isDoubleString function
Validates that the String can be parsed as a double
(e.g. '123.45', '-1e3')
Implementation
IValidator isDoubleString() =>
isType<String>() &
validator(
(value) => double.tryParse(value.trim()) != null,
(value) => Expectation(
message: 'a valid formatted double String', value: value, code: 'value.format_invalid', data: {'format': 'double'}),
);