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I have a Form and Input components, which are rendered as below.
<Form>
<Field />
<Field />
<Field />
</Form>
Form component will act as wrapper component here and Field component ref are not being set here. I want iterate through props.children in Form Component and want to assign a ref attribute to each children. Is there any possibility to achieve this?
776
In child component, we create Refs by using React. createRef() and then attached to React elements via the ref attribute. // EXPLANATION: a reference to the node becomes accessible at the current attribute of the ref. In the parent component, we can get a reference to the Input component and call its focus() method.
There is one caveat to the above example: refs will not get passed through. That's because ref is not a prop. Like key , it's handled differently by React. If you add a ref to a HOC, the ref will refer to the outermost container component, not the wrapped component.
then using Refs we can access the child's state. Creating Refs Refs are created using React. createRef() and attached to React elements via the ref attribute. Accessing Refs When we assign a ref to an element or child component in the render, then we can access the element using the current attribute of the ref.
Solution : As I had mentioned earlier — there are no direct ways to mutate a prop directly in child components. However when we pass the props from parent to child, we can also pass the function(with the logic) which changes the props.
You need Form to inject your refs with React.Children and React.cloneElement APIs:
const FunctionComponentForward = React.forwardRef((props, ref) => (
<div ref={ref}>Function Component Forward</div>
));
const Form = ({ children }) => {
const childrenRef = useRef([]);
useEffect(() => {
console.log("Form Children", childrenRef.current);
}, []);
return (
<>
{React.Children.map(children, (child, index) =>
React.cloneElement(child, {
ref: (ref) => (childrenRef.current[index] = ref)
})
)}
</>
);
};
const App = () => {
return (
<Form>
<div>Hello</div>
<FunctionComponentForward />
</Form>
);
};
181
You can map children create new instance of component based on it using one of two ways showed in React Docs.
With React.Children.map and React.cloneElement (this way, key and ref from original element are preserved)
Or only with React.Children.map (Only ref from original component is preserved)
function useRefs() {
const refs = useRef({});
const register = useCallback((refName) => ref => {
refs.current[refName] = ref;
}, []);
return [refs, register];
}
function WithoutCloneComponent({children, ...props}) {
const [refs, register] = useRefs();
return (
<Parent>
{React.Children.map((Child, index) => (
<Child.type
{...Child.props}
ref={register(`${field-${index}}`)}
/>
)}
</Parent>
)
}
function WithCloneComponent({children, ...props}) {
const [refs, register] = useRefs();
return (
<Parent>
{
React.Children.map((child, index) => React.cloneElement(
child,
{ ...child.props, ref: register(`field-${index}`) }
)
}
</Parent>
)
}
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