React Hook : Send data from child to parent component

Question

I\'m looking for the easiest solution to pass data from a child component to his parent.

I\'ve heard about using Context, pass trough properties or update props, but

Answer 1

To make things super simple you can actually share state setters to children and now they have the access to set the state of its parent.

example: Assume there are 4 components as below,

function App() {
  return (
    <div className="App">
      <GrandParent />
    </div>
  );
}

const GrandParent = () => {
  const [name, setName] = useState("i'm Grand Parent");
  return (
    <>
      <div>{name}</div>
      <Parent setName={setName} />
    </>
  );
};

const Parent = params => {
  return (
    <>
      <button onClick={() => params.setName("i'm from Parent")}>
        from Parent
      </button>
      <Child setName={params.setName} />
    </>
  );
};

const Child = params => {
  return (
    <>
      <button onClick={() => params.setName("i'm from Child")}>
        from Child
      </button>
    </>
  );
};

so grandparent component has the actual state and by sharing the setter method (setName) to parent and child, they get the access to change the state of the grandparent.

you can find the working code in below sandbox, https://codesandbox.io/embed/async-fire-kl197

Answer 2

A common technique for these situations is to lift the state up to the first common ancestor of all the components that needs to use the state (i.e. the PageComponent in this case) and pass down the state and state-altering functions to the child components as props.

Example

const { useState } = React;

function PageComponent() {
  const [count, setCount] = useState(0);
  const increment = () => {
    setCount(count + 1)
  }

  return (
    <div className="App">
      <ChildComponent onClick={increment} count={count} />         
      <h2>count {count}</h2>
      (count should be updated from child)
    </div>
  );
}

const ChildComponent = ({ onClick, count }) => {
  return (
    <button onClick={onClick}>
       Click me {count}
    </button>
  )
};

ReactDOM.render(<PageComponent />, document.getElementById("root"));

<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>

<div id="root"></div>

Answer 3

I've had to deal with a similar issue, and found another approach, using an object to reference the states between different functions, and in the same file.

import React, { useState } from "react";

let myState = {};

const GrandParent = () => {
  const [name, setName] = useState("i'm Grand Parent");
  myState.name=name;
  myState.setName=setName;
  return (
    <>
      <div>{name}</div>
      <Parent />
    </>
  );
};
export default GrandParent;

const Parent = () => {
  return (
    <>
      <button onClick={() => myState.setName("i'm from Parent")}>
        from Parent
      </button>
      <Child />
    </>
  );
};

const Child = () => {
  return (
    <>
      <button onClick={() => myState.setName("i'm from Child")}>
        from Child
      </button>
    </>
  );
};

Answer 4

You can create a method in your parent component, pass it to child component and call it from props every time child's state changes, keeping the state in child component.

const EnhancedTable = ({ parentCallback }) => {
    const [count, setCount] = useState(0);
    
    return (
        <button onClick={() => {
            const newValue = count + 1;
            setCount(newValue);
            parentCallback(newValue);
        }}>
             Click me {count}
        </button>
    )
};

class PageComponent extends React.Component { 
    callback = (count) => {
        // do something with value in parent component, like save to state
    }

    render() {
        return (
            <div className="App">
                <EnhancedTable parentCallback={this.callback} />         
                <h2>count 0</h2>
                (count should be updated from child)
            </div>
        )
    }
}