I'm implementing a Task App where I have two views to render Tasks and Items and one where I render multiple lists based on the Task Status as kanban board.
My reducer:
export const rootReducer = Redux.combineReducers({
Tasks: TasksReducer,
itemsAreLoading: itemsAreLoadingReducer
});
const TasksReducer = (state , action ) => {
if (typeof state == "undefined") {
console.log('state undefined');
return null;
}
switch (action.type) {
case TasksTypes.Tasks_GET:
return action.Tasks;
default:
console.log(state);
return state;
}
}
export class TasksApp extends React.Component {
constructor(props) {
super(props);
}
render() {
const {tasks} = this.props;
return (<div>
<ItemsView Tasks={tasks}/>
<BoardView Lanes=[/* tasks tranfromed into mutliple list based on their status*/]/>
</div>);
}
}
const mapStateToProps = (state) => {
return {
tasks: state.Tasks
};
};
My Question is where to transform the data for the second view to have a different representation of the data.
The main problem here is that you dont fire any actions in your class, and I dont see any actions here neither. So first, you have to fire an action, and dispatch it with the type and payload, second, as David Tyron wrote, the syntax was a bit off in this line:
const { tasks } = this.props;
And for the end a small remark, you can do some destruction in the mapStateToProps function:
const mapStateToProps = ({ Tasks }) => {
return { Tasks };
};
And then get it like const { Tasks } = this.props;
I think, that the best practice to change your tasks props is to fire another action that creates a new props from your tasks props, something like:
export const transformData = tasks => {
return dispatch => {
//Do the transformations here
dispatch {
type: TRANSFORM_DATA,
payload: transformed_tasks
}
}
}
And then catch it with a reducer.
And IMHO, the best place to call this action is the componentDidMount()
Related
I don't understand why React not update my object. In another component through the dispatch I update the state. In this (in code below) code in mapStateToProps categories are changing (console log show one more category). But component not rerender, although in component in useEffect I use props.categories. Event console.log in element does not run
const LeftSidebar = (props: any) => {
console.log('not render after props.categories changed')
useEffect(() => {
props.dispatch(getCategories())
}, [props.categories]);
const addCategoryHandler = (categoryId: number) => {
props.history.push('/category/create/' + categoryId)
};
return (
<div className='left-sidebar'>
<Logo/>
<MenuSidebar categories={props.categories} onClickAddCategory={addCategoryHandler}/>
</div>
);
};
function mapStateToProps(state: State) {
const categories = state.category && state.category.list;
console.log('this categories changes, but LeftSidebar not changing')
console.log(categories)
return { categories };
}
export default connect(mapStateToProps)(LeftSidebar);
I thought if i update state, react update components dependent on this state. How should it work? how should it work? It may be useful, the item that adds the category is not a parent or child, it is a neighbor
My reducer
import {CATEGORIES_GET, CATEGORY_CREATE} from "../actions/types";
export default function (state={}, action: any) {
switch (action.type) {
case CATEGORIES_GET:
return {...state, list: action.payload};
case CATEGORY_CREATE:
return {...state, list: action.payload};
default: return state;
}
}
Thanks for solving problem. All problem was in inmutable data. I used fixtures, and not copied properly array
import {CATEGORIES_GET, CATEGORY_CREATE} from "./types";
import {categoryMenuItems as items} from "../../fixtureData";
import {NewCategory} from "../../types";
let categoryMenuItems = items; // My mistake, I used not immutable value. Not use fixtures for state))
let id = 33;
export function getCategories() {
return {
type: CATEGORIES_GET,
payload: categoryMenuItems
}
}
export function createCategory(newCategory: NewCategory) {
id++
const category = {
title: newCategory.name,
id: id
};
// MISTAKE I use same array, not cloned like let clonedCategoryMenuItems = [...categoryMenuItems]
categoryMenuItems.push(category);
return {
type: CATEGORY_CREATE,
payload: categoryMenuItems
}
}
Not use fixtures for state, use real api :)
Maybe your state not is inmutable. In your reducer use spread operator to add new items
{
list: [
...state.list,
addedCategory
]
}
Instead of
state.list.push(addedCategory)
Im trying to make an api request from redux then take that data and put it in my react state (arrdata). The api call works but i cant seem to get the state on my app.js to update based on the redux api call. Am i missing something?
App.js
class App extends Component {
constructor(props) {
super(props);
this.state = {
arrdata: []
};
}
componentDidMount() {
this.props.loadData();
console.log(this.props.data);
}
render() {
const {arrdata} = this.state
return ( ......)}}
const mapStateToProps = state => {
return {
data: state.data
};
};
export default connect(mapStateToProps, dataAction)(App);
Action
export function loadData() {
return dispatch => {
return axios.get("https://api.coincap.io/v2/assets").then(response => {
dispatch(getData(response.data.data.slice(0, 10)));
});
};
}
export function getData(data) {
return {
type: "GET_DATA",
data: data
};
}
Reducer
let initialState = {
data: []
};
const mainReducer = (state = initialState, action) => {
if (action.type === "GET_DATA") {
return {
...state,
data: action.data
};
} else {
return {
...state
};
}
};
export default mainReducer;
I think you are misleading store with state. Your arrdata is empty since it's stored inside state, but your data comes from props.
Anyways, arrdata in state remains empty, since you are not setting the state anywhere. To do that, you would have to use e.g. getDerivedStateFromProps lifecycle hook, however I wouldn't recommend that.
render() {
const { data } = this.props;
console.log(this.props.data);
return (
// do something with your data
);
}
It should log your data properly.
Note: You don't need state, actually. It's a better approach to manipulate over props, instead of saving data from props into state (in most cases).
So i'm doing a API GET request and set the data on reducer, but the component render twice, first before dispatch and another after, the first one is causing map function problem
what can i do to avoid render twice and solve map function problem?
App.js
componentDidMount(){
this.props.carregarLojas();
}
render(){
const { lojasTeste } = this.props;
//rendering 2 times
console.log(lojasTeste);
return(
<div>
lojasTeste.map((i, index) => (
<h1>{i.name}</h1>
))
</div>
)
}
const mapStateToProps = store => ({
lojasTeste: store.lojaState.lojasTeste
});
const mapDispatchToProps = dispatch => {
return {
carregarLojas: () => {
dispatch(carregarLojas());
}
};
};
export default connect(mapStateToProps, mapDispatchToProps)(App);
Action.js
export const setarLojas = (lojas) =>{
return {
type: SETAR_LOJAS,
data: lojas
}
}
export const carregarLojas = () => {
return (dispatch) => {
return API.get('loja')
.then(response => {
dispatch(setarLojas(response.data))
})
.catch(error => {
throw(error);
})
}
Reducer.js
const initialState ={
lojasTeste: {}
}
export const lojaReducer = (state = initialState, action) => {
switch (action.type){
case SETAR_LOJAS:
return {
...state,
lojasTeste: action.data
}
default:
return state;
}
}
The double render is totally normal:
Your component render once, then call the carregarLojas method which is async. When resolved, the method will update your redux store, which is connected with the props of your component (mapStateToProps). When a prop is updated, it cause automatically a rerender.
Also, for your map problem, you didn't initialized lojasTeste as an array, but as an object. You can't use map on an object (cf https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Objets_globaux/Array/map)
Is is correct to pass a reducer as props when i'm using a rootreducer ?
This is my rootReducer.js :
import { combineReducers } from 'redux';
import simpleReducer from './simpleReducer';
import messageReducer from './messageReducer';
import NewReducer from './NewReducer';
export default combineReducers({
simpleReducer,messageReducer,NewReducer
});
And this is one of my action creators addMessage.js
export const addMessage = (message) => dispatch => {
dispatch({
type: 'ADD',
message: message
})
}
Here is the first reducer messageReducer.js
export default (state = [], action) => {
switch (action.type) {
case 'ADD':
return [
...state,
action.message
];
default:
return state;
}
};
And here is another one simpleReducer.js
export default (state = {}, action) => {
switch (action.type) {
case 'SIMPLE_ACTION':
return {
result: action.payload
}
default:
return state
}
}
And finally here is my last reducer NewReducer.js
export default (state = '', action) => {
switch (action.type) {
case 'AnyThing':
return action.WhatToDisplay;
default:
return state;
}
};
Here is my mapping in the App.js
const mapStateToProps = state => ({
...state
})
const mapDispatchToProps = dispatch => ({
simpleAction: () => dispatch(simpleAction()),
submitNewMessage: (message) => {
dispatch(addMessage(message))
},
NewAction: () => dispatch(NewAction())
})
And here is my ِApp Component.Notice my last 2 h2 tags as well as my ul tag .Without me adding the reducer at the end of the prop , it doesn't work.So
is what i'm doing right ? or is there another way to show the redux state in
my react ?.Note that i currently have no errors and the code functions well.I
just wana know if what i am doing is right or wrong and if there is a better
syntax to show the redux state in my create react app.
class App extends Component {
constructor(props) {
super(props);
this.state = {
input: ''
}
this.handleChange = this.handleChange.bind(this);
this.submitMessage = this.submitMessage.bind(this);
}
handleChange(event) {
this.setState({
input: event.target.value
});
}
submitMessage() {
this.props.submitNewMessage(this.state.input);
this.setState({
input: ''
});
}
simpleAction = (event) => {
this.props.simpleAction();
}
localNormalFunction=(event)=>{
this.props.NewAction()
}
render() {
return (
<div >
<h1>fjasgdasdsg</h1>
<button onClick={this.simpleAction}>Test redux action</button>
<pre>
{
JSON.stringify(this.props)
}
</pre>
<h2>Type in a new Message:</h2>
<input
value={this.state.input}
onChange={this.handleChange}/><br/>
<button onClick={this.submitMessage}>Submit</button>
<ul>
{this.props.messageReducer.map( (message,idx) => {
return (
<li key={idx}>{message}</li>
)
})
}
</ul><br/><br/>
<button onClick={this.localNormalFunction}>dsadsdsa</button>
<h2>{this.props.NewReducer}</h2>
<h2>{this.props.simpleReducer.result}</h2>
</div>
);
}
}
It is better practice to get only the props you need from redux in each component. If you pass the whole redux state in mapStateToProps then whenever anything in redux changes you will have everything rerendering even if nothing you use changed.
One common reason you might be getting errors is that you are trying to use the props in render and they get instantiated afterwards.
Try this give default values to the props if you can't get them from redux:
App.defaultProps = {
result: '',
NewReducer: '',
messageReducer: []
}
const mapStateToProps = state => ({
result: state.simpleReducer.result,
NewReducer: state.NewReducer,
messageReducer: state.messageReducer
})
and then change this.props.simpleReducer.result to this.props.result
I am trying to develop an application, that is showing photos from Unsplash given a keyword. I managed to fetch specific photos using unsplash.js:
actions:
export function fetchPhotos(term) {
const unsplash = new Unsplash({
applicationId:
"id",
secret: "secret",
callbackUrl: "callback"
});
const response = unsplash.search
.photos(term, 1, 20)
.then(toJson)
.then(json => json);
return {
type: FETCH_PHOTOS,
payload: response
};
}
export function setCategory(term) {
return {
type: SET_CATEGORY,
categories: [term]
};
}
export function sortPhotos(attribute) {
return {
type: SORT_PHOTOS,
attribute
}
}
Component that renders the photos:
import React, { Component } from "react";
import { connect } from "react-redux";
import SinglePhoto from "../components/SinglePhoto";
class PhotoList extends Component {
renderPhotos() {
const { photos } = this.props;
console.log(photos);
if (!photos) {
return <p>Loading...</p>;
}
return photos.map(photo => {
const url = photo.urls.full;
const id = photo.id;
const alt = photo.description;
return <SinglePhoto url={url} key={id} alt={alt} />;
});
}
render() {
return <div>{this.renderPhotos()}</div>;
}
}
function mapStateToProps(state) {
return {
photos: state.photos,
categories: state.categories
};
}
export default connect(mapStateToProps)(PhotoList);
And reducers:
import { FETCH_PHOTOS, SORT_PHOTOS } from "../actions/types";
export default function(state = [], action) {
switch (action.type) {
case FETCH_PHOTOS:
return [...action.payload.results];
case SORT_PHOTOS:
break;
default:
return state;
}
}
What I am struggling to do is to actually sort the array of data I receive from the API according to a specific term. The response is an array of objects that makes it impossible to call it in an external component I've called Buttons that I have wanted to set the logic in:
class Buttons extends Component {
render() {
const { created_at: date } = this.props.photos;
console.log(this.props);
return (
<div className="buttons">
{/* <button onClick={() => this.props.sortPhotos(date)}>Sort by creation date</button> */}
</div>
)
}
}
const mapStateToProps = (state) => {
return {
photos: state.photos
}
}
const mapDispatchToProps = (dispatch) => bindActionCreators({sortPhotos}, dispatch);
export default connect(mapStateToProps, mapDispatchToProps)(Buttons);
As I would need to loop over the photos to actually receive their created_at props.
I would like to sort them, for example, taking created_at into account. This would be handled by a button click (there would be other buttons for let's say likes amount and so on). I tried to do this in mapStateToProps until the moment I realized it would be impossible to call this with onClick handler.
As I have read this post, I thought it would be a great idea, however, I am not sure, how can I handle this request by an action creator.
Is there any way that I could call sorting function with an onclick handler?
One approach you can take is using a library such as Redux's reduxjs/reselect to compute derived data based on state, in this case sorted items based on some object key and/or direction. Selectors are composable and are usually efficient as they are not recomputed unless one of its arguments changes. This approach is adding properties to the reducer's state for sort key and sort order. As these are updated in the store via actions/reducers, the selector uses state to derive the elements in the resulting sorted order. You can utilize the sorted items in any connected component.
I've tried my best to recreate a complete example including actions, reducers, selectors, and store structure.
Actions - Created actions for setting sort key/direction. My example is using redux-thunk for handling async actions, but that is in no way necessary:
export const SET_SORT = 'SET_SORT';
const setSort = (sortDirection, sortKey) => ({
type: SET_SORT,
sortDirection,
sortKey
});
export const sort = (sortDirection = 'desc', sortKey = 'created_at') => dispatch => {
dispatch(setSort(sortDirection, sortKey));
return Promise.resolve();
};
Reducer - Updated initial state to keep track of a sort key and/or sort direction with photo objects being stored in a child property such as items:
const initialState = {
isFetching: false,
sortDirection: null,
sortKey: null,
items: []
};
const photos = (state = initialState, action) => {
switch (action.type) {
case FETCH_PHOTOS:
return {
...state,
isFetching: true
};
case RECEIVE_PHOTOS:
return {
...state,
isFetching: false,
items: action.photos
};
case SET_SORT:
return {
...state,
sortKey: action.sortKey,
sortDirection: action.sortDirection
};
default:
return state;
}
};
Selector - Using reselect, create selectors that retrieves items/photos, sortOrder, and sortDirection. The sorting logic can obviously be enhanced to handle other keys/conditions/etc:
import { createSelector } from 'reselect';
const getPhotosSelector = state => state.photos.items;
const getSortKeySelector = state => state.photos.sortKey;
const getSortDirectionSelector = state => state.photos.sortDirection;
export const getSortedPhotosSelector = createSelector(
getPhotosSelector,
getSortKeySelector,
getSortDirectionSelector,
(photos, sortKey, sortDirection) => {
if (sortKey === 'created_at' && sortDirection === 'asc') {
return photos.slice().sort((a, b) => new Date(a.created_at) - new Date(b.created_at));
} else if (sortKey === 'created_at' && sortDirection === 'desc') {
return photos.slice().sort((a, b) => new Date(b.created_at) - new Date(a.created_at));
} else {
return photos;
}
}
);
Component - Utilize selector to render items. Trigger dispatch of sort action via button click passing in a sort key and/or sort order. The linked example uses dropdowns in combination with the button click to set sort key/order:
import { getSortedPhotosSelector } from './selectors';
// ...
handleClick() {
this.props.dispatch(sort('desc', 'created_at'));
}
render() {
const { sortDirection, sortKey, items } = this.props;
<ul>
{items.map(item => <li key={item.id}>{item.created_at}</li>)}
</ul>
<button type="button" onClick={this.handleClick}>SORT</button>
}
const mapStateToProps = state => ({
items: getSortedPhotosSelector(state),
sortKey: state.photos.sortKey,
sortDirection: state.photos.sortDirection
});
export default connect(mapStateToProps)(PhotoList);
Here is a StackBlitz, demonstrating the functionality in action. It includes controlled components such as and to trigger dispatch of a sort action.
Hopefully that helps!