Many peoples validate the Form for numbers using the property/widget of TextFormField() widget like keyboardType: TextInputType.number But I have a question that can we validate the Form only to prevent the Alphabets and punctuation marks from the Form and keeps the text of FormFiled String (numbers) ? is It possible ? If you have any logic for this please share it.

CodePudding user response：

TextField had inputFormatter. Just add this line inside the text field widget

  inputFormatters: <TextInputFormatter>. 
          [WhitelistingTextInputFormatter.digitsOnly], // Only numbers are allowed

CodePudding user response：

Even if the keyboardType property is set to TextInputType.phone the text of the form field will be string and not num. For further validation, use the validator property.