Create a DB Browser style QHeaderview in PyQt5

Question

I would like to create a QHeaderView in PyQt5 like the one that is used in this project (DB Browser for SQLite). The problem is that I don't know C++ and I don't understand how the classes and widgets are created from the source code that is on GitHub. Does anybody how to emulate this filter header in python?

https://github.com/sqlitebrowser/sqlitebrowser/blob/master/src/FilterTableHeader.h

Answer 1

This is a very basic implementation of that approach.

The concept is to provide a correct sizeHint for the header (the default hint of the header plus the height of the line edit) and use setViewportMargins to ensure that the header has a bottom margin which is used by the text fields.

class Header(QtWidgets.QHeaderView):
    filterChanged = QtCore.pyqtSignal(int, str)
    fieldsVisible = True

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.fields = []
        self.sectionCountChanged.connect(self.generateFields)
        self.sectionResized.connect(self.updateFields)
        self.parent().horizontalScrollBar().valueChanged.connect(self.updateFields)
        self.parent().verticalScrollBar().valueChanged.connect(self.updateFields)

    def setFieldsVisible(self, visible):
        if visible == self.fieldsVisible:
            return
        self.fieldsVisible = visible
        self.generateFields()

    def generateFields(self):
        while self.fields:
            self.fields.pop().deleteLater()
        if self.fieldsVisible:
            for s in range(self.count()):
                edit = QtWidgets.QLineEdit(self)
                edit.show()
                self.fields.append(edit)
                edit.textChanged.connect(lambda text, s=s: self.filterChanged.emit(s, text))
            self.updateFields()
        self.updateGeometries()

    def updateFields(self):
        offset = self.offset()
        y = QtWidgets.QHeaderView.sizeHint(self).height()
        for section, field in enumerate(self.fields):
            field.move(self.sectionPosition(section) - offset, y)
            field.resize(self.sectionSize(section), field.sizeHint().height())

    def updateGeometries(self):
        if self.fields:
            self.setViewportMargins(0, 0, 0, self.fields[0].sizeHint().height())
        else:
            self.setViewportMargins(0, 0, 0, 0)
        super().updateGeometries()
        # ensure that the parent view updates correctly
        self.parent().updateGeometries()
        self.updateFields()

    def sizeHint(self):
        hint = super().sizeHint()
        if self.fields:
            hint.setHeight(hint.height() + self.fields[0].sizeHint().height())
        return hint


class SearchTable(QtWidgets.QTableView):
    def __init__(self):
        super().__init__()
        model = QtGui.QStandardItemModel()
        for row in range(8):
            model.appendRow([QtGui.QStandardItem('Item {} {}'.format(row, i)) for i in range(8)])
        self.setModel(model)
        self.setHorizontalHeader(Header(QtCore.Qt.Horizontal, self))

Note that this example does not take into account the possibility of moving sections, and if you want to implement a multi-column filter you'll need a subclass of QSortFilterProxyModel (for example, the one provided here). I provided a basic signal (filterChanged) which will return the section and the text changed.