I am struggling to figure out why a change to an object located in the store handled by a redux reducer is not triggering the componentDidUpdate method inside of my react component. I am using the react developer tools and can see the correct store after the state is reduced, and am also using redux logger and can see the correct after state after the reducer makes the change. But the component still never calls the update method.
action
export const GSAP_ANIMATION = 'GSAP_ANIMATION';
export const animateGsap = (key, next) => {
return {
type: GSAP_ANIMATION,
payload: {
key: key,
next: next
}
}
}
reducer
case GSAP_ANIMATION:
return Object.assign({}, state, {
...state,
gsap: {
...state.gsap,
[payload.key]: {
...state.gsap[payload.key],
next: {
...payload.next
}
}
}
});
component connection
const mapStateToProps = (state, ownProps) => {
return {
component: state.priorities.gsap[ownProps.id]
};
}
const mapDispatchToProps = (dispatch) => {
return {
addGsap: (key) => dispatch(actions.addGsap(key))
};
}
GsapComponent = connect(mapStateToProps, mapDispatchToProps)(GsapComponent);
In the GsapComponent I have the componentDidUpdate method, but this method is never called. However, I can see that the value of this.props.component should be correct when I view the component in the chrome extension.
edit
also doing { JSON.stringify(this.props.component) } correctly shows the updated prop values. Nothing in the react component update lifecycle is every triggered though.
I have also tried to use the immutibility-helper from react like so
return update(state, {
gsap: {
[payload.key]: {
$merge: { next: payload.next }
}
}
});
but it still doesn't call the lifecycle method.
GsapComponent source code.
Check this object assign documentation. Section Examples -> Warning for Deep Clone. I think that your reducer return object is === as state object so react can't detect change. Try json.parse(json.stringify) workaround or use immutable-js.
Related
I am trying to understand someone else their code but have difficulty understand the interaction between Redux and React.
On a React page, I invoke a Redux action called getSubscriptionPlan. Inside that Redux action, I see it is able to load the correct data (point 1 below). This uses a reducer, in which I can again confirm the correct data is there (point 2 below).
Then the logic returns to the React page (point 3 below). I now would expect to be able to find somewhere in the Redux store the previously mentioned data. However, I can't find that data listed anywhere... not in this.state (where I would expect it), nor in this.props. Did the reducer perhaps not update the store state...?
What am I doing wrong and how can I get the data to point 3 below?
React page:
import { connect } from "react-redux";
import { getSubscriptionPlan } from "../../../appRedux/actions/planAction";
async componentDidMount() {
let { planId } = this.state;
await this.props.getSubscriptionPlan(planId);
// 3. I can't find the data anywhere here: not inside this.state and not inside this.props.
this.setState({plan: this.state.plan});
}
componentDidUpdate(prevProps, prevState) {
if (prevProps.payment.paymentData !== this.props.payment.paymentData) {
this.setState({
checkout: this.props.payment.paymentData,
plan: this.props.payment.paymentData.plan,
});
}
}
const mapStateToProps = (state) => {
return {
plan: state.plan,
};
};
const mapDispatchToProps = (dispatch) => {
return bindActionCreators(
{ getSubscriptionPlan }, dispatch
);
};
export default withRouter(
connect(mapStateToProps, mapDispatchToProps)(Checkout)
);
Redux action:
export const getSubscriptionPlan = (id) => {
let token = getAuthToken();
return (dispatch) => {
axios
.get(`${url}/getSubscriptionPlan/${id}`, {
headers: { Authorization: `${token}` },
})
.then((res) => {
if (res.status === 200) {
// 1. From console.log(res.data) I know res.data correctly now contains the data
return dispatch({
type: GET_PLAN_SUCCESS,
payload: res.data,
});
})
};
};
Reducer:
export default function planReducer(state = initial_state, action) {
switch (action.type) {
case GET_PLAN_SUCCESS:
// 2. I know action.payload, at this point contains the correct data.
return { ...state, plan: action.payload };
default:
return state;
}
}
You are getting tripped up on how Redux works.
Redux does not use react component state. It manages state separately, and passes that state to components as props. When you call getSubscriptionPlan, you asynchronously dispatch an event to Redux, which handles the event and updates store state in the reducer. This state is the passed to the connected components mapStateToProps function, mapped to props, and then passed as props to your component. Passing new props triggers a componentDidUpdate and a rerender of the component.
A few key things here.
Redux does not interact with component state unless you explicitly set state with props passed from Redux.
Redux is asynchronous. That means that when you make a change to state via dispatch, the change is not immediately available in the component, but only available when new props are passed. It's event driven, not data binding. As a result, in your code you woun't see the plan prop in componentDidMount because at the time componentDidMount the call to getSubscriptionPlan hasn't happened.
You should see the prop populated in this.props in componentDidUpdate and in render before the didUpdate.
When working with react, it's best to think of components as basically functions of props with some extra lifecycle methods attached.
I am new in react js. I have started doing a small product with react-redux. I am using saga middle-ware.
What i have done is as under.
This is the component
//all import work
import { activateAuthLayout, onLoad } from '../../../store/actions';
class EcommerceProductEdit extends Component {
constructor(props) {
super(props);
this.state = {
checked: false,
unselected_lists: [],
main_checked: false
}
//here I get the products props always null
console.log(this.props);
}
componentDidMount() {
this.props.activateAuthLayout();
//dispatching an action to fetch data from api, done in midddleware
if (this.props.user !== null && this.props.user.shop_id)
this.props.onLoad({
payload: this.props.user
});
}
render() {
//here I get the products props
console.log(this.props);
return (
//jsx work
);
}
}
const mapStatetoProps = state => {
const { user, is_logged_in } = state.Common;
const { products, is_loading } = state.Products;
return { user, is_logged_in, products, is_loading };
}
export default withRouter(connect(mapStatetoProps, { activateAuthLayout, onLoad })(EcommerceProductEdit));
Action is
import { FETCH_PRODUCT, FETCH_PRODUCT_SUCCESS } from './actionTypes';
export const onLoad = (action) => {
return {
type: FETCH_PRODUCT,
payload: action.payload
}
}
export const productFetched = (action) => {
return {
type: FETCH_PRODUCT_SUCCESS,
payload: action.payload
}
}
Reducer is
import { FETCH_PRODUCT_SUCCESS } from './actionTypes';
const initialState = {
products: null,
is_loading: true
}
export default (state = initialState, action) => {
switch (action.type) {
case FETCH_PRODUCT_SUCCESS:
state = {
...state,
products: action.payload,
is_loading: false
}
break;
default:
state = { ...state };
break;
}
return state;
}
And saga is
import { takeEvery, put, call } from 'redux-saga/effects';
import { FETCH_PRODUCT } from './actionTypes';
import { productFetched } from './actions';
import agent from '../../agent';
function* fetchProduct(action) {
try {
let response = yield call(agent.Products.get, action.payload);
yield put(productFetched({ payload: response }));
} catch (error) {
if (error.message) {
console.log(error);
} else if (error.response.text === 'Unauthorized') {
console.log(error)
}
}
}
function* productSaga() {
yield takeEvery(FETCH_PRODUCT, fetchProduct)
}
export default productSaga;
I am being able to get the products props only in render function. How would i be able to get it it in constructor ?
I would be really grateful if anyone explained me about react life cycle a little bit more.
Thanks.
updated
a constructor is called during object instantiation. According to the docs "The constructor for a React component is called before it is mounted". So if the props passed to the component are being changed after the component has been mounted you can use componentWillReceiveProps life cycle methods.
componentWillReceiveProps is deprecated so you can use componentDidUpdate instead. Example from the docs.
componentDidUpdate(prevProps) {
// Typical usage (don't forget to compare props):
if (this.props.userID !== prevProps.userID) {
// update your component state from here.
this.fetchData(this.props.userID);
}
}
MiddleWare: Middleware just comes in between the flow after the action has been dispatched and before it reaches the reducers, like in your case once you fire onLoad action and before it reaches the reducers, its caught in Saga middleware which executes it according to code written in it
Lifecycle in your case goes the following way:
In your compoenentDidMount method, you dispatch an action of onLoad. The action type in such a case becomes "FETCH_PRODUCT" and same action is now caught in Saga.
Since this is async call, the code in your component continues executing while the Saga perform its action in parallel. It calls API through this line of code: yield call(agent.Products.get, action.payload); . Once API call is completed, it dispatches an action 'productfetched' through this line of code yield put(productFetched({ payload: response }));.
Now this action reaches reducer and modify the state of "products". Since the product state in your redux is modified, your component EcommerceProductEdit re-renders and you get your product list in render method. The point to be noted is that the flow must have already finished executing inside componentDidMount method by this time, so no chance of having products their
Solution to your problem:
Once an action is dispatched and which has become async due to Saga, you won't be able to get value in constructor, if you use Saga. You can just directly call upon the API using axios/fetch library in componentDidMount and await their (Making it synchronous). Once you get response, you may proceed further
In case you have functional component, then you may use Effect hook and bind the dependency to products state. You can write your code in this block, what you want to be executed after API call is made and product list modifies.
React.useEffect(
() => {
// You code goes here
},
[products]
);
You just have to console props rather than doing this.props. You should not reference props with this inside the constructor.
Do this instead:
console.log(props)
Middleware is not related to react lifecycle at all, other than it updates and connected components "react" to props updating.
Check the constructor docs
https://reactjs.org/docs/react-component.html#constructor
Question: why are you trying to log props in the constructor anyway? If you want to know what the props are, use one of the lifecycle functions, componentDidMount/componentDidUpdate, don't use the render function to do side-effects like make asynchronous calls or console log.
componentDidMount() {
console.log(this.props);
}
If you must log props in the constructor though, access the props object that was passed as the component won't have a this.props populated yet.
constructor(props) {
super(props);
...
console.log(props);
}
In my react app I have component named profile, and I am fetching data from server and showing it inside that component. I am using redux and redux-thunk along with axios. With help of mapDispatchToProps function, i am calling redux action for fetching that data when component is mounted and saving it to redux state. After that, using mapStateToProps function i am showing that data on the screen via props. That works fine. Now I want to have possibility to edit, for example, first name of that user. To accomplish that i need to save that data to component state when data is fetched from server, and then when text field is changed, component state also needs to be changed. Don't know how to save data to component sate, immediately after it is fetched.
Simplified code:
const mapStateToProps = (state) => {
return {
user: state.user
}
}
const mapDispatchToProps = (dispatch) => {
return {
getUserData: () => dispatch(userActions.getUserData())
}
}
class Profile extends Component {
state:{
user: {}
}
componentDidMount (){
this.props.getUserData()
// when data is saved to redux state i need to save it to component state
}
editTextField = () => {
this.setState({
[e.target.id]: e.target.value
})
};
render(){
const { user } = this.props;
return(
<TextField id="firstName"
value={user.firstName}
onChange={this.editTextField}
/>
)
}
}
You can use componentDidUpdate for that or give a callback function to your action.
I will show both.
First lets see componentDidUpdate,
Here you can compare your previous data and your present data, and if there is some change, you can set your state, for example if you data is an array.
state = {
data: []
}
then inside your componentDidUpdate
componentDidUpdate(prevProps, prevState) {
if(prevProps.data.length !== this.props.data.length) {
// update your state, in your case you just need userData, so you
// can compare something like name or something else, but still
// for better equality check, you can use lodash, it will also check for objects,
this.setState({ data: this.props.data});
}
}
_.isEqual(a, b); // returns false if different
This was one solution, another solution is to pass a call back funtion to your action,
lets say you call this.props.getData()
you can do something like this
this.props.getData((data) => {
this.setState({ data });
})
here you pass your data from redux action to your state.
your redux action would be something like this.
export const getData = (done) => async dispatch => {
const data = await getSomeData(); // or api call
// when you dispatch your action, also call your done
done(data);
}
If you are using React 16.0+, you can use the static method getDerivedStateFromProps. You can read about it react docs.
Using your example:
class Profile extends Component {
// other methods here ...
static getDerivedStateFromProps(props) {
return {
user: props.user
}
}
// other methods here...
}
In my react application, I have three parallel components. In my first component, I am doing an API call and based on the response I am routing the flow to Validated or Non-Validated Component.
Once the user is routed to validated component, there is a button on click of which user should be redirected to another component which should display the data in API response (first component) as key value pair. I am using Redux for state management.
The issue I am facing is the data is dispatched as an empty object from the store. I am not sure where I am going wrong but when I am debugging the app, I see the the action is not getting dispatched to the store and it's always returning me the initial state.
action.js-
export const setPoiData = (poiData) => dispatch => {
console.log('inside actions');
dispatch({
type: SET_POI_DATA,
payload: poiData
})
}
Reducer.js-
const initialState = {
poiData: {},
}
const reducerFunc = (state = initialState, action) => {
switch (action.type) {
case SET_POI_DATA:
console.log('inside poi reducers');
return {...state,poiData: action.payload}
default: return {...state}
}
}
Component 1-
//API call
Detail Component-
To get the data from store I am doing something like below-
componentDidMount() {
console.log(this.props.poiData)
}
function mapStateToProps(state) {
return {
poiData: state.poiData,
}
}
const mapDispatchToProps = dispatch => ({
setPoiData(data) {
dispatch(setPoiData(data));
}
})
I am not sure where I am going wrong. Can someone suggest me how to proceed ahead on this?
inside componentDidMount() you must call action like this this.props.setPoiData(<your data here>);
I am setting my redux state through a value I have in localStorage. This works fine when I navigate into my page. However, when I do a hard refresh the state is never set, despite the value in localStorage being passed down.
This is what my code looks like:
class SomeComponent {
componentWillMount() {
if (typeof localStorage !== 'undefined') {
console.log('I get to here...', localStorage.getItem('someValue')) // this comes in as expected always
this.props.setMyReduxState(localStorage.getItem('someValue'))
}
}
render () {
// will have the value of the localStorage item someValue when navigated into the page
// will be an empty string if I do a hard refresh
console.log('this.props.myReduxState', this.props.myReduxState)
return (
<div>
Stuff...
</div>
)
}
}
const mapStateToProps = (state) => {
return {
myReduxState: state.something.myReduxState || ''
}
}
const mapDispatchToProps = (dispatch) => {
return {
setMyReduxState (someValue) {
dispatch(setMyReduxState(someValue))
}
}
}
Any ideas?
Edit: just a small addition to simplify the problem: I also tried it sending a string directly to setMyReduxState function, without the localStorage, the state still isn't being set. So basically something like this:
componentWillMount() {
this.props.setMyReduxState('some string!')
}
From my understanding every time the redux state is set, the component should re-draw, which isn't happening when there is a hard refresh. Are there any reasons for this or something being done incorrectly?
Edit2: Including my action creator and reducer in case needed:
const SET_MY_REDUX_STRING = 'admin/users/SET_MY_REDUX_STRING'
const defaultState = {
myReduxState: ''
}
export function setMyReduxState (value) {
return {
type: SET_MY_REDUX_STRING,
myReduxState: value
}
}
export default function reducer (state = defaultState, action = {}) {
switch (action.type) {
case SET_MY_REDUX_STRING:
return Object.assign({}, state, { myReduxState: action.myReduxState })
default:
return state
}
}
Some of the checklist you need to follow while using redux -
Are you dispatching an action creator that returns an object with 'type' and data? Here 'type' is mandatory.
Does your reducer return the state with the updated data that it received?
Make sure you do not mutate the state in reducer. Always use {...state, someKey: someValue}