Datepicker: Cannot be cleared (due to internal state conditional)

[prescod]

The following example shows three different attempts to clear an input a datepicker. All failed. I have a workaround but it seems to me that it should be coded such that at least one of them works to clear input.

https://gist.github.com/prescod/724c19066b8aa206a6d210c15b077596

My workaround is to change the key and therefore clear the input by re-creating it.

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[interactivellama]

This appears to be an issue with https://github.com/salesforce/design-system-react/blob/master/components/date-picker/date-picker.jsx#L286

which is never going to update based on anything falsey due to the nextProps.value && this.props.value conditional.

Adding this seems to fixed it, except the propType warning still triggers.

		} else if (!nextProps.value) {
			this.setState({
				value: nextProps.value,
				formattedValue: this.props.formatter(nextProps.value),
				inputValue: this.props.formatter(nextProps.value),
			});
		}

The problem with allowing undefined is Datepicker is one of the older components that doesn't have to be controlled, and there value doesn't have to be passed in. I'd love to remove state from all uncontrolled components, but it would break Datepicker for folks.

Clearing only on empty string might work though. ''

[prescod]

Empty string would be a good solution, as long as it is the documented way to clear it.

If you wanted a "type-safe" false-y value, new Date(undefined) is also an option.

[interactivellama]

I think the best solution is adding the lines above and allowing for a string type in the PropTypes. It seems to me if you allow users to type in an input, you should allow a string, too. This is also the same behavior as when all of componentWillReceiveProps is removed.

I can put this on my backlog to do or you can pull request it. We will need at least one unit test with empty string to make sure this doesn't regress in the future.