pyforms - dynamic styling based on variable value

I am devloping a pyform control which only accept urls as input.

To achieve this I derivated my class from ControlText and added an keypress event handler which tests the current value against a regular expression.

Now i want to somehow change the controls appearance based on a variable like shown in style.css.

Controls.py

import pyforms
from   pyforms.Controls import ControlText
import re

class ControlUrl(ControlText):

    def __init__(self, label="", default=None, helptext=None, regex="^((https?:)?\/\/)?(\w+(:\w+)?@)?(((([a-zA-Z\d]{1,2}|[a-zA-Z\d][\w\-]{0,62}[a-zA-Z\d])\.){1,}[\w\-]{2,6})|(\d{1,3}(\.\d{1,3}){3})|([\d:]{2,39}))(:\d{2,6})?(\/[\w.~!+,*:@%-]+)*\/?(\?([\w.~!+%,*:@-]+(=[\w.~!+%,*:@-]+)?)(&[\w.~!+%,*:@-]+(=[\w.~!+%,*:@-]+)?)*)?(#[\w.~!+%,*:@-])?$"):
        self._regex = regex
        super(ControlUrl, self).__init__(label, default, helptext)

    def init_form(self):
        self._pattern = re.compile(self._regex)
        self.key_pressed_event = self.__key_pressed
        super(ControlUrl, self).init_form()

    def __key_pressed(self, event):
        is_url = self._pattern.search(self.value) != None
        self.valid = is_url

style.css

#_urlinput[valid="true"] {
    background-color: red;
}

I would prefer solving it with css but every solution is appreciated.

Solution

Dynamic styling is based on QPropertys which can be set with setProperty and the css selector looks like [propertyname=propertyvalue]

Code:

import sys
import pyforms
from   pyforms.Controls import ControlText
import re


class ControlUrl(ControlText):

    def __init__(self, *args, regex="^((https?:)?\/\/)?(\w+(:\w+)?@)?(((([a-zA-Z\d]{1,2}|[a-zA-Z\d][\w\-]{0,62}[a-zA-Z\d])\.){1,}[\w\-]{2,6})|(\d{1,3}(\.\d{1,3}){3})|([\d:]{2,39}))(:\d{2,6})?(\/[\w.~!+,*:@%-]+)*\/?(\?([\w.~!+%,*:@-]+(=[\w.~!+%,*:@-]+)?)(&[\w.~!+%,*:@-]+(=[\w.~!+%,*:@-]+)?)*)?(#[\w.~!+%,*:@-])?$", **kwargs):
        self._regex = regex
        super(ControlUrl, self).__init__(*args, **kwargs)

    def init_form(self):
        self._pattern = re.compile(self._regex)
        self.key_pressed_event = self.__key_pressed
        super(ControlUrl, self).init_form()

    def __key_pressed(self, event):
        self._valid = self._pattern.search(self.value) != None
        base = self.form.lineEdit
        base.setProperty("valid", self._valid)

        #without these lines the style is not applied
        base.style().unpolish(base)
        base.style().polish(base)

Css:

QLineEdit[valid=false] {
    border: 1px solid #991903;
    border-radius: 4px;
}
QLineEdit[valid=false]:focus {
    border-color: #db391c;
}

More Information: