I use React + styled and my question is about the following code
<MobileButton
onClick={props.handleMobileDropdownElementClicked}
padding={isSmallDevice ? 1 : 0}
>
Name
</MobileButton>
Is there a way to generalise this component to write like this without having props and onclick()? like the following code.
<MobileButton>
Name
</MobileButton>
I was just curious if there is things in react or styled component that could do that if we are repeating the same component with the same props/onclick function.
Thank you
Sure, you can make a new component that doesn't require said props. But you'll still have to pass the props when creating that component initially.
For example:
const YourComponent = (props) => {
const NewMobileButton = (newProps) => {
return (
<MobileButton
onClick={props.handleMobileDropdownElementClicked}
padding={isSmallDevice ? 1 : 0}
>
{newProps.children}
</MobileButton>
)
}
return (
<>
<NewMobileButton>1</NewMobileButton>
<NewMobileButton>2</NewMobileButton>
</>
)
}
I'm having trouble understanding the spread operator when I want to pass all other props to a component.
Any help would be appreciated.
import React, { Fragment } from "react";
import SiteCard from "./SiteCard";
const SiteList = ({ sites }) => {
return (
<Fragment>
{sites.map((site) => {
return (
<SiteCard
key={site.login.uuid}
image={site.picture.large}
firstName={site.name.first}
lastName={site.name.last}
city={site.location.city}
country={site.location.country}
sensors={site.dob.age}
otherSiteProps={...site} // how can I pass the site props here?
/>
);
})}
</Fragment>
);
};
export default SiteList;
You are almost there with the solution.
You need to pass it as otherSiteProps={{...site}}.
This is if you want to pass site as an object to otherSiteProps property of SiteCard.
If you want to spread site and have multiple props for component SiteCard you do it like this:
<SiteCard
key={site.login.uuid}
image={site.picture.large}
firstName={site.name.first}
lastName={site.name.last}
city={site.location.city}
country={site.location.country}
sensors={site.dob.age}
{...sites}
/>
This in case that sites is an object. If site is an array, this wont work.
You just need to write:
<SiteCard
key={site.login.uuid}
image={site.picture.large}
firstName={site.name.first}
lastName={site.name.last}
city={site.location.city}
country={site.location.country}
sensors={site.dob.age}
{...site} // how can I pass the site props here?
/>
But wait, why you're making so complicated? You can just use:
<SiteCard {...site} />
Now, in your SiteCard component use required props.
And if I were you, I would not have separated SiteCard component for this scenario. I would just write:
{sites.map((site) => {
return (
// everything here I will utilize in html.
);
})}
Lets say I have a base component that uses forwardRef like so:
const BaseMessage = React.forwardRef((props, ref) => (
<div ref={ref}>
{props.icon}
<h2>{props.title}</h2>
<p>{props.message}</p>
</div>
)
Now I want to create a second component, ErrorMessage that is essentially a copy of the BaseMessage but with a predefined value for props.icon, such that the icon prop is not needed to be set. Otherwise, its an exact copy of BaseMessage.
<ErrorMessage title="Oops!" message="Something went wrong when submitting the form. Please try again." />
I don't want to have to do this, since it feels weird to have two layers of forwardRef going on here:
const ErrorMessage = React.forwardRef(({icon, ...props}, ref) => (
<BaseMessage ref={ref} icon={<svg></svg>} {...props} />
))
Is there a way I can make a clone/copy of BaseMessage without having to reimplement forwardRef for ErrorMessage as well? I know there are utils out there like withProps from recompose but I'd like to avoid using a library if I can.
Try cloneElememt
React.cloneElement(BaseMessage, { icon: '' })
I am writing a ControlledInput component, and in order to have access to the state of the component using ControlledInput, I have a binder prop in ControlledInput.
I'm having a slight issue when using the component:
render() {
const CI = props => <ControlledInput binder={this} {...props} />;
return (
<div style={styles.container}>
<h1>NEW RECIPE</h1>
<ControlledInput binder={this} label={"Title"} />
</div>
);
}
The implementation above works completely fine. However, note the const CI I've defined. I tried to use this so I could just write <CI label={"Title"}/> without the binder since the binder will be the same on all the ControlledInput components I use in a given render method.
The problem with using <CI label={"Title"}/> is that when I type into the input, the input "blurs" and I have to reselect it. This appears to be because the render method creates the CI on every render.
I hope I've explained that clearly, because my head hurts.
Anyway, it makes sense to me why this happens. And I know that one solution is to put const CI = props => <ControlledInput binder={this} {...props} />; outside of the render function. But then I'd have to call it as <this.CI> and that starts to defeat the purpose.
And I can't put CI in global scope because then I don't have access to this.
Is there a way to solve this?
Update
Here is the current (very much in progress) code for ControlledInput:
// #flow
import React, { Component } from "react";
type Props = {
containerStyle?: Object,
label: string,
propName?: string,
binder: Component<Object, Object>,
onChange?: Object => void
};
class ControlledInput extends Component<Props> {
render() {
const props = this.props;
const propName = props.propName || props.label.toLowerCase();
return (
<div style={props.containerStyle}>
<p>{props.label}</p>
<input
type="text"
label={props.label}
onChange={
this.props.onChange ||
(e => {
props.binder.setState({ [propName]: e.target.value });
})
}
value={props.binder.state[propName]}
></input>
</div>
);
}
}
The point of this whole endeavor is to simplify creating a form with controlled components, avoiding having to add value={this.state.whatever} and onChange={e=>this.setState({whatever: e})} to each one, which is not DRY in my opinion.
And then I want get a little more DRY by not passing binder={this} to every component and that's why I'm doing const CI = props => <ControlledInput binder={this} {...props} />;, which, again, has to be inside the class to access this and inside the render function to be called as CI rather than this.CI.
So that first explanation why you need to pass this, although I suppose I could also have props like setState={this.setState} parentState={this.state}, and in that case it does indeed start to make sense to combine those into something like {...propsToSend} as #John Ruddell suggested.
Note that I've provided a possibility to override onChange, and plan on doing so for most or all of the other props (e.g, value={this.props.value || binder.state[propName]}. If one were to override a lot of these (especially value and onChange) it would indeed make the component much less reusable, but the main use case is for quickly creating multiple inputs that don't have special input handling.
So, again, my ideal would be to call <ControlledInput label="Title"/> and have the component code take care of binding state and setState correctly. If this is possible. And then the second option would be to have a place to define the necessary context props in a place that makes it simple when it's time to actually use the component multiple times, like so:
<ControlledInput label={"title"} {...contextProps}/>
<ControlledInput label={"author"} {...contextProps}/>
<ControlledInput label={"email"} {...contextProps}/>
<ControlledInput label={"content"} textArea={true} {...contextProps}/> // textarea prop not implemented yet, fyi
etc
I hear that accessing the parent state/context may be an anti-pattern, but there must be some way to do what I'm trying to do without using an anti-pattern, isn't there?
If you want the state of the parent, handle the state there and pass down the value to your input - ControlledInput won't have to know anything except how to handle data in and out. Something like this, and note that I jacked up the names a little so you can see which component is handling what:
import React, { useState } from "react"
const Parent = () => {
const [title, setTitle] = useState("")
const handleChangeInParent = (newTitle) => {
setTitle((oldValue) => newTitle)
}
return(<div style={styles.container}>
<h1>NEW RECIPE</h1>
<ControlledInput handleChange={handleChangeInParent} label={title} />
</div>)
}
const ControlledInput = ({handleChange, label}) => {
return (
<input onChange={handleChange} type="text" value={label} />
)
}
If ControlledComponent needs to handle its own state, then pass it a default value and then have the Parent read the value when saving (or whatever):
import React, { useState } from "react"
const Parent = () => {
const handleSaveInParent = (newTitle) => {
console.log("got the new title!")
}
return (
<div style={styles.container}>
<h1>NEW RECIPE</h1>
<ControlledInput handleSave={handleSaveInParent} initialLabel="Title" />
</div>
)
}
const ControlledInput = ({ handleSave, initialLabel }) => {
const [title, setTitle] = useState(initialLabel)
const handleChange = (ev) => {
const value = ev.target.value
setTitle((oldValue) => value)
}
const handleSubmit = (ev) => {
ev.preventDefault()
handleSave(title)
}
return (
<form onSubmit={handleSubmit}>
<input onChange={handleChange} type="text" value={title} />
</form>
)
}
You shouldn't be sending this through - just send values and/or functions to handle values.
With Updated Implementation
(okay, John you win!)
Not positive if this is technically an "answer", but I've rewritten the component to take a state and (updated) a setterFn prop:
component
// #flow
import React, { Component } from "react";
type Props = {
containerStyle?: Object,
labelStyle?: Object,
label: string,
propName?: string,
state: Object,
onChange?: Object => void,
textArea?: boolean,
setterFn: (key: string, value: mixed) => void
};
class ControlledInput extends Component<Props> {
render() {
const props = this.props;
const propertyName = props.propName || props.label.toLowerCase();
const TagType = props.textArea ? "textarea" : "input";
// only pass valid props to DOM element (remove any problematic custom props)
const { setterFn, propName, textArea, ...domProps } = props;
return (
<div style={props.containerStyle}>
<p style={props.labelStyle}>{props.label}</p>
<TagType
{...domProps}
label={props.label} // actually could get passed automatically, but it's important so I'm leaving it in the code
onChange={
this.props.onChange ||
(setterFn ? e => setterFn(propertyName, e.target.value) : null)
}
value={props.state[propertyName] || ""}
></TagType>
</div>
);
}
}
export default ControlledInput;
in use (somehow less code than before!)
class Wrapper extends Component<Object, Object> {
state = {};
render() {
const setterFn = (k, v) => this.setState({ [k]: v });
const p = { state: this.state, setterFn: setterFn.bind(this) };
return <ControlledInput {...p} {...this.props.inputProps} />
}
}
I guess this is more appropriate. It still takes up a lot more space than binder={this}.
It doesn't actually the questions of:
How to access the parent's state from the component. Though from comments it seems like this is an anti-pattern, which I do understand from the theory of React.
How to set these repeating props elsewhere so that I can just call `. I guess the only solution is to do something like this:
render() {
const props = {state: this.state, setState: this.setState}
<ControlledInput {...props} label="Title"/>
}
Which certainly isn't such a bad solution. Especially if I shorten that name to, say, a single character.
Much thanks to #John Ruddell for setting me on the right path.
const HiContainer => (props) {
render{
return(
<h1>Hi {this.props.greet}</h1>
)
}
}
ReactDOM.render(
<HiContainer greet="hi"/>
document.getElementById('root')
);
What's wrong with this code? It's hard to debug I can't see which lines has problem in the console.
Also when do I need to use constructor?
You have some syntax errors, should be
const HiContainer = (props) => {
return(
<h1>Hi {props.greet}</h1>
)
}
and can be simplify to:
const HiContainer = props => <h1>Hi {props.greet}</h1>
You may need to learn from the basics, this is arrow function:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions
Problem is, you are using the arrow function in a wrong way.
It should be like this const HiContainer = () => {}.
Try this it will work:
const HiContainer = (props) => {
return(
<h1>Welcome {props.greet}</h1>
)
}
ReactDOM.render(
<HiContainer greet="hi"/>,
document.getElementById('app')
);
constructor is required when you use stateful components, and store the information in state variable, since you are using stateless components, constructor is not required.
Check jsfiddle for working example: https://jsfiddle.net/ej2szg3a/
Check this for Stateless Function Components: https://www.reactenlightenment.com/react-state/8.4.html
Seems like you're using functional component, which handles render method automatically.
The code should be:
const HiContainer = (props) => (
<h1>Hi {props.greet}</h1>
)
If you want to add lifecycle methods to the component, you need to convert it to class component.