How to save PySide tree view model structure

Question

Here is the link on other SO question QTreeView with custom items where is QTreeView example.

Please, can anyone explain me at this example, how to save tree structure from treeview.

1. Is the QAbstractItemModel class from which I can extract label names, and structure which I could load again?

2. If so, how could I access to nodes? Any other way except index?

EDIT (from the link) :

import sys
from PySide import QtGui, QtCore


#-------------------------------------------------------------------------------
# my test data
class Icon():
    def __init__(self, icon, tooltip):
        self.pixmap = QtGui.QPixmap(icon)
        self.tooltip = tooltip

#-------------------------------------------------------------------------------
# my test data
class MyData():
    def __init__(self, txt, parent=None):
        self.txt = txt
        self.tooltip = None
        self.parent = parent
        self.child = []
        self.icon = []
        self.index = None
        self.widget = None

    #---------------------------------------------------------------------------
    def position(self):
        position = 0
        if self.parent is not None:
            count = 0
            children = self.parent.child
            for child in children:
                if child == self:
                    position = count
                    break
                count += 1
        return position

    #---------------------------------------------------------------------------
    # test initialization
    @staticmethod
    def init():
        root = MyData("root")
        root.icon.append(Icon("icon.png", "ToolTip icon.png"))
        root.tooltip = "root tooltip"
        for i in range(0, 2):
            child1 = MyData("child %i" % (i), root)
            child1.icon.append(Icon("icon1.png", "ToolTip icon1.png"))
            child1.tooltip = "child1 tooltip"
            root.child.append(child1)
            for x in range(0, 2):
                child2 = MyData("child %i %i" % (i, x), child1)
                child2.icon.append(Icon("icon1.png", "ToolTip icon1.png"))
                child2.icon.append(Icon("icon2.png", "ToolTip icon2.png"))
                child2.tooltip = "child2 tooltip"
                child1.child.append(child2)

        return root

#-------------------------------------------------------------------------------
class TreeViewModel(QtCore.QAbstractItemModel):
    #---------------------------------------------------------------------------
    def __init__(self, tree):
        super(TreeViewModel, self).__init__()
        self.__tree = tree
        self.__current = tree
        self.__view = None

    #---------------------------------------------------------------------------
    def flags(self, index):
        flag = QtCore.Qt.ItemIsEnabled
        if index.isValid():
            flag |= QtCore.Qt.ItemIsSelectable \
                 | QtCore.Qt.ItemIsUserCheckable \
                 | QtCore.Qt.ItemIsEditable \
                 | QtCore.Qt.ItemIsDragEnabled \
                 | QtCore.Qt.ItemIsDropEnabled
        return flag

    #---------------------------------------------------------------------------
    def index(self, row, column, parent=QtCore.QModelIndex()):
        node = QtCore.QModelIndex()
        if parent.isValid():
            nodeS = parent.internalPointer()
            nodeX = nodeS.child[row]
            node = self.__createIndex(row, column, nodeX)
        else:
            node = self.__createIndex(row, column, self.__tree)
        return node

    #---------------------------------------------------------------------------
    def parent(self, index):
        node = QtCore.QModelIndex()
        if index.isValid():
            nodeS = index.internalPointer()
            parent = nodeS.parent
            if parent is not None:
                node = self.__createIndex(parent.position(), 0, parent)
        return node

    #---------------------------------------------------------------------------
    def rowCount(self, index=QtCore.QModelIndex()):
        count = 1
        node = index.internalPointer()
        if node is not None:
            count = len(node.child)
        return count

    #---------------------------------------------------------------------------
    def columnCount(self, index=QtCore.QModelIndex()):
        return 1

    #---------------------------------------------------------------------------
    def data(self, index, role=QtCore.Qt.DisplayRole):
        data = None
        return data

    #---------------------------------------------------------------------------
    def setView(self, view):
        self.__view = view

    #---------------------------------------------------------------------------
    def __createIndex(self, row, column, node):
        if node.index == None:
            index = self.createIndex(row, column, node)
            node.index = index
        if node.widget is None:
            node.widget = Widget(node)
            self.__view.setIndexWidget(index, node.widget)
        return node.index


#-------------------------------------------------------------------------------
class TreeView(QtGui.QTreeView):
    #---------------------------------------------------------------------------
    def __init__(self, model, parent=None):
        super(TreeView, self).__init__(parent)
        self.setModel(model)
        model.setView(self)
        root = model.index(0, 0)
        self.setCurrentIndex(root)
        self.setHeaderHidden(True)

    #---------------------------------------------------------------------------
    def keyPressEvent(self, event):
        k = event.key()
        if k == QtCore.Qt.Key_F2:
            self.__editMode()

        super(TreeView, self).keyPressEvent(event)

    #---------------------------------------------------------------------------
    def __editMode(self):
        index = self.currentIndex()
        node = index.internalPointer()
        node.widget.editMode(True, True)


#-------------------------------------------------------------------------------
class Label(QtGui.QLabel):
    #---------------------------------------------------------------------------
    def __init__(self, parent, text):
        super(Label, self).__init__(text)
        self.__parent = parent

    #---------------------------------------------------------------------------
    def mouseDoubleClickEvent(self, event):
        #print("mouseDoubleClickEvent")
        if self.__parent is not None:
            self.__parent.editMode(True, True)
        else:
            super(Label, self).mouseDoubleClickEvent(event)


#-------------------------------------------------------------------------------
class LineEdit(QtGui.QLineEdit):
    #---------------------------------------------------------------------------
    def __init__(self, parent, text):
        super(LineEdit, self).__init__(text)
        self.__parent = parent
        self.editingFinished.connect(self.__editingFinished)

    #---------------------------------------------------------------------------
    def keyPressEvent(self, event):
        k = event.key()
        if k == QtCore.Qt.Key_Escape:
            print("ESC 2")
            self.__editingFinished(False)
        super(LineEdit, self).keyPressEvent(event)

    #---------------------------------------------------------------------------
    def __editingFinished(self, bCopy=True):
        print("editingFinished")
        self.__parent.editMode(False, bCopy)

#-------------------------------------------------------------------------------
class Widget(QtGui.QWidget):
    #---------------------------------------------------------------------------
    def __init__(self, node):
        super(Widget, self).__init__()
        self.autoFillBackground()
        self.__node = node
        self.__bEditMode = False
        self.__txt = None
        self.__create(self.__node, self.__bEditMode)

    #---------------------------------------------------------------------------
    def __create(self, node, bEditMode):
        layout = QtGui.QHBoxLayout()
        for icon in node.icon:
            label = Label(None, node.txt)
            label.setPixmap(icon.pixmap)
            label.setToolTip("label tooltip %s %s" % (node.txt, icon.tooltip))
            layout.addWidget(label)

        self.__changeTxt(layout, node, bEditMode, False)
        self.setLayout(layout)

    #---------------------------------------------------------------------------
    def __changeTxt(self, layout, node, bEditMode, bCopy):
        if self.__txt is not None:
            if bCopy:
                node.txt = self.__txt.text()
            if isinstance(self.__txt, LineEdit):
                self.__txt.deselect()
            self.__txt.hide()
            layout.removeWidget(self.__txt)
            self.__txt = None

        if bEditMode:
            self.__txt = LineEdit(self, node.txt)
            self.__txt.setFrame(False)
            self.__txt.selectAll()
            QtCore.QTimer.singleShot(0, self.__txt, QtCore.SLOT('setFocus()'));
        else:
            self.__txt = Label(self, node.txt)
        self.__txt.setToolTip("Text tooltip %s %s" % (node.txt, node.tooltip))
        layout.addWidget(self.__txt, 1)

    #---------------------------------------------------------------------------
    def editMode(self, bEditMode, bCopy):
        if self.__bEditMode != bEditMode:
            self.__bEditMode = bEditMode
            layout = self.layout()
            self.__changeTxt(layout, self.__node, bEditMode, bCopy)

#-------------------------------------------------------------------------------
class MyTree(QtGui.QMainWindow):
    def __init__(self, parent=None):
        super(MyTree, self).__init__(parent)

        data = MyData.init()
        frame = QtGui.QFrame();
        frame.setLayout( QtGui.QHBoxLayout() );

        treeViewModel = TreeViewModel(data)
        treeView = TreeView(treeViewModel)
        frame.layout().addWidget( treeView );

        self.setCentralWidget(frame)

#-------------------------------------------------------------------------------
def main():
    app = QtGui.QApplication(sys.argv)
    form = MyTree()
    form.show()
    app.exec_()

if __name__ == '__main__':
    main()

Answer 1

Your question is quite unclear, because you don't say what form you want the tree structure saved in.

Assuming that you don't really care, and that XML would be acceptable, you could take a look at the Simple DOM Model Example from the Qt docs.

Most of the examples from the Qt docs have been ported to PyQt, and are provided with the source code, which can be downloaded from here. The Simple DOM Model example can be found under examples/itemviews.

EDIT:

I overlooked that you were using PySide. The equivalent ported examples for PySide can be found here, or in the PySide source code under sources/pyside-examples/examples/itemviews.

UPDATE:

Here's a simple example which uses xml.etree to serialize the tree:

import sip
sip.setapi('QString', 2)

from xml.etree import cElementTree as etree
from PyQt4 import QtGui, QtCore

class Window(QtGui.QWidget):
    def __init__(self, xml):
        QtGui.QWidget.__init__(self)
        self.tree = QtGui.QTreeWidget(self)
        self.tree.header().hide()
        self.importTree(xml)
        self.button = QtGui.QPushButton('Export', self)
        self.button.clicked[()].connect(self.exportTree)
        layout = QtGui.QVBoxLayout(self)
        layout.addWidget(self.tree)
        layout.addWidget(self.button)

    def importTree(self, xml):
        def build(item, root):
            for element in root.getchildren():
                child = QtGui.QTreeWidgetItem(
                    item, [element.attrib['text']])
                child.setFlags(
                    child.flags() | QtCore.Qt.ItemIsEditable)
                build(child, element)
            item.setExpanded(True)
        root = etree.fromstring(xml)
        build(self.tree.invisibleRootItem(), root)

    def exportTree(self):
        def build(item, root):
            for row in range(item.childCount()):
                child = item.child(row)
                element = etree.SubElement(
                    root, 'node', text=child.text(0))
                build(child, element)
        root = etree.Element('root')
        build(self.tree.invisibleRootItem(), root)
        from xml.dom import minidom
        print(minidom.parseString(etree.tostring(root)).toprettyxml())

if __name__ == '__main__':

    import sys
    app = QtGui.QApplication(sys.argv)
    window = Window("""\
<?xml version="1.0" ?>
<root>
    <node text="Child (0)">
        <node text="Child (0)">
            <node text="Child (0)"/>
            <node text="Child (1)"/>
        </node>
        <node text="Child (1)">
            <node text="Child (0)"/>
            <node text="Child (1)"/>
        </node>
    </node>
    <node text="Child (1)">
        <node text="Child (0)">
            <node text="Child (0)"/>
            <node text="Child (1)"/>
        </node>
        <node text="Child (1)">
            <node text="Child (0)"/>
            <node text="Child (1)"/>
        </node>
    </node>
</root>
        """)
    window.setGeometry(800, 300, 300, 300)
    window.show()
    sys.exit(app.exec_())