React: Passing down props to functional components

Jose picture Jose · Oct 10, 2016 · Viewed 55.3k times · Source

I have a seemingly trivial question about props and functional 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 functional 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? Thanks in advance.

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);
    }
};

Functional (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 functional component has got me a bit confused. i.e:

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

Answer

finalfreq picture finalfreq · Oct 10, 2016

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.