
const state = {
heroes: []
}
const heroesReducer = (heroes = [], action) => {
switch (action.type) {
case GOT_HEROES:
return { heroes: action.heroes , ...state };
case DELETE_HERO:
const heroId = action.id;
const { heroes } = state
newHeroes = heroes.filter(hero => hero.id !== heroId);
return { heroes: newHeroes, ...state }
default:
return state;
}
};
const combinedReducers = combineReducers({
heroes: heroesReducer,
villains: villainsReducer,
hero: heroReducer
// villain: villainReducer
});
Thats how you can add more data in single reducer as well
Plz refer these
https://redux.js.org/recipes/structuring-reducers/refactoring-reducer-example
I'm not sure why I'm forced to do a check if actions exists in my reducer. Could it be because we are using async await in our actions / API methods?
Reducer
export const partyReducer = (state = initState, action) => {
if (action) { // <-- should not need this
switch (action.type) {
case Actions.SET_ROLES: {
const roles = formatRoles(action.roles);
return {
...state,
roles
};
}
default:
return state;
}
}
return state;
};
export default partyReducer;
Actions
import {getRoles} from '../shared/services/api';
export const Actions = {
SET_ROLES: 'SET_ROLES'
};
export const fetchRoles = () => async dispatch => {
try {
const response = await getRoles();
const roles = response.data;
dispatch({
type: Actions.SET_ROLES,
roles
});
} catch (error) {
dispatch({
type: Actions.SET_ROLES,
roles: []
});
}
};
Component that dispatches the action:
componentDidMount() {
this.props.fetchRoles();
this.onSubmit = this.onSubmit.bind(this);
}
...
export const mapDispatchToProps = dispatch => {
return {
fetchRoles: () => {
dispatch(fetchRoles());
}
};
};
The Store
import {createStore, combineReducers, applyMiddleware, compose} from 'redux';
import thunk from 'redux-thunk';
import {reducer as formReducer} from 'redux-form';
// Reducers
import partyReducer from '../reducers/party-reducer';
export default function configureStore(initialState) {
let reducer = combineReducers({
form: formReducer,
party: partyReducer
});
let enhancements = [applyMiddleware(thunk)];
if (process.env.PROD_ENV !== 'production' && typeof window !== 'undefined' && window.__REDUX_DEVTOOLS_EXTENSION__) {
enhancements.push(window.__REDUX_DEVTOOLS_EXTENSION__());
}
return createStore(reducer, initialState, compose(...enhancements));
}
What I've tried
I noticed my mapDispatchToProps was written kinda strange so I fixed that, but I still get the error actions is undefined if I remove the if statement :'(
import {fetchRoles as fetchRolesAction} from '../../../actions/party-actions';
...
export const mapDispatchToProps = dispatch => ({
fetchRoles: () => dispatch(fetchRolesAction())
});
Figured it out! Was my test!
it('returns expected initState', () => {
let expected = {roles: []};
let actual = partyReducer();
expect(actual).toEqual(expected);
});
^ test above is suppose to see if the initial state is return if no state is passed in. However Actions should Always be passed in.
Fix:
it('returns expected initState', () => {
let expected = {roles: []};
let actual = partyReducer(undefined, {}); // <-- undefined state, + action
expect(actual).toEqual(expected);
});
So inside of my uncontrolled PossibleMatches component, I know from the way React works, the initial rendering phase will occur with empty prop values (if those prop values rely on external application state (mapStateToProps)) regardless of whether or not I have a componentDidMount lifecycle method or constructor setup. In response to this, I've setup a promise inside of the componentDidMount so that when I dispatch prop functions [defaultPieces, arrangePieces], I can have the UI render an ActivityIndicator to indicate something is currently fetching. The problem is, I cannot seem to get the mapStateToProps function to understand the state when I call mapStateToProps from within the success phase of the promise. Here it is:
class PossibleMatches extends Component {
constructor(props){
super(props);
}
componentDidMount(props){
return new Promise((resolve, reject) => {
let state;
let {defaultPieces, arrangePieces, isFetching} = this.props;
let makeClothesAppear = function(){
defaultPieces();
arrangePieces();
isFetching = true;
}
resolve(makeClothesAppear());
}).then(function(state){
mapStateToProps(state);
this.props.isFetched = true
this.props.isFetching = false;
}).catch((error) => {
console.log('FetchClothesError: ', error);
})
}
}
How the UI would make a decision on what to display:
renderDecision(){
const {UpperComponents, LowerComponents} = this.props;
const {currentUpperComponent, currentLowerComponent} = this.state.currentComponent.whichPiece;
const {LowerComponentEnabled, UpperComponentEnabled} = this.state;
if (this.props.isFetching){
return (<div className='activityLoader'>
<ActivityIndicator number={3} duration={200} activeColor="#fff" borderWidth={2} borderColor="50%" diameter={20}/>
</div>);
} else if (this.props.isFetched){
return (<div className = "PossibleMatches_Container">
<i className = 'captureOutfit' onClick = {this.snapshotMatch}></i>
{UpperComponents.map((component) => {
return (<UpperComponent key={component.createdAt} id={component.id}
switchComponent={this.switchFocus}
setCurrentPiece = {this.setNewPiece}
evaluatePiece={this.isOppositeComponentSuggested}
image={component.image}
toggleToPiece = {(LowerComponentEnabled) => {if (LowerComponentEnabled === false){this.setState({LowerComponentEnabled: true})}else{return;} this.setState({currentLowerComponent: this.props.suggestedBottoms[0]})}}
isLowerComponentEnabled={LowerComponentEnabled}
ref={this.residingUpperComponent}
className = {this.state.currentComponent.whichPiece.whichType === 'match' ? 'PossibleMatches_Container' : this.state.currentComponent.whichPiece.whichType === 'bottom' ? 'standalonePiece' : 'standalonePiece'}/>)
})
}
{LowerComponents.map((component) => {
return (<LowerComponent key={component.createdAt} id={component.id}
setCurrentPiece = {this.setNewPiece}
evaluatePiece={this.isOppositeComponentSuggested}
image={component.image}
toggleToPiece={(UpperComponentEnabled) => {if (UpperComponentEnabled === false){this.setState({UpperComponentEnabled: true})}else{return;} this.setState({currentUpperComponent: this.props.suggestedTops[0]})}}
switchComponent={this.switchFocus}
isUpperComponentEnabled={UpperComponentEnabled}
ref={this.residingLowerComponent}
className = {this.state.currentComponent.whichPiece.whichType === 'match' ? 'PossibleMatches_Container' : this.state.currentComponent.whichPiece.whichType === 'bottom' ? 'standalonePiece' : 'standalonePiece'}/>)
})
}
</div>)
}
}
render(){
return(
<div className = 'GorClothingContainer'>
{/*<Wardrobe upperComponent={this.state.currentComponent.whichPiece.currentUpperComponent} lowerComponent={this.state.currentComponent.whichPiece.currentLowerComponent} enableCapture={(snapshot) => this.snapshotMatch = snapshot} />*/}
{this.renderDecision()}
</div>
);
}
My PossibleMatches Reducer
import {INITIAL_PIECES, GET_ANCILLARY_PIECES, ORGANIZE_PIECES, SET_CONTEMPLATED_PIECE} from '../actions/types';
const initialState = {
UpperComponents: [],
LowerComponents: [],
contemplated_piece: null,
extraTops: [],
extraBottoms: [],
standaloneTops: [],
standaloneBottoms: [],
suggestedTops: [],
suggestedBottoms: []
}
export default function(state = initialState, action){
switch(action.type){
case INITIAL_PIECES:
return Object.assign({}, state, {contemplated_piece: action.payload.contemplated_piece},
{extraTops: action.payload.extra_tops},
{extraBottoms: action.payload.extra_bottoms},
{standaloneTops: action.payload.standalone_tops},
{standaloneBottoms: action.payload.standalone_bottoms},
{suggestedTops: action.payload.suggested_tops},
{suggestedBottoms: action.payload.suggested_bottoms})
case GET_ANCILLARY_PIECES:
return Object.assign({}, state, {extraTops: action.payload.extra_tops},
{extraBottoms: action.payload.extra_bottoms},
{standaloneTops: action.payload.standalone_tops},
{standaloneBottoms: action.payload.standalone_bottoms},
{suggestedTops: action.payload.suggested_tops},
{suggestedBottoms: action.payload.suggested_bottoms})
case ORGANIZE_PIECES:
return Object.assign({}, state, {UpperComponents: action.payload.UpperComponents},
{LowerComponents: action.payload.LowerComponents})
case SET_CONTEMPLATED_PIECE:
return Object.assign({}, state, {contemplated_piece: action.payload.contemplated_piece})
default:
return state;
}
}
My combineReducers segment
import {combineReducers} from 'redux';
const allReducers = combineReducers({
Playlist: PlaylistReducer,
eventOptions: eventTicketReducer,
possibleMatches: PossibleMatchesReducer,
Intro: combineForms({
basicUserInfo: BasicUserInfoState,
GenderInfo: GenderInfoState,
ContactInfo: ContactInfoState
}, 'Intro'),
routing: routerReducer,
form: formReducer
});
Prop Values:
PossibleMatches.defaultProps = {
isFetching: true,
isFetched: false
}
My mapStateToProps function
function mapStateToProps(state){
return {UpperComponents: state.possibleMatches.UpperComponents,
LowerComponents: state.possibleMatches.LowerComponents,
contemplatedPiece: state.possibleMatches.contemplated_piece,
extraTops: state.possibleMatches.extraTops,
extraBottoms: state.possibleMatches.extraBottoms,
standaloneTops: state.possibleMatches.standaloneTops,
standaloneBottoms: state.possibleMatches.standaloneBottoms,
suggestedTops: state.possibleMatches.suggestedTops,
suggestedBottoms: state.possibleMatches.suggestedBottoms}
}
function mapDispatchToProps(dispatch){
return {
defaultPieces: () => {
dispatch(defaultPieces())
},
arrangePieces: () => {
dispatch(arrangePieces())
},
getCorrespondingPieces: () => {
dispatch(getCorrespondingPieces())
},
setEvaluatedPiece: () => {
dispatch(setEvaluatedPiece())
}
}
}
export default connect(mapStateToProps, mapDispatchToProps)(PossibleMatches)
My Question is: What exactly is wrong with the way that I've implemented the promise. With the reducers and the redux actions setup correctly(I know because I've logged the fetched items to the console from the redux actions file), how can I properly populate the prop values in mapStateToProps. Currently the error is:
Im using React 16.4.0
A simple redux use case would seem as follows
possibleMatches.jsx (Component file)
class PossibleMatches extends React.Component {
state = {
isFetching: false
}
componentDidMount() {
this.setState({isFetching: true})
fetchingSomethingFromServer()
.then(resp => {
this.setState({isFetching: false})
this.props.UpdateRedux(resp)
});
}
render() {
const { isFetching } = this.state;
const { data } = this.props;
return (
isFetching ? <div>loading...</div> : <div>{data}</div>
)
}
}
export default connect(state => ({ data: state.possibleMatches.data }), {UpdateRedux})
actions.js (action creator file)
Use this action to update any data into redux
export const UpdateRedux = (data) => {type: 'UPDATE_REDUX', payload: data}
reducers.js
This is the file that holds the redux state
const defaultState = {
data: null
}
export default (state = defaultState, action) => {
switch(action.type) {
case 'UPDATE_REDUX':
return {data: action.payload};
default:
return state
}
}
In your combine reducers import this reducer and assign it as follows
import possibleMatches from 'reducers.js';
combineReducers({ possibleMatches });