I thought I got my head around closures in hooks. However, I'm struggling with this one. The code below is a very simplified version of my actual code for demonstration. In reality, clickHandler() and upload() are far more complex. That's why it's not an option to combine them into one function. The issue is that I can't access the updated files array from the state in the upload function. If I use a ref for the array it works, however, I think it's an antipattern. I also tried to declare the state outside the component, which didn't work. Thanks for your help.
import React, { useCallback, useState } from 'react';
const HomeScreen = () => {
const initialState = {
error: false,
files: [],
totalSize: 0,
finished: false
};
const [state, setState] = useState(initialState);
const upload = useCallback(() => {
// At this point state.files is an empty array
console.log(state.files);
}, [state]);
const clickHandler = useCallback(() => {
const queue = [
{ id: 1, bool: false },
{ id: 2, bool: false }
];
setState((state) => {
return { ...state, files: queue }
});
upload()
}, [upload]);
return <button onClick={clickHandler}>Click me</button>;
};
export default HomeScreen;
state updates using hooks state updater is asynchronous and hence when you call upload from within clickHandler the updated state isn't available to you. The simplest solution to pass the state to the upload method
import React, { useCallback, useState } from 'react';
const HomeScreen = () => {
const initialState = {
error: false,
files: [],
totalSize: 0,
finished: false
};
const [state, setState] = useState(initialState);
const upload = useCallback((updatedState) => {
// At this point state.files is an empty array
console.log((updatedState || state).files);
}, [state]);
const clickHandler = useCallback(() => {
const queue = [
{ id: 1, bool: false },
{ id: 2, bool: false }
];
setState((state) => {
const updatedState = { ...state, files: queue }
upload(updatedState )
return updatedState;
});
upload()
}, [upload]);
return <button onClick={clickHandler}>Click me</button>;
};
export default HomeScreen;
For your upload() function to have access to the current state it must be called from a useEffect(). See if that works for you?
const HomeScreen = () => {
const initialState = {
error: false,
files: [],
totalSize: 0,
finished: false
};
const [state, setState] = React.useState(initialState);
const upload = React.useCallback(() => {
// At this point state.files is an empty array
console.log(state.files);
}, [state]);
React.useEffect(()=>{
state.files.length ? upload() : null;
},[state]);
const clickHandler = React.useCallback(() => {
const queue = [
{ id: 1, bool: false },
{ id: 2, bool: false }
];
setState((state) => {
return { ...state, files: queue }
});
//upload()
}, [upload]);
return <button onClick={clickHandler}>Click me</button>;
};
ReactDOM.render(<HomeScreen/>, document.getElementById('root'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.3/umd/react-dom.production.min.js"></script>
<div id="root"></div>
Related
I'm having a React Error #31 which describes as "Objects are not valid as a React child."
The problem is I'm trying to do Object Destructuring for Form Validations as follows, so I'm trying to figure out the best way to solve this (unless refactoring everything to arrays?).
import { useReducer } from 'react';
const initialInputState = {
value: '',
isTouched: false,
};
const inputStateReducer = (state, action) => {
if (action.type === 'INPUT') {
return { value: action.value, isTouched: state.isTouched };
}
if (action.type === 'BLUR') {
return { isTouched: true, value: state.value };
}
if (action.type === 'RESET') {
return { isTouched: false, value: '' };
}
return inputStateReducer;
};
const useInput = (validateValue) => {
const [inputState, dispatch] = useReducer(inputStateReducer, initialInputState);
const valueIsValid = true;
const hasError = !valueIsValid && inputState.isTouched;
const valueChangeHandler = (event) => {
dispatch({ type: 'INPUT', value: event.target.value });
}
const inputBlurHandler = (event) => {
dispatch({ type: 'BLUR' });
}
const reset = () => {
dispatch({ type: 'RESET' });
}
return {
value: inputState.value,
isValid: valueIsValid,
hasError,
valueChangeHandler,
inputBlurHandler,
reset,
}
}
export default useInput;
import useInput from "../hooks/use-input";
import { useState } from 'react';
export default function InterestForms({ photoSet, onInterestLightboxChange, interestLightboxContent }) {
const alphabetOnly = (value) => /^[a-zA-Z() ]+$/.test(value);
const [isFormSubmitted, setFormSubmitted] = useState(false);
// Calling useInput and expect values in object destructuring.
// However, it seems this is causing React Error #31 since it expect values to be in different format
const {
value: nameValue,
isValid: nameIsValid,
hasError: nameHasError,
valueChangeHandler: nameChangeHandler,
inputBlurHandler: nameBlurHandler,
reset: resetName,
} = useInput(alphabetOnly);
...
Refactoring this to arrays might solve the problem. But I want to see if there's a better solution (or if I just missed something simple).
I have a form component, and the reference of input fields are linked to the useForm reducer with references. I have to set a initial form state after setting the input field references? I have done as below. But it is rendering thrice. How to solve this rendering issue?
import React, { useState } from 'react';
const useForm = () => {
const [ formState, setFormState ] = useState({});
const refs = useRef({});
const register = useCallback(( fieldArgs ) => ref => {
if(fieldArgs) {
const { name, validations, initialValue } = fieldArgs;
refs.current[name] = ref;
}
console.log('Register rendered');
}, []);
useEffect(() => {
console.log('Effect Rendered');
const refsKeys = Object.keys(refs.current);
refsKeys.forEach(refKey => {
if(!formState[refKey]) {
setFormState(prevState => {
return {
...prevState,
[refKey]: {
value: '',
touched: false,
untouched: true,
pristine: true,
dirty: false
}
}
});
}
});
}, [ refs ]);
return [ register ];
}
export { useForm };
And the app component as below
const App = () => {
const [ register ] = useFormsio();
return(
<form>
<input
type = 'email'
placeholder = 'Enter your email'
name = 'userEmail'
ref = { register({ name: 'userEmail' }) } />
<button
type = 'submit'>
Submit
</button>
</form>
)
}
How to solve this multiple rendering issue?
I think the issue in the code above is whenever refs changes you need to loop through all the fields in form and set the state.
Why don't you set the state in register method?
const register = useCallback(( fieldArgs ) => ref => {
if(fieldArgs) {
const { name, validations, initialValue } = fieldArgs;
if(!refs.current[name] ) {
refs.current[name] = ref;
setFormState(prevState => {
return {
...prevState,
[refKey]: {
value: '',
touched: false,
untouched: true,
pristine: true,
dirty: false
}
}
});
}
}
console.log('Register rendered');
}, []);
React/Redux application goes into an infinite loop on using useEffect with object references..
I am trying render pending todos for my application using useEffect.. and passing the array of todos as the second param in useEffect ..but why is not checking the values of the object ?
Container:
const mapDispatchToProps = dispatch => ({ actions: bindActionCreators(RootActions, dispatch) });
const Home = (props) => {
const { root, actions } = props;
useEffect(() => {
getTodos(actions.loadPendingTodo);
}, [root.data]);
return (
<Segment>
<Error {...root } />
<TodoList { ...root } actions={actions} />
</Segment>
);
};
export default connect(mapStateToProps, mapDispatchToProps)(Home);
Action:
export const loadPendingTodo = () => ({
type: LOAD_PENDING_TODO,
data: todoService.loadPendingTodo(),
});
Reducer:
const initialState = {
initial: true,
data: [{
id: 0,
text: 'temp todo',
dueDate: new Date(),
completedDate: '',
isDeleted: false,
isCompleted: false,
}],
error: false,
isLoading: false,
isEdit: false,
};
export default function root(state = initialState, action) {
switch (action.type) {
case LOAD_PENDING_TODO:
return {
...state,
data: [...action.data],
};
...
default:
return state;
}
}
getTodos Method:
export const getTodos = (loadTodo) => {
try {
loadTodo();
} catch (error) {
console.log(error); // eslint-disable-line
}
};
Service:
export default class TodoAppService {
loadPendingTodo() {
return store.get('todoApp').data.filter(todo => !todo.isCompleted && !todo.isDeleted);
}
Can anyone please help me out how to resolve this issue.. and there is no official documentation for this case too :/
Moreover changing the useEffect to the following works but i want to render on every change
useEffect(() => {
getTodos(actions.loadPendingTodo);
}, []);
Fixed it by removing the loadPedningTodo redux actions in useEffect that was causing it to loop and directly setting the data in function from service..
const Home = (props) => {
const { root, actions } = props;
return (
<Segment>
<Error {...root } />
<TodoList isEdit={root.isEdit} todo={todoService.loadPendingTodo()} actions={actions} />
</Segment>
);
};
thanks :)
I got one container connected to one component. Its a select-suggestion component. The problem is that both my container and component are getting too much repeated logic and i want to solve this maybe creating a configuration file or receiving from props one config.
This is the code:
import { connect } from 'react-redux';
import { withRouter } from 'react-router-dom';
import { goToPageRequest as goToPageRequestCompetitions } from '../ducks/competitions/index';
import { getSearchParam as getSearchCompetitionsParam, getCompetitionsList } from '../ducks/competitions/selectors';
import { goToPageRequest as goToPageRequestIntermediaries } from '../ducks/intermediaries/index';
import { getSearchParam as getSearchIntermediariesParam, getIntermediariesList } from '../ducks/intermediaries/selectors';
import SelectBox2 from '../components/SelectBox2';
export const COMPETITIONS_CONFIGURATION = {
goToPageRequest: goToPageRequestCompetitions(),
getSearchParam: getSearchCompetitionsParam(),
suggestions: getCompetitionsList()
};
export const INTERMEDIARIES_CONFIGURATION = {
goToPageRequest: goToPageRequestIntermediaries(),
getSearchParam: getSearchIntermediariesParam(),
suggestions: getIntermediariesList()
};
const mapStateToProps = (state, ownProps) => ({
searchString: ownProps.reduxConfiguration.getSearchParam(state),
});
const mapDispatchToProps = (dispatch, ownProps) => ({
dispatchGoToPage: goToPageRequestObj =>
dispatch(ownProps.reduxConfiguration.goToPageRequest(goToPageRequestObj)),
});
const mergeProps = (stateProps, dispatchProps, ownProps) => ({
...ownProps,
search: searchParam => dispatchProps.dispatchGoToPage({
searchParam
}),
...stateProps
});
export default withRouter(connect(mapStateToProps, mapDispatchToProps, mergeProps)(SelectBox2));
import React, { Component } from 'react';
import PropTypes from 'prop-types';
import { Flex, Box } from 'reflexbox';
import classname from 'classnames';
import styles from './index.scss';
import Input from '../Input';
import { AppButtonRoundSquareGray } from '../AppButton';
import RemovableList from '../RemovableList';
const MIN_VALUE_TO_SEARCH = 5;
const NO_SUGGESTIONS_RESULTS = 'No results found';
class SelectBox extends Component {
/**
* Component setup
* -------------------------------------------------------------------------*/
constructor(props) {
super(props);
this.state = {
displayBox: false,
selection: null,
value: '',
items: [],
suggestions: [],
};
}
/**
* Component lifecycle
* -------------------------------------------------------------------------*/
componentWillMount() {
console.log(this.props);
document.addEventListener('mousedown', this.onClickOutside, false);
if (this.props.suggestionsType){
if (this.props.suggestionsType === 'competition'){
this.state.suggestions = this.props.competitionsSuggestions;
}
if (this.props.suggestionsType === 'intermediaries'){
this.state.suggestions = this.props.intermediariesSuggestions;
}
}
}
componentWillUnmount() {
console.log(this.props);
document.removeEventListener('mousedown', this.onClickOutside, false);
}
componentWillReceiveProps(nextProps){
console.log(this.props);
if (this.props.suggestionsType === 'competition') {
this.state.suggestions = nextProps.competitionsSuggestions;
}
if (this.props.suggestionsType === 'intermediaries') {
this.state.suggestions = nextProps.intermediariesSuggestions;
}
}
/**
* DOM event handlers
* -------------------------------------------------------------------------*/
onButtonClick = (ev) => {
ev.preventDefault();
const itemIncluded = this.state.items.find(item => item.id === this.state.selection);
if (this.state.selection && !itemIncluded) {
const item =
this.state.suggestions.find(suggestion => suggestion.id === this.state.selection);
this.setState({ items: [...this.state.items, item] });
}
};
onChangeList = (items) => {
const adaptedItems = items
.map(item => ({ label: item.name, id: item.itemName }));
this.setState({ items: adaptedItems });
};
onClickOutside = (ev) => {
if (this.wrapperRef && !this.wrapperRef.contains(ev.target)) {
this.setState({ displayBox: false });
}
};
onSuggestionSelected = (ev) => {
this.setState({
displayBox: false,
value: ev.target.textContent,
selection: ev.target.id });
};
onInputChange = (ev) => {
this.generateSuggestions(ev.target.value);
};
onInputFocus = () => {
this.generateSuggestions(this.state.value);
};
/**
* Helper functions
* -------------------------------------------------------------------------*/
setWrapperRef = (node) => {
this.wrapperRef = node;
};
executeSearch = (value) => {
if (this.props.suggestionsType === 'competition'){
this.props.searchCompetitions(value);
}
if (this.props.suggestionsType === 'intermediaries'){
this.props.searchIntermediaries(value);
}
};
generateSuggestions = (value) => {
if (value.length > MIN_VALUE_TO_SEARCH) {
this.executeSearch(value);
this.setState({ displayBox: true, value, selection: '' });
} else {
this.setState({ displayBox: false, value, selection: '' });
}
};
renderDataSuggestions = () => {
const { listId } = this.props;
const displayClass = this.state.displayBox ? 'suggestions-enabled' : 'suggestions-disabled';
return (
<ul
id={listId}
className={classname(styles['custom-box'], styles[displayClass], styles['select-search-box__select'])}
>
{ this.state.suggestions.length !== 0 ?
this.state.suggestions.map(suggestion => (<li
className={classname(styles['select-search-box__suggestion'])}
onClick={this.onSuggestionSelected}
id={suggestion.get(this.props.suggestionsOptions.id)}
key={suggestion.get(this.props.suggestionsOptions.id)}
>
<span>{suggestion.get(this.props.suggestionsOptions.label)}</span>
</li>))
:
<li className={(styles['select-search-box__no-result'])}>
<span>{NO_SUGGESTIONS_RESULTS}</span>
</li>
}
</ul>
);
};
renderRemovableList = () => {
if (this.state.items.length > 0) {
const adaptedList = this.state.items
.map(item => ({ name: item.name, itemName: item.id }));
return (<RemovableList
value={adaptedList}
className={classname(styles['list-box'])}
onChange={this.onChangeList}
uniqueIdentifier="itemName"
/>);
}
return '';
};
render() {
const input = {
onChange: this.onInputChange,
onFocus: this.onInputFocus,
value: this.state.value
};
return (
<Flex className={styles['form-selectBox']}>
<Box w={1}>
<div
ref={this.setWrapperRef}
className={styles['div-container']}
>
<Input
{...this.props}
input={input}
list={this.props.listId}
inputStyle={classname('form-input--bordered', 'form-input--rounded', styles.placeholder)}
/>
{ this.renderDataSuggestions() }
</div>
</Box>
<Box>
<AppButtonRoundSquareGray type="submit" className={styles['add-button']} onClick={this.onButtonClick}>
Add
</AppButtonRoundSquareGray>
</Box>
<Box>
{ this.renderRemovableList() }
</Box>
</Flex>
);
}
}
SelectBox.propTypes = {
items: PropTypes.instanceOf(Array),
placeholder: PropTypes.string,
listId: PropTypes.string,
className: PropTypes.string
};
SelectBox.defaultProps = {
items: [],
placeholder: 'Choose an option...',
listId: null,
className: ''
};
export default SelectBox;
As you see, in many places i am validating the type of suggestions and do something with that. Its suppose to be a reusable component, and this component could accept any kind of type of suggestions. If this grows, if will have very big validations and i don't want that. So i think that i want something similar to this:
const mapStateToProps = (state, ownProps) => ({
searchString: ownProps.reduxConfiguration.getSearchParam(state),
});
const mapDispatchToProps = (dispatch, ownProps) => ({
dispatchGoToPage: goToPageRequestObj =>
dispatch(ownProps.reduxConfiguration.goToPageRequest(goToPageRequestObj)),
});
const mergeProps = (stateProps, dispatchProps, ownProps) => ({
...ownProps,
search: searchParam => dispatchProps.dispatchGoToPage({
searchParam
}),
...stateProps
});
How can i make something similar to that?
Here are a few things to consider:
The purpose of using Redux is to remove state logic from your components.
What you've currently got has Redux providing some state and your component providing some state. This is an anti-pattern (bad):
// State from Redux: (line 22 - 24)
const mapStateToProps = (state, ownProps) => ({
searchString: ownProps.reduxConfiguration.getSearchParam(state),
});
// State from your component: (line 65 - 71)
this.state = {
displayBox: false,
selection: null,
value: '',
items: [],
suggestions: [],
};
If you take another look at your SelectBox component - a lot of what it is doing is selecting state:
// The component is parsing the state and choosing what to render (line 79 - 86)
if (this.props.suggestionsType){
if (this.props.suggestionsType === 'competition'){
this.state.suggestions = this.props.competitionsSuggestions;
}
if (this.props.suggestionsType === 'intermediaries'){
this.state.suggestions = this.props.intermediariesSuggestions;
}
}
Turns out, this is precisely what mapStateToProps() is for. You should move this selection logic to mapStateToProps(). Something like this:
const mapStateToProps = (state) => {
let suggestions = null;
switch (state.suggestionType) {
case 'competition':
suggestions = state.suggestions.competition;
break;
case 'intermediaries':
suggestions = state.suggestions.intermediaries;
break;
default:
break;
}
return {
suggestions
};
};
Every time the state updates (in Redux) it will pass new props to your component. Your component should only be concerned with how to render its part of the state. And this leads me to my next point: When your application state is all being managed by Redux and you don't have state logic in your components, your components can simply be functions (functional components).
const SelectBox3 = ({ suggestions }) => {
const onClick = evt => { console.log('CLICK!'); };
const list = suggestions.map((suggestion, index) => {
return (
<li key={index} onClick={onClick}>suggestion</li>
);
});
return (
<ul>
{list}
</ul>
);
};
Applying these patterns, you get components that are very easy to reason about, and that is a big deal if you want to maintain this code into the future.
Also, by the way, you don't need to use mergeProps() in your example. mapDispatchToProps can just return your search function since connect() will automatically assemble the final props object for you.:
const mapDispatchToProps = (dispatch, ownProps) => ({
// 'search' will be a key on the props object passed to the component!
search: searchParam => {
dispatch(ownProps.reduxConfiguration.goToPageRequest({ searchParam });
// (also, your 'reduxConfiguration' is probably something that belongs in
// the Redux state.)
}
});
I highly recommend giving the Redux docs a good read-through. Dan Abramov (and crew) have done a great job of laying it all out in there and explaining why the patterns are the way they are.
Here's the link: Redux.
Also, look into async actions and redux-thunk for dealing with asynchronous calls (for performing a search on a server, for example).
Finally let me say: you're on the right track. Keep working on it, and soon you will know the joy of writing elegant functional components for your web apps. Good luck!
I am learning Redux at school, as such we are using tests to insure we have benchmarks passing to help us in our understanding of the building blocks.
I am up to the portion where I am creating the Reducerfunction and I am almost done \o/ however I can't get one test to pass.
1) returns the initial state by default
And below the console spits back...
Reducer returns the initial state by default:
AssertionError: expected undefined to be an object
at Context. (tests/redux.spec.js:103:49)
My thinking it's because the test handles some of the concerns one would be responsible for e.g importing, creating action types etc. But not all. So maybe I am missing something the test is not providing?
Anyway here is my reducer file:
import pet from "../components/PetPreview";
import { createStore } from "redux";
import { adoptPet, previewPet, addNewDog, addNewCat } from "./action-creators";
// ACTION TYPES
const PREVIEW_PET = "PREVIEW_PET";
const ADOPT_PET = "ADOPT_PET";
const ADD_NEW_DOG = "ADD_NEW_DOG";
const ADD_NEW_CAT = "ADD_NEW_CAT";
// INTITIAL STATE
const initialState = {
dogs: [
{
name: "Taylor",
imgUrl: "src/img/taylor.png"
},
{
name: "Reggie",
imgUrl: "src/img/reggie.png"
},
{
name: "Pandora",
imgUrl: "src/img/pandora.png"
}
],
cats: [
{
name: "Earl",
imgUrl: "src/img/earl.png"
},
{
name: "Winnie",
imgUrl: "src/img/winnie.png"
},
{
name: "Fellini",
imgUrl: "src/img/fellini.png"
}
]
// These dogs and cats are on our intial state,
// but there are a few more things we need!
};
export default function reducer(prevState = initialState, action) {
var newState = Object.assign({}, prevState)
console.log('initialState', typeof initialState)
switch (action.type) {
case PREVIEW_PET:
// console.log('newState', newState)
return Object.assign({}, prevState, {
petToPreview: action.pet
});
break
case ADOPT_PET:
return Object.assign({}, prevState, {
petToAdopt: action.pet
});
break
case ADD_NEW_DOG:
// console.log('action', action.dog)
// console.log('prevState.dogs', prevState.dogs)
newState.dogs = prevState.dogs.concat([action.dog])
return newState;
break
case ADD_NEW_CAT:
// console.log('action', action.dog)
// console.log('prevState.dogs', prevState.dogs)
newState.cats = prevState.cats.concat([action.cat])
return newState;
break;
default:
return prevState;
}
return initialState
}
As you can see after the switch block I am returning the initialState
Shouldn't that be it?
Below is the redux.spec.js file:
import { expect } from "chai";
import { createStore } from "redux";
// You will write these functions
import {
previewPet,
adoptPet,
addNewDog,
addNewCat
} from "../src/store/action-creators";
import reducer from "../src/store/reducer";
const DOGS = [
{
name: "Taylor",
imgUrl: "src/img/taylor.png"
},
{
name: "Reggie",
imgUrl: "src/img/reggie.png"
},
{
name: "Pandora",
imgUrl: "src/img/pandora.png"
}
];
const CATS = [
{
name: "Earl",
imgUrl: "src/img/earl.png"
},
{
name: "Winnie",
imgUrl: "src/img/winnie.png"
},
{
name: "Fellini",
imgUrl: "src/img/fellini.png"
}
];
function getRandomPet(pets) {
return pets[Math.floor(Math.random() * pets.length)];
}
describe("Action creators", () => {
describe("previewPet", () => {
it("returns properly formatted action", () => {
const pet = getRandomPet(DOGS);
expect(previewPet(pet)).to.be.deep.equal({
type: "PREVIEW_PET",
pet: pet
});
});
});
describe("adoptPet", () => {
it("returns properly formatted action", () => {
const pet = getRandomPet(DOGS);
expect(adoptPet(pet)).to.be.deep.equal({
type: "ADOPT_PET",
pet: pet
});
});
});
describe("addNewDog", () => {
it("returns properly formatted action", () => {
const pet = getRandomPet(DOGS);
expect(addNewDog(pet)).to.be.deep.equal({
type: "ADD_NEW_DOG",
dog: pet
});
});
});
describe("addNewCat", () => {
it("returns properly formatted action", () => {
const pet = getRandomPet(CATS);
expect(addNewCat(pet)).to.be.deep.equal({
type: "ADD_NEW_CAT",
cat: pet
});
});
});
}); // end Action creators
describe("Reducer", () => {
let store;
beforeEach("Create the store", () => {
// creates a store (for testing) using your (real) reducer
store = createStore(reducer);
});
it("returns the initial state by default", () => {
// In addition to dogs and cats, we need two more fields
expect(store.getState().petToPreview).to.be.an("object");
expect(store.getState().petToAdopt).to.be.an("object");
});
describe("reduces on PREVIEW_PET action", () => {
it("sets the action's pet as the petToPreview on state (without mutating the previous state)", () => {
const prevState = store.getState();
const pet = getRandomPet(DOGS);
const action = {
type: "PREVIEW_PET",
pet: pet
};
store.dispatch(action);
const newState = store.getState();
// ensures the state is updated properly - deep equality compares the values of two objects' key-value pairs
expect(store.getState().petToPreview).to.be.deep.equal(pet);
// ensures we didn't mutate anything - regular equality compares the location of the object in memory
expect(newState.petToPreview).to.not.be.equal(prevState.petToPreview);
});
});
describe("reduces on ADOPT_PET action", () => {
it("sets the action's pet as the petToAdopt on state (without mutating the previous state)", () => {
const prevState = store.getState();
const pet = getRandomPet(DOGS);
const action = {
type: "ADOPT_PET",
pet: pet
};
store.dispatch(action);
const newState = store.getState();
expect(newState.petToAdopt).to.be.deep.equal(pet);
expect(newState.petToAdopt).to.not.be.equal(prevState.petToAdopt);
});
});
describe("reduces on ADD_NEW_DOG action", () => {
it("adds the new dog to the dogs array (without mutating the previous state)", () => {
const prevState = store.getState();
const pet = getRandomPet(DOGS);
const action = {
type: "ADD_NEW_DOG",
dog: pet
};
store.dispatch(action);
const newState = store.getState();
expect(newState.dogs.length).to.be.equal(prevState.dogs.length + 1);
expect(newState.dogs[newState.dogs.length - 1]).to.be.deep.equal(pet);
expect(newState.dogs).to.not.be.equal(prevState.dogs);
});
});
describe("reduces on ADD_NEW_CAT action", () => {
it("adds the new cat to the cats array (without mutating the previous state)", () => {
const prevState = store.getState();
const pet = getRandomPet(CATS);
const action = {
type: "ADD_NEW_CAT",
cat: pet
};
store.dispatch(action);
const newState = store.getState();
expect(newState.cats.length).to.be.equal(prevState.cats.length + 1);
expect(newState.cats[newState.cats.length - 1]).to.be.deep.equal(pet);
expect(newState.cats).to.not.be.equal(prevState.cats);
});
});
describe("handles unrecognized actions", () => {
it("returns the previous state", () => {
const prevState = store.getState();
const action = {
type: "NOT_A_THING"
};
store.dispatch(action);
const newState = store.getState();
// these should be the same object in memory AND have equivalent key-value pairs
expect(prevState).to.be.an("object");
expect(newState).to.be.an("object");
expect(newState).to.be.equal(prevState);
expect(newState).to.be.deep.equal(prevState);
});
});
}); // end Reducer
Thanks in advance!
in the test cases, one of the test case default says
it("returns the initial state by default", () => {
// In addition to dogs and cats, we need two more fields
expect(store.getState().petToPreview).to.be.an("object");
expect(store.getState().petToAdopt).to.be.an("object");
});
meaning there must be petTpPreview and petToAdapt protery attached to the store at the inital itself. this can be done by adding these two as boject to the state as follows.
// INTITIAL STATE
const initialState = {
petToPreview:{},
petToAdopt: {},
dogs: [
{
name: "Taylor",
imgUrl: "src/img/taylor.png"
},
{
name: "Reggie",
imgUrl: "src/img/reggie.png"
},
{
name: "Pandora",
imgUrl: "src/img/pandora.png"
}
],
cats: [
{
name: "Earl",
imgUrl: "src/img/earl.png"
},
{
name: "Winnie",
imgUrl: "src/img/winnie.png"
},
{
name: "Fellini",
imgUrl: "src/img/fellini.png"
}
]
// These dogs and cats are on our intial state,
// but there are a few more things we need!
};
hope it helps!
All paths in the switch statement lead to a return, which means your return initialState on the penultimate line is unreachable.
Also, your newState is nothing but a clone of prevState, and is unnecessary.
Removing that, and adding a helper function for switchcase combined with some es6 spread love, your code becomes
const switchcase = cases => defaultValue => key =>
(key in cases ? cases[key] : defaultValue);
const reducer = (state = initialState, action) =>
switchcase({
[PREVIEW_PET]: { ...state, petToPreview: action.pet },
[ADOPT_PET]: { ...state, petToAdopt: action.pet },
[ADD_NEW_DOG]: { ...state, dogs: [...state.dogs, action.dog] },
[ADD_NEW_CAT]: { ...state, cats: [...state.cats, action.cat] },
})(state)(action.type);
With all the clutter gone, it's glaringly obvious that the problem is in the fact that your code returns the initialState object if action.type === undefined. And your initialState object contains only dogs and cats properties, whereas your test expects there to be petToPreview and petToAdopt properties.
You can add those properties in the initialState or you can change the test depending on what functionality you want.
Shouldn't you return the previous state by default? The by default is the case that the reducer doesn't care about the action, and simply return its current state, which is prevState in your case.