CODEWITHSUNDEEP
javascriptreactjscomponents
Jose
Jose

Reputation: 5200

React: Passing props to function components

I have a seemingly trivial question about props and function components. Basically, I have a container component which renders a Modal component upon state change which is triggered by user click on a button. The modal is a stateless function component that houses some input fields which need to connect to functions living inside the container component.

My question: How can I use the functions living inside the parent component to change state while the user is interacting with form fields inside the stateless Modal component? Am I passing down props incorrectly?

Container

export default class LookupForm extends Component {
    constructor(props) {
        super(props);
        
        this.state = {
            showModal: false
        };
    }
    render() {
        let close = () => this.setState({ showModal: false });

        return (
            ... // other JSX syntax
            <CreateProfile fields={this.props} show={this.state.showModal} onHide={close} />
        );
    }

    firstNameChange(e) {
      Actions.firstNameChange(e.target.value);
    }
};

Function (Modal) Component

const CreateProfile = ({ fields }) => {
  console.log(fields);
  return (
      ... // other JSX syntax
      
      <Modal.Body>
        <Panel>
          <div className="entry-form">
            <FormGroup>
              <ControlLabel>First Name</ControlLabel>
              <FormControl type="text"
                onChange={fields.firstNameChange} placeholder="Jane"
                />
            </FormGroup>
  );
};

Example: say I want to call this.firstNameChange from within the Modal component. I guess the "destructuring" syntax of passing props to a function component has got me a bit confused. i.e:

const SomeComponent = ({ someProps }) = > { // ... };

Upvotes: 83

Views: 230710

Answers (5)

Michael Freidgeim
Michael Freidgeim

Reputation: 28435

A variation of finalfreq's answer

You can pass some props individually and all parent props if you really want (not recommended, but sometimes convenient)

<CreateProfile
  {...this.props}
  show={this.state.showModal}
/>

and then in the CreateProfile component you can just do

const CreateProfile = (props) => {

and destructure the props individually

const {onFirstNameChange, onHide, show }=props;

Upvotes: 6

Krishna Jangid
Krishna Jangid

Reputation: 5410

just do this on source component

 <MyDocument selectedQuestionData = {this.state.selectedQuestionAnswer} />

then do this on destination component

const MyDocument = (props) => (
  console.log(props.selectedQuestionData)
);

Upvotes: 4

Shreekanth
Shreekanth

Reputation: 859

I'm using react function component
In parent component first pass the props like below shown

import React, { useState } from 'react';
import './App.css';
import Todo from './components/Todo'



function App() {
    const [todos, setTodos] = useState([
        {
          id: 1,
          title: 'This is first list'
        },
        {
          id: 2,
          title: 'This is second list'
        },
        {
          id: 3,
          title: 'This is third list'
        },
    ]);

return (
        <div className="App">
            <h1></h1>
            <Todo todos={todos}/> //This is how i'm passing props in parent component
        </div>
    );
}

export default App;

Then use the props in child component like below shown

function Todo(props) {
    return (
        <div>
            {props.todos.map(todo => { // using props in child component and looping
                return (
                    <h1>{todo.title}</h1>
                )
            })}
        </div>  
    );
}

Upvotes: 37

MwamiTovi
MwamiTovi

Reputation: 2502

An addition to the above answer.

If React complains about any of your passed props being undefined, then you will need to destructure those props with default values (common if passing functions, arrays or object literals) e.g.

const CreateProfile = ({
  // defined as a default function
  onFirstNameChange = f => f,
  onHide,
  // set default as `false` since it's the passed value
  show = false
}) => {...}

Upvotes: 6

finalfreq
finalfreq

Reputation: 6980

You would need to pass down each prop individually for each function that you needed to call 

<CreateProfile
  onFirstNameChange={this.firstNameChange} 
  onHide={close}
  show={this.state.showModal}
/>

and then in the CreateProfile component you can either do 

const CreateProfile = ({onFirstNameChange, onHide, show }) => {...}

with destructuring it will assign the matching property names/values to the passed in variables. The names just have to match with the properties

or just do

const CreateProfile = (props) => {...}

and in each place call props.onHide or whatever prop you are trying to access.

Upvotes: 104

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