Edit: I have made it work by getting the target.value from the list, passing that to firstComp.js . Where the onChange method is below, but is this the best practice?
onchange = (e) =>{
let name= e.target.value
let currentName= this.state.foodData.map((item)=>{
if(name==item.name){
console.log(item)
}
})
}
Im doing stephen griders course on react, and trying to implement what he teaches on a personal project, but I cant wrap my head around it.
I have a list, that is looping through an array of objects. When I pick something from that list, I want it to update the state with that object.
The Layout..
DropDownList.js = return a drop down list with all the ingredient names in foodData
DropDownItem = loops through the foodData, returning an option value for each one.
foodData .js = db that looks something like this..
let foodData=[
{"name":"MCT Oil", "brand":"Keppi Keto", "servings":1}
{"name":"Chunky Peanut Butter", "brand":"Skippy"}
]
firstComp.js
import React, { Component} from 'react'
import ReactDOM from 'react-dom'
import foodData from './food/foodData.js'
import DropDownList from './DropDownList.js'
class Layout extends Component {
constructor () {
super()
this.state = {
foodData:foodData,
selectedFood:''
}
this.onchange =this.onchange.bind(this)
}
onchange = (e) =>{
console.log(e.target.value)
}
render () {
return (<div className='home'>
<DropDownList foodData={this.state.foodData} onchange={this.onchange} />
</div>)
}
}
const app = document.getElementById('app')
ReactDOM.render(<Layout />, app)
DropDownList.js
import React from 'react'
import DropDownItem from './DropDownItem.js'
const DropDownList = (props) =>{
****let textInput = React.createRef();**** //REFS
const ingredientItems = props.foodData.map((ingredient, i)=>{
return<DropDownItem key={i} ingredient={ingredient} **ref={textInput}**//REFS />
})
return(
<select value={ingredientItems.name} onChange ={ (e) => props.onchange(e)} >
{ingredientItems}
</select>
)
}
export default DropDownList;
DropDownItem.js
import React from 'react'
const DropDownItem = ({ingredient}) =>{
const itemName = ingredient.name
return(<option value={itemName}>{itemName}</option> )
}
export default DropDownItem;
You don't need to use refs here. You can use some kind of handleChange function in your DropdownList component and send back the value to parent component.
const DropDownList = (props) => {
const handleChange = e => props.onchange( e.target.value );
const ingredientItems = props.foodData.map((ingredient) =>
<DropDownItem key={ingredient.name} ingredient={ingredient} /> );
return (
<select onChange={handleChange}>
{ingredientItems}
</select>
)
}
and in the parent component:
class Layout extends Component {
state = {
foodData,
selectedFood: foodData[0]
};
onchange = name =>
this.setState({
selectedFood: foodData.filter(food => food.name === name)[0]
});
render() {
return (<div className='home'>
<DropDownList foodData={this.state.foodData} onchange={this.onchange} />
</div>)
}
}
or without struggling with values and filter, we can use e.target.options.selectedIndex
as OP finds out him/herself :) This is a cleaner way and works as this (only related parts) :
DropdownList.js
const handleChange = e => props.onchange( e.target.options.selectedIndex);
Layout.js
onchange = index => this.setState({ selectedFood: foodData[index] });
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