feat: [mason_logger] support validation for prompt, promptAny, and chooseAny #1550
Description
Description
Logger has some user inputs that accept arbitrary data. It can be useful to validate that user input "inline" with a given user input without having to re-prompt the user for an input.
Requirements
- define
Validator<T>typedef like Flutter'sFormFieldValidator. - add optional
Validator<String>? validatorparameter toLogger.prompt - add optional
Validator<List<String>>? validatorparameter toLogger.promptAny - add optional
Validator<List<T>>? validatorparameter toLogger.chooseAny
Additional Context
Why these methods?
I think these are the only places a validation makes sense since data types are not very constrained compored to the other inputs.
chooseOneis already very limiting with select one (how would you validate "one" item?).confirm's return value is it's "validation" by nature of booleans. "Inline" validation does seem to provide any additional information to the user.
How would this work?
Take this current validation flow for requiring a compatible dart package name.
void main(List<String> arguments) {
final value = collectInput();
print(value);
}
String? validate(String value) {
if (value.contains(' ')) return 'Cannot contain spaces';
if (value.contains('.')) return 'Cannot contain dots';
if (value.contains('-')) return 'Cannot contain hyphen';
// descriptive messages
return null;
}
String collectInput() {
Logger logger = Logger();
String value;
String? validation;
do {
var prompt = 'Dart package name';
if (validation != null) {
prompt = 'Dart package name ${red.wrap(validation)}';
}
value = logger.prompt(prompt, defaultValue: 'my_app');
validation = validate(value);
} while (validation != null);
return value;
}Could be reduced to this kind of flow by passing in the validator directly: validator: validate
void main(List<String> arguments) {
final value = collectInput();
print(value);
}
String? validate(String value) {
if (value.contains(' ')) return 'Cannot contain spaces';
if (value.contains('.')) return 'Cannot contain dots';
if (value.contains('-')) return 'Cannot contain hyphen';
return null;
}
String collectInput() {
Logger logger = Logger();
return logger.prompt(
'Dart package name',
defaultValue: 'my_app',
validator: validate,
);
}How should it look?
I think an "inline" message can use the same style as Logger.theme.warn.
void main(List<String> arguments) {
Logger logger = Logger();
// simulate validation failing
String? validation = logger.theme.warn('Cannot contain spaces');
logger.prompt('Dart package name $validation', defaultValue: 'my_app');
}Dart package name Cannot contain spaces (my_app) my app
When should the
validatorfunction be executed?
If a validator is provided, the function executes when the user submits a value. When validator(value) returns null the value returns as normal to its consumer.