I have a problem that a react component is rendering before the redux store has any data.
The problem is caused by the React component being rendered to the page before the existing angular app has dispatched the data to the store.
I cannot alter the order of the rendering or anything like that.
My simple React component is
import React, {Component} from 'react';
import { connect } from 'react-redux';
import {addBot} from './actions';
class FlowsContainer extends React.Component {
componentDidMount() {
this.props.initStoreWithBot();
}
render() {
// *** at this point I have the store in state prop
//but editorFlow array is not yet instanced, it's undefined
const tasks = this.props.state.editorFlow[0].flow.tasks
return (
<div>
Flow editor react component in main container
</div>
);
}
}
const mapStateToProps = (state) => ({
state : state
})
const mapDispatchToProps = (dispatch) => {
return {
initStoreWithBot : () => dispatch(addBot("test 123"))
};
};
export default connect(
mapStateToProps,
mapDispatchToProps
)(FlowsContainer)
So how can I hold off the rendering until editorFlow array has elements ?
You can use Conditional Rendering.
import {addBot} from './actions';
class FlowsContainer extends React.Component {
componentDidMount() {
this.props.initStoreWithBot();
}
render() {
// *** at this point I have the store in state prop
//but editorFlow array is not yet instanced, it's undefined
const { editorFlow } = this.props.state;
let tasks;
if (typeof editorFlow === 'object' && editorFlow.length > 0) {
tasks = editorFlow[0].flow.tasks;
}
return (
{tasks &&
<div>
Flow editor react component in main container
</div>
}
);
}
}
const mapStateToProps = (state) => ({
state : state
})
const mapDispatchToProps = (dispatch) => {
return {
initStoreWithBot : () => dispatch(addBot("test 123"))
};
};
export default connect(
mapStateToProps,
mapDispatchToProps
)(FlowsContainer)
As far as I know, you can't.
the way redux works is that it first renders everything, then actions take place with some async stuff(such as loading data), then the store gets populated, and then redux updates the components with the new state(using mapStateToProps).
the lifecycle as I understand it is this :
render the component with the initial state tree that's provided when you create the store.
Do async actions, load data, extend/modify the redux state
Redux updates your components with the new state.
I don't think mapping the entire redux state to a single prop is a good idea, the component should really take what it needs from the global state.
Adding some sane defaults to your component can ensure that a "loading" spinner is displayed until the data is fetched.
In response to Cssko (I've upped your answer) (and thedude) thanks guys a working solution is
import React, {Component} from 'react';
import { connect } from 'react-redux';
import {addBot} from './actions';
class FlowsContainer extends React.Component {
componentDidMount() {
this.props.initStoreWithBot();
}
render() {
const { editorFlow } = this.props.state;
let tasks;
if (typeof editorFlow === 'object' && editorFlow.length > 0) {
tasks = editorFlow[0].flow.tasks;
}
if(tasks){
return (
<div>
Flow editor react component in main container
</div>
)
}
else{
return null;
}
}
}
const mapStateToProps = (state) => ({
state : state
})
const mapDispatchToProps = (dispatch) => {
return {
initStoreWithBot : () => dispatch(addBot("test 123"))
};
};
export default connect(
mapStateToProps,
mapDispatchToProps
)(FlowsContainer)
Related
i have a parent component and one child component (custom function component). in my child component i have event handler that will change the state (redux) from the parent. everything work fine when i call the addProduct function the state is added i can see in my redux tools product state is changed. But Why after i added i cant access that state (console.log (product._id)) i get a error message a product is null and one thing make me confused is i can access that state in my JSX from parent Component ({JSON.stringify(product)}) but not after i added.
here is my code
import React, { Fragment } from 'react';
import { connect } from 'react-redux';
import PropTypes from 'prop-types';
import {addProduct} from '../action/product';
const ChildComponent = ({onClick}) => {
return (
<button onClick={onClick}>Add</button>
)
}
const ParentComponent = ({product}) => {
const onNotFoundThenAddNew = () => {
addProduct ({name : 'new product'});
console.log(product._id);
}
return (
<Fragment>
{JSON.stringify(product)}
<ChildComponent onClick={onNotFoundThenAddNew}/>
</Fragment>
)
}
ParentComponent.propTypes = {
addProduct : PropTypes.func,
product : PropTypes.object
};
const mapStateToProps = (state) => ({
product : state.product.product
})
export default connect (mapStateToProps, {addProduct}) (ParentComponent)
If MyComponent gets data from the redux store, but organises it in some way first before mapping it, should that organisation be done in the component or mapStateToProps function and why?
const MyComponent = ({ data }) => {
// IN HERE?
return (
<div>
{data.map((d) => (...))}
</div>
);
};
const mapStateToProps = (state) => {
const output = state.data
// OR HERE?
return { data: output };
};
export default connect(mapStateToProps)(MyComponent);
Hello have a nice day.
i think is better have a file with all the logic to conect with redux, so every time i need to connect with redux i create a file that name is ComponentNameContainer.jsx, this file looks like that:
import { connect } from 'react-redux';
import { withRouter } from 'react-router';
import Row from '../components/Row';
import {doSomething} from '../redux/somethingActions'
// here the imports of function from your actions
export default withRouter(connect(
(state, ownProps) => {
return {
// props that u need from redux
// example: state.sessionReducer.user
}
},
{
// functions that u need from redux
//example: doSomething
}
)(Row))
i have a folder call containers to store all the container files to keep track of the components that are connected with redux.
import React from "react";
import OtherComponent from "./OtherComponent";
class Main extends React.Component {
constructor(props) {
super(props);
this.runMyFunction = this.runMyFunction.bind(this);
this.myFunction = this.myFunction.bind(this);
}
runMyFunction(event) {
event.preventDefault();
this.myFunction();
}
myFunction() {
return console.log("I was executed in Main.js");
}
render() {
return (
<div>
<OtherComponent runMyFunction={this.runMyFunction} />
</div>
);
}
}
export default Main;
import React from "react";
class OtherComponent extends React.Component {
constructor(props) {
super(props);
this.handleClick = this.handleClick.bind(this);
}
handleClick() {
this.props.runMyFunction();
}
render() {
return (
<div>
<button onClick={this.handleClick} />Click me to execute function from Main </button>
</div>
);
}
}
export default OtherComponent;
I'm new in redux and don't know how to pass and run that function in other component. It was easy not using redux, just pass as props like in example above.
I have folder with actions, components, containers and reducers.
Now I have Main.js where I have
import React from "react";
const Main = ({data, getData}) => {
const myFunction = () => {
return "ok";
};
return (
<div>
<p>This is main component</p>
</div>
);
};
export default Main;
In MainContainer.js I got:
import Main from "../../components/Main/Main";
import { connect } from "react-redux";
import {
getData
} from "../../actions";
function mapStateToProps(state) {
return {
data: state.main.data
};
}
const mapDispatchToProps = (dispatch) => {
return {
getData: () => dispatch(getData())
};
};
export default connect(
mapStateToProps,
mapDispatchToProps
)(Main);
So how I can run function myFunction() in OtherComponent.js:
import React from "react";
const OtherComponent = ({executeFunctionInMainComponent}) => {
return (
<div>
<button onClick={executeFunctionInMainComponent}>run action</button>
</div>
);
};
export default OtherComponent;
I need to just run, not pass whole function, just execute myFunction in Main.js but action to run this function will came from OtherComponent.
So first i have to mention that i believe that you have a misconception of redux. This isn't to allow for functions created in components to be reused in different locations. This is to move that logic to a reducer outside of your function which would allow it to be used wherever you wired it with {connect} from react-redux. So you will need a couple of files (for clarity). First you're going to need an action file which we'll name myReturnOkAction.
export const myReturnOkAction = (/*optional payload*/) => {
return {
type: 'PRINT_OK',
}
}
Redux Actions
This is what you're going to call in your mapDispatchToProps function where you're going to trigger this event. You're going to have to import it into your OtherComponent so import {myReturnOkAction} from "/*wherever the files exists*/" and to include it in your mapDispatchToProps as okFunction: () => dispatch(myReturnOkAction())
Once you have your action your connect Higher Order Component (HOC) wrapping your main component is going to need a Reducer to modify your current store state as well as do any actions.
export const myReturnOkReducer = (state, action) => {
if(action.type === 'PRINT_OK'){
/*This is where you update your global state*/
/*i.e. return {...store, valueWanted: ok}*/
}else{
return state
}
}
Redux Reducers
So the way that this is going to move is that you're function, somewhere is going to call the action. Once the action is called its going to trigger the reducer and make any changes to the store which you need. Once the reducer has updated the store with new values its then going to update any components which are connected to it through the connect HOC which will cause them to re-render with new information.
Also my favorite image to describe how redux works.
I hope this helps.
I found an answer:
I still can pass as props in redux but I can't do this in this way: OtherComponent = ({executeFunctionInMainComponent}) => {}. I need to do in this way: OtherComponent = (props) => {} and then inside that component I have an access via props.executeFunctionInMainComponent
I'm having an issue with a React Native application that uses Redux, and I've struggling to figure out the cause.
When the Redux state is changed by a dispatch in component A, component B doesn't show the most up to date value of the Redux state. For example, say I click a button in component A to change a Redux value from 0 to 1, it will show 0 in component B, but when I click the button to add 1 to make it 2, component B will show 1. Below is an example of my code. When I click on the TouchableOpacity in component A, it should change this.props.screen from 1 (the initial state) to 0. In component B, I have a regular console.log of this.props.screen, and a console.log inside a setTimeout with 50 milliseconds. Inside the console, the console.log in the setTimeout has the correct value of 0 when hit, however the one outside it still shows 1. Similarly, the text rendered in component B will show 1 as well. If I click the button again, it will then show 0.
I've included the relevant action and reducer from my code. At first, I thought it might be a mutation, but it seemed that can only happen with objects and arrays (I'm only using a number). I would appreciate some help figuring out how to have the text rendered in component B reflect the most current value. Thanks in advance!
Component A
import { connect } from "react-redux";
import { setScreen } from "../redux/Actions";
class Header extends Component {
componentWillReceiveProps(nextProps){
setTimeout(() => { this.logoHide() },10);
this.props.scrollLocation < 10 ? this.changeTransparency(0) : this.changeTransparency(.9);
}
setScreen(screen){
this.props.setScreen(screen);
}
render() {
var {height, width} = Dimensions.get('window');
return (
<View>
<TouchableOpacity onPress={() => this.setScreen(0)}>
<Text>Click Me</Text>
</TouchableOpacity>
</View>
);
}
}
const mapStateToProps = state => {
return {
height: state.height,
platform: state.platform,
screen: state.screen,
scrollLocation: state.scrollLocation
};
};
const mapDispatchToProps = dispatch => {
return {
setScreen: (value) => dispatch(setScreen(value))
};
};
export default connect(mapStateToProps,mapDispatchToProps)(Header);
Redux Action
import { SET_SCREEN } from './Constants';
export const setScreenDispatcher = (value) => ({ type: SET_SCREEN, screen: value});
export const setScreen = (value) => {
return (dispatch) => {
dispatch(setScreenDispatcher(value));
}
}
Redux Reducer
import { combineReducers } from 'redux';
import { SET_SCREEN } from "./Constants";
const initialState = []
const screen = (state = 1, action) => {
switch (action.type) {
case SET_SCREEN:
return action.screen;
default:
return state;
}
};
// COMBINE REDUCERS //
export default combineReducers({
screen
});
Component B
import { connect } from "react-redux";
class VisibleMenus extends Component {
componentWillUpdate(){
console.log(this.props.screen);
setTimeout(() => {console.log(this.props.screen)},50);
}
}
render() {
return (
<View>
<Text>{this.props.screen}</Text>
</View>
);
}
}
const mapStateToProps = state => {
return {
screen: state.screen
};
};
const mapDispatchToProps = dispatch => {
return {
};
};
export default connect(mapStateToProps,mapDispatchToProps)(VisibleMenus);
App.js
import React, {Component} from 'react';
import { Provider } from "react-redux";
import VisibleMenus from './VisibleMenus';
import { Store } from "./redux/Store";
const store = Store();
export default class App extends Component {
render() {
return (
<Provider store={store}>
<VisibleMenus />
</Provider>
);
}
}
Store.js
// REDUX STORE //
import { createStore, applyMiddleware } from "redux";
import rootReducer from "./Reducers";
import ReduxThunk from 'redux-thunk'
export const Store = (initialState) => {
return createStore(
rootReducer,
initialState,
applyMiddleware(ReduxThunk)
);
}
For anyone who runs into this, I thought I'd share how I fixed it.
I researched mutations, and I definitely wasn't mutating the state, yet my components would not update when the Redux store changed.
I tried using both componentWillUpdate() and componentWillReceiveProps() but both didn't change anything. However, I was doing a comparison between this.props.screen and this.state.screen which ended up being my issue.
I should have been doing a comparison with nextProps.screen and this.state.screen inside a componentWillReceiveProps(nextProps) which ended up fixing everything.
I do want to thank Hashith for his help.
React and Redux experts.
I am new to React and Redux. My question is related to trigger callback (function) invocation when a Redux state is changed. I am stuck into this implementation. In my understanding, the presenter/view is updated via the props. Let me illustrate more in the following example.
<ParentComponent>
<Child1Component/>
<Child2Component/>
</ParentComponent>
class ParentComponent extends Component {
onChild1Click() {
this.props.dispatch(setTool(Tools.CHILD1TOOL))
}
render() {
return (
<div>
<Child1Component onChild1Click={this.onChild1Click.bind(this)}/>
<Child2Component/>
</div>
)
}
}
const mapStateToProps = state => {
return {state}
}
export default connect(
mapStateToProps
)(ParentComponent)
class Child1Component extends Component {
componentDidUpdate() {
// Question: How to get the Redux state here?
}
render() {
return (
<button onClick={this.props.onPencilClick}>Pencil</button>
)
}
}
Suppose a button is present in the Child1Component and a onclick is attached to such button. In my understanding of Redux, an action should be attached to this onclick and it should be dispatched. Such state will be modified in the ParentComponent and trigger props update. Afterwards, the UI/Presenter of Child1Component will be updated via props instead of any callback of Child1Component.
Is it possible to trigger a callback in Child1Component when a state is altered? The reason I need to make such implementation is that a 3rd party library is adopted. It requires to trigger callback. Actually, the onclick can trigger the function (callback) directly. However, the state cannot be maintained.
Could any expert advise it, please? Thanks a million.
P.
As I understand, this is not directly related to redux. You can use the react life cycle methods for this purpose. In your case, I think you need the componentDidUpdate or componentWillUpdate methods.
You can read more about life cycle methods here,
https://reactjs.org/docs/react-component.html
Explanation
First, make sure that you have connected the components to the Redux store using the react-redux bindings. Then, if you have correctly defined the mapStateToProps function, your child component will update whenever the state changes. Thus, whenever the component is updated, the componentWillUpdate and componentDidUpdate methods will be called.
Example in ES6 style
First, we'll bind the full redux state to the child component. Note: Generally you would not bind the full state, but only a branch of it.
import {connect} from 'react-redux';
import {bindActionCreators} from 'redux';
import ChildComponent from './ChildComponent';
function mapStateToProps(state) {
return {
// this will bind the redux state to the props of the child component
reduxState: state
};
}
function mapDispatchToProps(dispatch) {
return bindActionCreators({
// some action creators
}, dispatch);
}
export default connect(mapStateToProps, mapDispatchToProps)(ChildComponent);
Then we can access the redux state from the child component.
class ChildComponent extends React.Component {
componentWillMount(nextProps, nextState) {
// Do something here
console.log(this.props.reduxState)
// this.props.reduxState is accessible from anywhere in the component
}
render() {
return <div>{/*Some jsx here*/}</div>
}
}
I strongly recommend you to read about redux usage with react section from redux docs and about smart-dumb component separation
First off, thank you for the replies. I came up the solution eventually. Here it is.
// actions.js
export const SET_TOOL = 'SET_TOOL'
export const Tools = {
CHILD1TOOL: 'child1tool',
DEFAULT: 'default'
}
export function setTool(tool) {
return {
type: SET_TOOL,
tool
}
}
// reducers.js
import { combineReducers } from 'redux'
import { SET_TOOL, Tools } from './actions'
const { DEFAULT } = Tools
function currentTool(state = DEFAULT, action) {
switch(action.type) {
case SET_TOOL:
return action.tool
default:
return state
}
}
const myApp = combineReducers({
currentTool
})
export default myApp
// ParentComponent.jsx
import React, { Component } from 'react'
import { connect } from 'react-redux'
import { Tools, setTool } from './actions'
import Child1Component from './Child1Component.jsx'
class ParentComponent extends Component {
render() {
return (
<div>
<Child1Component onChild1Click={this.props.onChild1Click'}/>
</div>
)
}
}
const mapStatesToProps = state => {
return {state}
}
const mapDispatchToProps = dispatch => {
return {
onChild1Click: () => {
dispatch(setTool(Tools.CHIDL1TOOL))
}
}
}
export default connect(
mapStateToProps,
mapDispatchToProps
)(ParentComponent)
// Child1Component.jsx
import React, { Component } from 'react'
import { connect } from 'react-redux'
import { Tools } from './actions'
class Child1Component extends Component {
componentDidUpdate() {
if (this.props.state.currentTool === Tools.CHILD1TOOL) {
this.callbackHandleClick()
}
}
render() {
return <button onClick={this.props.onChild1Click}>Child 1 Button</button>
}
callbackHandleClick() {
/* callback implementation */
}
}
const mapStateToProps = state => {
return {state}
}
export default connect(
mapStateToProps
)(Child1Component)