Include "space" check in email adress flutter - dart

Question

Can someone please tell me how to
add "space" check in email address? I
have tried email.contains("") bt it didnt
worked.
I don't get a error when i type invalid email
import 'dart:async';
class Validators{
final validEmail = StreamTransformer<String, String>.fromHandlers(
handleData: (email, sink){
if(email.contains('#')){
sink.add(email);
}else if(email.contains(" ")){
sink.addError('Enter a valid email');
}else{
sink.addError('Enter a valid email');
}
}
);
final validPassword = StreamTransformer<String, String>.fromHandlers(
handleData: (password, sink){
if(password.length > 4){
sink.add(password);
}else{
sink.addError('Enter a valid password');
}
}
);
}
I want "invalid email" error to be displayed as this

Answer 1

Contains works perfectly for me.
void main() {
bool check;
String email = 'tes t#test.com';
check = email.contains(' ');
print(check); // true
}
I have tried it on DartPad
Perhaps you forgot to put whitespace between quotes.

Answer 2

Please don't use hand-rolled regex to validate email addresses. For one, spaces are in fact permitted in email addresses, as long as they are properly quoted, so the original question is already at fault. Also, these regex all reject many perfectly valid email addresses, such as my autoresponder at fred&barney#stonehenge.com. (Go ahead... send it email!)
If you're going to validate email, use https://pub.dev/packages/email_validator, which I have confirmed follows the proper rules.

Answer 3

The error you are having is the order in which you validate the email. You should first check for spaces and then for the # character.
handleData: (email, sink){
if(email.contains(" ")){
sink.addError('Enter a valid email');
} else if(email.contains('#')){
sink.add(email);
} else{
sink.addError('Enter a valid email');
}
}

Answer 4

You can also use a Regular Expression to validate an email address. Although, regular expressions are a bit complex to understand, they are very good for validating strings and checking patterns. Here's an example of a RegEx to validate an email address in Flutter/Dart
// String p to define pattern
String p = "[a-zA-Z0-9\+\.\_\%\-\+]{1,256}" +
"\\#" +
"[a-zA-Z0-9][a-zA-Z0-9\\-]{0,64}" +
"(" +
"\\." +
"[a-zA-Z0-9][a-zA-Z0-9\\-]{0,25}" +
")+";
//Convert string p to a RegEx
RegExp regExp = new RegExp(p);
//If email address matches pattern
if (regExp.hasMatch(emailAddress)) {
return 'Email is Valid';
}else{ //If it doesn't match
return 'Email is not valid';
}

Answer 5

The simplest solution to this is to call trim() on your email value before passing it. Something like this:
new AuthenticationService()
.signIn(_emailTextController.value.text.trim(),
_passwordTextController.value.text.trim())