带有 QValidator 的 PyQt QLineEdit

Question

I have a QLineEdit in my project. I want to use the QValidation on lineEdit.

#Create lineEdit
itemValue = QtWidgets.QLineEdit()
#Create валидатор
objValidator = QtGui.QDoubleValidator(self)
#setup range
objValidator.setRange(-10.0, 100.0, 5)
#lineEdit with validation
itemValue.setValidator(objValidator)

But it doesn't work well.I can type what i want, except symbols. And range doesn't work!I can type 100500 or -100500, but i want, that user can enter numbers only in range.

How i should use range? I need help:)

Thanks for your help, guys!

Answer 1

By default, a validator will not prevent values outside the range from being entered, and it won't prevent the user leaving the line-edit if the entered value is Invalid or Intermediate .

However, it does give you an opportunity to reject the input programmatically, because whenever the current value is unacceptable, the line-edit won't emit itseditingFinished or returnPressed signals, and its hasAcceptableInput method will return False . In addition, if you subclass the validator, you can reimplement its fixup method to control the values that are entered.

However, as has been suggested already, a far better/simpler solution is to use a QDoubleSpinBox , since it cleans up the input automatically and provides a more user-friendly interface.

Answer 2

As an alternative you could use a QDoubleSpinBox .

• has validator build in
• prevents invalid input while typing
• has build-in setRange()
• and adds a little handle to change the value for more mouse oriented users.

Answer 3

Probably you are expecting something what should not happen.
In general when you have validator you should be able to type something in intermediate state what doesn't exactly meet limitation. But this should be fixed, when editor looses focus.

Why? Imagine you have 84 an you want correct this to -8.4 . Many people will do this like that: add minus so now you have -84 which is not acceptable then add dot. If validator fixes this immediately it would be annoying for user.

So bottom line does this "problem" happen when editor looses focus?