redux-form format input ONLY onBlur

Question

In my form I have an "amount" field which should always display 2 decimal digits. So, for example if the user types 3, it should be converted to 3.00. If he types 3.1234525 it should become 3.12.

In order to do this I rely on the onBlur prop. Basically onBlur I run a function that formats the number correctly and I try to set the new value on the field.

Here's my code:

 import { blur as blurField } from 'redux-form/immutable'; ... const mapDispatchToProps = { blurField, }; ... export default connect(mapStateToProps, mapDispatchToProps)(Amount); 

class AmountContainer extends Component {
    props: PaymentMethodPropsType;

    formatAmount(event) {
        const {
            blurField,
        } = this.props;
        blurField('myForm', 'amount', formatNumber(event.currentTarget.value, 2));
    }

    /**
     * Render method for the component
     * @returns {Element<*>} the react element
     */
    render() {
        const {
            t,
            amountValue,
        } = this.props;

        const amountLabel = t('form')('amountLabel');

        return (
            <Amount
                amountLabel={amountLabel}
                amountValue={amountValue}
                normalize={onlyNumbersDecimals}
                onBlur={(event: Event) => this.formatAmount(event)}
                validation={[
                    isRequired(t('validation')('amountRequired')),
                    number(t('validation')('amountNotNumber')),
                ]}
            />
        );
    }
}

Let's say I input the number 3 and then I move to the next field in the form. I can see the following actions being called:

{type: "@@redux-form/BLUR", meta: {…}, payload: "3.00"}
{type: "@@redux-form/BLUR", meta: {…}, payload: "3"}

As a result the input value remains 3. It looks like the initial onBlur event "overwrites" the one I trigger calling blurField

Answer 1

Just using the event.preventDefault will work:

formatAmount(event) {
    const {
        blurField,
    } = this.props;
    event.preventDefault();
    blurField('myForm', 'amount', formatNumber(event.currentTarget.value, 2));
}

Answer 2

Hey so this is a little late but I've found an effective and simply way of going about this. I send in the on blur prop, bind the function to the forms scope, and use the built in redux-form function ( change ) to update the field value with the formatted value. The funny thing with this technique, is you need to use a setTimeout set the execution time to 0, for this to work properly. ex.

onBlur={e => {
  let value = e.target.value;
  * Format or update value as needed *
  setTimeout(() => this.props.change(* FIELD NAME *, value));
}}