Can't call setState (or forceUpdate) on an unmounted component

Question

I\'m trying to fetch the data from the server after component has been updated but I couldn\'t manage to do that. As far as I understand componentWillUnmount is cal

Answer 1

The accepted answer works, and is a valid workaround for the problem of calling asynchronous functions in the component rendering methods (getInitialState, componentWillMount, componentDidMount).

But a better practice would be to use state management helpers like Redux and Flux and a global store, this might avoid the problem of multiple setStates.

Answer 2

A common pattern I use in this instance is something along the lines of

componentWillUnmount() {
    this.isCancelled = true;
}

And then in the code where you're awaiting an async function to resolve, you would add a check before setting state:

async componentDidUpdate(prevProps, prevState) {
    if (this.props.subject.length && prevProps.subject !== this.props.subject) {
        let result = await this.getGrades({
            student: this.props.id,
            subject: this.props.subject
        });
        !this.isCancelled && this.setState({
            subject: this.props.subject,
            grades: result
        });
    }
}

That will stop any state setting on unmounted/unmounting components