how to Trim whitespace in textfield of flutter? - flutter

Question

I am using the below code for the email field along with the email validator in flutter application, which is working fine until if the user gives the whitespace after entering the email in the textfield, which I am not able to trim using .trim(), how should I trim the whitespace if in case the user has entered it?
String emailValidator(String value) {
Pattern pattern =
r'^(([^<>()[\]\\.,;:\s#\"]+(\.[^<>()[\]\\.,;:\s#\"]+)*)|(\".+\"))#((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$';
RegExp regex = new RegExp(pattern);
if (!regex.hasMatch(value)) {
return 'Email format is invalid';
} else {
return null;
}
}
final email = TextFormField(
decoration: InputDecoration(
labelText: "Email",
labelStyle: TextStyle(color: Colors.black),
prefixIcon: Icon(
LineIcons.envelope,
color: Colors.black38,
),
enabledBorder: UnderlineInputBorder(
borderSide: BorderSide(color: Colors.black38),
),
focusedBorder: UnderlineInputBorder(
borderSide: BorderSide(color: Colors.orange),
),
),
keyboardType: TextInputType.text,
style: TextStyle(color: Colors.black),
cursorColor: Colors.black,
controller: emailInputController,
validator: emailValidator,
);

Answer 1

For Flutter 1.20.0 and highest:
TextFormField(
validator: (value),
inputFormatters: [
FilteringTextInputFormatter.deny(new RegExp(r"\s\b|\b\s"))
],
)

Answer 2

How about you prevent user input whitespace using 'inputFormatters and BlacklistingTextInputFormatter'?
TextFormField(
validator: _validateInput,
inputFormatters: [BlacklistingTextInputFormatter(
new RegExp(r"\s\b|\b\s")
)],
...

Answer 3

It can be done in two different ways.
1.Allowing only the email regex.
inputFormatters: <TextInputFormatter>[
FilteringTextInputFormatter.allow(regex) // your email regex here
]
2.Denying the whitespace
inputFormatters: <TextInputFormatter>[
FilteringTextInputFormatter.allow(r"\s\b|\b\s")
]
Note: If you want to deny some special characters use FilteringTextInputFormatter.deny()
inputFormatters: <TextInputFormatter>[
FilteringTextInputFormatter.deny(regex) // your regex here
]

Answer 4

you should use inputFormatter and don't allow any white space.
TextFormField(
decoration: InputDecoration(
labelText: "Email",
labelStyle: TextStyle(color: Colors.black),
prefixIcon: Icon(
LineIcons.envelope,
color: Colors.black38,
),
enabledBorder: UnderlineInputBorder(
borderSide: BorderSide(color: Colors.black38),
),
focusedBorder: UnderlineInputBorder(
borderSide: BorderSide(color: Colors.orange),
),
),
keyboardType: TextInputType.text,
style: TextStyle(color: Colors.black),
cursorColor: Colors.black,
controller: emailInputController,
validator: emailValidator,
inputFormatters: [WhitelistingTextInputFormatter(RegExp(r'[a-zA-Z0-9]'))],
)