How do I call the openDrawer function on DrawerLayoutAndroid from parent component?

问题

I have made a component which sets up the DrawerLayoutAndroid, which I want to call in my index file.

drawer.js:

export default class MenuDrawer extends Component {
    constructor(props) {
        super(props);
        this.openDrawer = this.openDrawer.bind(this);
    }
    render() {
        var navigationView = (
            // ...
        );
        return (
            <DrawerLayoutAndroid
                ref={(_drawer) => this.drawer = _drawer}
                drawerWidth={200}
                drawerPosition={DrawerLayoutAndroid.positions.Left}
                renderNavigationView={() => navigationView}>
            {this.props.children}
            </DrawerLayoutAndroid>
        );
    }
    openDrawer() {
        this.drawer.openDrawer();
    }
}

I then have everything in the render() function in my index file wrapped around since I want the drawer to be accessible from anywhere. I just cannot figure out how I open the drawer from the index file. I have tried several different ways to call the function, but I always end up getting undefined is not an object.

index.android.js

export default class AwesomeProject extends Component {
    constructor(props) {
        super(props);
        this.openMenu = this.openMenu.bind(this);
    }

    render() {
        const { region } = this.props;
        return (
            <MenuDrawer
                ref={(_menudrawer) => this.menudrawer = _menudrawer}
                style={styles.layout}>
                <TouchableHighlight
                    style={styles.topbar}
                    onPress={this.openMenu}>
                <Text>Open</Text>
                </TouchableHighlight>
            </MenuDrawer>
        );
    }

    openMenu() {
            this.refs.menudrawer.openDrawer();
    }
}

This gives me the error "undefined is not an object (evaluating 'this.refs.menudrawer.openDrawer')".

How do I go about solving this?

Thanks

回答1:

It looks good, you're just accessing the menudrawer incorrectly. It should be:

this.menudrawer.openDrawer();

Because your ref is:

ref={(_menudrawer) => this.menudrawer = _menudrawer}

来源：https://stackoverflow.com/questions/44248593/how-do-i-call-the-opendrawer-function-on-drawerlayoutandroid-from-parent-compone