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Child component doesn't rerender but parent component does rerender. How to make child component rerender?

Parent component does rerender upon receiving new props but its child component doesn't rerender. Child components only render for the first time and never rerender nor receive props from the redux store
I'm getting updated data from redux store in Parent component but not in the child components. Child components only receive data from redux store when they render for the first time
My Parent Component Home.js
Object seaFCLJSON look like this
const seaFCLJSON ={"rates": {"sort":"faster", "someOther": "someOtherValues"}};
when the redux store gets updated, seaFCLJSON looks like this
const seaFCLJSON ={"rates": {"sort":"cheaper","someOther": "someOtherValues"}};
class Home extends Component {
state = {
seaFCLJSON: {}
};
componentDidMount = () => {
this.setState({ seaFCLJSON: this.props.seaFCLJSON });
};
componentWillReceiveProps = nextProps => {
if (this.state.seaFCLJSON !== nextProps.seaFCLJSON) {
this.setState({ seaFCLJSON: nextProps.seaFCLJSON });
}
};
render() {
const { seaFCLJSON } = this.props;
return (
<>
{!isEmpty(seaFCLJSON) && seaFCLJSON.rates && seaFCLJSON.rates.fcl ? (
<FCLContainer fclJSON={seaFCLJSON} />
) : null} //it never rerenders upon getting updated data from redux store
<h5>{JSON.stringify(seaFCLJSON.rates && seaFCLJSON.rates.sort)}</h5> //it rerenders everytime upon getting updated data from redux store
</>
);
}
}
const mapStateToProps = state => {
return {
seaFCLJSON: state.route.seaFCLJSON
};
};
export default connect(
mapStateToProps,
actions
)(Home);
isEmpty.js
export const isEmpty = obj => {
return Object.entries(obj).length === 0 && obj.constructor === Object;
};
My Child Component FCLContainer.js
class FCLContainer extends Component {
state = {
seaFCLJSON: {}
};
componentDidMount = () => {
this.setState({ seaFCLJSON: this.props.seaFCLJSON });
};
componentWillReceiveProps = nextProps => {
console.log("outside state value: ", this.state.seaFCLJSON);
if (this.state.seaFCLJSON !== nextProps.seaFCLJSON) {
this.setState({ seaFCLJSON: nextProps.seaFCLJSON });
console.log("inside state value: ", this.state.seaFCLJSON);
}
};
render() {
const { seaFCLJSON } = this.state;
console.log("rendering .. parent props: ", this.props.fclJSON);
console.log("rendering .. redux store props: ", this.props.seaFCLJSON);
return (
<>
<div className="home-result-container">
<div>
<h5>This child component never rerenders :(</h5>
</div>
</div>
</>
);
}
}
const mapStateToProps = state => {
return {
seaFCLJSON: state.route.seaFCLJSON
};
};
export default connect(
mapStateToProps,
actions
)(FCLContainer);
I don't know whether there are problems in Parent component or problems in the child component. componentWillReceiveProps gets invoked in the parent component but not in the child component. Please ignore any missing semi-colon or braces because I have omitted some unnecessary codes.
Edit 1: I just duplicated value from props to state just for debugging purposes.
I will appreciate your help. Thank you.
Edit 2: I was directly changing an object in redux actions. That's the reason CWRP was not getting fired. It was the problem. For more check out my answer below.

componentWillReceiveProps will be deprecated in react 17, use componentDidUpdate instead, which is invoked immediately after updating occurs
Try something like this:
componentDidUpdate(prevProps, prevState) {
if (this.prevProps.seaFCLJSON !== this.props.seaFCLJSON) {
this.setState({ seaFCLJSON: this.props.seaFCLJSON });
}
};

At the first place it is absolutely meaningless to duplicate value from props to state, what is the meaning of it? Totally pointless, just keep it in props
About your issue - most probably this condition doesnt match, thats why child component doesnt trigger
!isEmpty(seaFCLJSON) && seaFCLJSON.rates && seaFCLJSON.rates.fcl
check it in debugger

As far as I can see, your problem is that you pass the following to your child component:
<FCLContainer fclJSON={seaFCLJSON} />
But you assume that you receive a prop called 'seaFCLJSON':
componentDidMount = () => {
this.setState({ seaFCLJSON: this.props.seaFCLJSON });
};
You should change your code to:
<FCLContainer seaFCLJSON={seaFCLJSON} />
Apart from that, as #Paul McLoughlin already mentioned, you should use the prop directly instead of adding it to your state.

I found the issue I was directly mutating the object in actions. I only knew state should not be directly mutated in class or inside reducer. I changed the actions where I was directly changing an object and then saving it in redux store via dispatch and, then I received the updated props in CWRP. This really took me a lot of times to figure out. This kind of issue is hard to find out at least for me. I guess I get this from https://github.com/uberVU/react-guide/issues/17
A lesson I learned: Never directly mutate an Object
I changed this
//FCL sort by faster
export const sortByFasterFCLJSON = () => async (dispatch, getState) => {
let seaFCLJSON = getState().route.seaFCLJSON;
if (!seaFCLJSON.rates) return;
seaFCLJSON.rates.fcl = _.orderBy(
seaFCLJSON.rates.fcl,
["transit_time"],
["asc"]
);
seaFCLJSON.rates.sort = "Faster"; //this is the main culprit
dispatch({ type: SET_SEA_FCL_JSON, payload: seaFCLJSON });
};
to this
//FCL sort by faster
export const sortByFasterFCLJSON = () => async (dispatch, getState) => {
let seaFCLJSON = getState().route.seaFCLJSON;
if (!seaFCLJSON.rates) return;
seaFCLJSON.rates.fcl = _.orderBy(
seaFCLJSON.rates.fcl,
["transit_time"],
["asc"]
);
// seaFCLJSON.rates.sort = "Faster"; //this was the main culprit, got lost
seaFCLJSON = {
...seaFCLJSON,
rates: { ...seaFCLJSON.rates, sort: "Faster" }
};
dispatch({ type: SET_SEA_FCL_JSON, payload: seaFCLJSON });
};
the power of not mutating data
Side note: Redux Troubleshooting

Access vue method within vuex mapState

I have an important task to do while data is computed within a vuex mapState. I need to call this vue method countAlerts every time data is changed; to do that the computed property needs to call that method but this scope has no vue methods when it is used insight vuex mapState.
export default {
name: "Alerts",
methods: {
countAlerts(data, period) {
/// DO SOMETHING, THEN RETURN DATA
return data;
}
},
computed: {
...mapState({
foundation: state => state.insights.foundation,
insights: state => {
return state.insights.list.filter(al => {
switch (state.insights.foundation.period) {
case "daily":
// ====>> NEED TO CALL METHOD HERE <<=====
al = this.countAlerts(al, "daily");
if (
al.threeDayUp ||
al.threeDayDown ||
al.greatDayUp ||
al.greatDayDown
) {
return al;
}
break;
/// MORE CODE ABOVE
}
});
}
})
}
};

this is bound to the component's contex when you define computed props as functions.
From the docs:
// to access local state with `this`, a normal function must be used
countPlusLocalState (state) {
return state.count + this.localCount
}

ReactJS calling function twice inside child component fails to set parent state twice

I'm having an issue where I want to save the data from a particular fieldset with the default values on componentDidMount().
The data saving happens in the parent component, after it is sent up from the child component. However, as React's setState() is asynchronous, it is only saving data from one of the fields. I have outlined a skeleton version of my problem below. Any ideas how I can fix this?
// Parent Component
class Form extends Component {
super(props);
this.manageData = this.manageData.bind(this);
this.state = {
formData: {}
}
}
manageData(data) {
var newObj = {
[data.name]: data.value
}
var currentState = this.state.formData;
var newState = Object.assign({}, currentState, newObj);
this.setState({
formData: newState, // This only sets ONE of the fields from ChildComponent because React delays the setting of state.
)};
render() {
return (
<ChildComponent formValidate={this.manageData} />
)
}
// Child Component
class ChildComponent extends Component {
componentDidMount() {
const fieldA = {
name: 'Phone Number',
value: '123456678'
},
fieldB = {
name: 'Email Address',
value: 'john#example.com'
}
this.props.formValidate(fieldA);
this.props.formValidate(fieldB)
}
render() {
/// Things happen here.
}
}

You're already answering you're own question. React handles state asynchronously and as such you need to make sure you use the current component's state when setState is invoked. Thankfully the team behind React is well-aware of this and have provided an overload for the setState method. I would modify your manageData call to the following:
manageData(data) {
this.setState(prevState => {
const nextState = Object.assign({}, prevState);
nextState.formData[data.name] = data.value;
return nextState;
});
}
This overload for the setState takes a function whose first parameter is the component's current state at the time that the setState method is invoked. Here is the link where they begin discussing this form of the setState method.
https://reactjs.org/docs/state-and-lifecycle.html#state-updates-may-be-asynchronous

Change manageData to this
manageData(data) {
const newObj = {
[data.name]: data.value
};
this.setState(prevState => ({
formData: {
...prevState.formData,
...newObj
}
}));
}

React setState re-render

First of all, I'm really new into React, so forgive my lack of knowledge about the subject.
As far as I know, when you setState a new value, it renders again the view (or parts of it that needs re-render).
I've got something like this, and I would like to know if it's a good practice or not, how could I solve this kind of issues to improve, etc.
class MyComponent extends Component {
constructor(props) {
super(props)
this.state = {
key: value
}
this.functionRender = this.functionRender.bind(this)
this.changeValue = this.changeValue.bind(this)
}
functionRender = () => {
if(someParams !== null) {
return <AnotherComponent param={this.state.key} />
}
else {
return "<span>Loading</span>"
}
}
changeValue = (newValue) => {
this.setState({
key: newValue
})
}
render() {
return (<div>... {this.functionRender()} ... <span onClick={() => this.changeValue(otherValue)}>Click me</span></div>)
}
}
Another component
class AnotherComponent extends Component {
constructor (props) {
super(props)
}
render () {
return (
if (this.props.param === someOptions) {
return <div>Options 1</div>
} else {
return <div>Options 2</div>
}
)
}
}
The intention of the code is that when I click on the span it will change the key of the state, and then the component <AnotherComponent /> should change because of its parameter.
I assured that when I make the setState, on the callback I throw a console log with the new value, and it's setted correctly, but the AnotherComponent doesn't updates, because depending on the param given it shows one thing or another.
Maybe I need to use some lifecycle of the MyComponent?
Edit
I found that the param that AnotherComponent is receiving it does not changes, it's always the same one.

I would suggest that you'll first test it in the parent using a simple console.log on your changeValue function:
changeValue = (newValue) => {
console.log('newValue before', newValue);
this.setState({
key: newValue
}, ()=> console.log('newValue after', this.state.key))
}
setState can accept a callback that will be invoked after the state actually changed (remember that setState is async).
Since we can't see the entire component it's hard to understand what actually goes on there.
I suspect that the newValue parameter is always the same but i can't be sure.
It seems like you're missing the props in AnotherComponent's constructor. it should be:
constructor (props) {
super(props) // here
}
Try replacing the if statement with:
{this.props.param === someOptions? <div>Options 1</div>: <div>Options 2</div>}
also add this function to see if the new props actually get to the component:
componentWillReceiveProps(newProps){
console.log(newProps);
}
and check for the type of param and someOptions since you're (rightfully) using the === comparison.

First, fat arrow ( => ) autobind methods so you do not need to bind it in the constructor, second re-renders occur if you change the key of the component.
Ref: https://reactjs.org/docs/lists-and-keys.html#keys

ReactJS: How to get state value into container?

I need to get data from DB depending on a search string value. Therefore I'm using an input field. The search string is stored as a state value.
The data for the component comes from a container (using npm meteor/react-meteor-data).
Now my problem is, how do I get the search string into the container to set the parameter for the publication?
container/example.js
export default createContainer((prop) => {
Meteor.subscribe('images', searchString) // How to get searchString?
return { files: Images.find({}).fetch() }
}, Example)
component/example.jsx
class Example extends Component {
constructor(props) {
super(props)
this.state = {
searchString: ''
}
}
searchImage(event) {
const searchString = event.target.value
this.setState({ searchString })
}
render() {
return (<Input onChange={ this.searchImage.bind(this) }/>)
}
}
export default Example
publication
Meteor.publish('images', function(search) {
return Images.find({ title: search }).cursor
})

Maybe you can create two different components: a parent and a child, and you can wrap child component with createContainer HOC like the following
childComponent.js
const Example = (props) => {
return <Input onChange={props.searchImage}/>
}
export default createContainer(({searchString}) => {
Meteor.subscribe('images', searchString)
return { files: Images.find({}).fetch() }
}, Example)
parentComponent.js
class ExampleWrapper extends Component {
constructor(props) {
super(props)
this.state = {
searchString: ''
}
}
searchImage = (event) => {
const searchString = event.target.value
this.setState({ searchString })
} // instead of binding this, you can also use arrow function that
// takes care of binding
render() {
return (<Example searchImage={this.searchImage} searchString={this.state.searchString} {...this.props} />)
}
}
export default ExampleWrapper
The idea is, since createContainer is a higher order component, it doesn't have access to the props of any component wrapped by it.
What we need to do is, passing the value of searchString from a parent component.
The way to do is the following:
ExampleWrapper has a state called searchString and Example component has a prop called searchString. We can set the value of searchString prop to state.searchString.
Since the default export corresponds to createContainer({..some logic…}, Example}), createContainer can make use of prop called searchString.
In order to change the value of state.searchString we also passed searchImage function as a prop to Example component. Whenever there is a change event, onChange triggers searchImage function that updates the value of state.searchString. And eventually, the minute the value of state.searchString changes searchString prop’s value changes thus your subscription result also changes

onChange={ (e)=> {this.setState({ searchString: $(e.target).val() }) } }
This is how we assign values to our internal state properties :)
EDIT: I appear to have misunderstood the question...