example.py

class IndicatorLineEdit(QWidget):
    def __init__(self,
                 text: str = "",
                 edit_func: Callable[[str], bool] = None,
                 save_func: Callable[[str], None] = None,
                 horiz_policy: QSizePolicy = QSizePolicy.Expanding,
                 parent=None):
        super(IndicatorLineEdit, self).__init__(parent=parent)
        self.setObjectName("IndicatorTextEdit")
        self.layout = QHBoxLayout(self)
        self.layout.setObjectName("layout")
        self.layout.setContentsMargins(0, 0, 0, 0)
        self.line_edit = QLineEdit(self)
        self.line_edit.setObjectName("line_edit")
        self.line_edit.setSizePolicy(horiz_policy, QSizePolicy.Fixed)
        self.layout.addWidget(self.line_edit)
        if edit_func is not None:
            self.indicator_label = QLabel()
            self.indicator_label.setPixmap(icon("ei.info-circle", color="gray").pixmap(16, 16))
            self.indicator_label.setSizePolicy(QSizePolicy.Fixed, QSizePolicy.Fixed)
            self.layout.addWidget(self.indicator_label)

        _translate = QCoreApplication.translate
        self.line_edit.setPlaceholderText(_translate("PathEdit", "Default"))

        if text:
            self.line_edit.setText(text)

        self.edit_func = edit_func
        self.save_func = save_func
        self.line_edit.textChanged.connect(self.__edit)
        if self.edit_func is None:
            self.line_edit.textChanged.connect(self.__save)

    def text(self):
        return self.line_edit.text()

    def setText(self, text: str):
        self.line_edit.setText(text)

    def setPlaceholderText(self, text: str):
        self.line_edit.setPlaceholderText(text)

    def __indicator(self, res):
        color = "green" if res else "red"
        self.indicator_label.setPixmap(icon("ei.info-circle", color=color).pixmap(16, 16))

    def __edit(self, text):
        if self.edit_func is not None:
            res = self.edit_func(text)
            self.__indicator(res)
            if res:
                self.__save(text)

    def __save(self, text):
        if self.save_func is not None:
            self.save_func(text)


class PathEdit(IndicatorLineEdit):
    def __init__(self,
                 text: str = "",
                 file_type: QFileDialog.FileType = QFileDialog.AnyFile,
                 type_filter: str = "",
                 name_filter: str = "",
                 edit_func: Callable[[str], bool] = None,
                 save_func: Callable[[str], None] = None,
                 horiz_policy: QSizePolicy = QSizePolicy.Expanding,
                 parent=None):
        super(PathEdit, self).__init__(text=text,
                                       edit_func=edit_func,
                                       save_func=save_func,
                                       horiz_policy=horiz_policy,
                                       parent=parent)
        self.setObjectName("PathEdit")
        self.path_select = QToolButton(self)
        self.path_select.setObjectName("path_select")
        self.layout.addWidget(self.path_select)

        _translate = QCoreApplication.translate
        self.path_select.setText(_translate("PathEdit", "Browse..."))

        self.type_filter = type_filter
        self.name_filter = name_filter
        self.file_type = file_type

        self.path_select.clicked.connect(self.__set_path)

    def __set_path(self):
        dlg_path = self.line_edit.text()
        if not dlg_path:
            dlg_path = os.path.expanduser("~/")
        dlg = QFileDialog(self, self.tr("Choose path"), dlg_path)
        dlg.setFileMode(self.file_type)
        if self.type_filter:
            dlg.setFilter([self.type_filter])
        if self.name_filter:
            dlg.setNameFilter(self.name_filter)
        if dlg.exec_():
            names = dlg.selectedFiles()
            self.line_edit.setText(names[0])