[FIXED] Overloaded "<" operator in QStandardItem, but it's not being called

Issue

I have a UI with a QTableView, which in turn uses the QStandardItemModel for its data. Because some of my data is numeric, I subclassed the QStandardItem to implement my own comparison. Per the docs, I only need to override the "<" operator (the __lt__(...) function). However, when I click the column header in the table view, the sort doesn't happen correctly. My model 'filler' is pretty simple:

self.model.removeRows(0, self.model.rowCount())
for i in range(0, len(self.mainFlatList)):
   self.model.setItem(i, 0, QStandardItem(self.mainFlatList[str(i)]["ID"]))
   self.model.setItem(i, 1, QStandardItem(self.mainFlatList[str(i)]["type"]))
   self.model.setItem(i, 2, QStandardItem(self.mainFlatList[str(i)]["string1"]))
   self.model.setItem(i, 3, QStandardItem(self.mainFlatList[str(i)]["string2"]))
   self.model.setItem(i, 4, QStandardItem(self.mainFlatList[str(i)]["timeva1"]))
   self.model.setItem(i, 5, QStandardItem(self.mainFlatList[str(i)]["timeval2"]))
   currentOPTimePercent = (float(self.mainFlatList[str(i)]["timeval1"])/self.totalTime) * 100
   self.mainFlatList[str(i)]["timePercent"] = currentOPTimePercent
   self.model.setItem(i, 6, MQStandardItem(str(self.mainFlatList[str(i)]["timePercent"])))

Where MQStandardItem is simply:

class MQStandardItem(QStandardItem):
def __init__(self, value):
    print "NumericalStandardItem", value
    QStandardItem.__init__(self, value)

def __lt__(self, obj):
    print "Sorting!"
    try:
        return float(self.text()) < float(obj.text())
    except:
        pass

    # Fallback to use standard __lt__
    return self.text() < obj.text()

Any ideas on why this could be failing? I should also note that the print statement in the __lt__(...) function doesn't even get printed, which leads me to wonder if I'm overriding things correctly. If it helps, here's how I construct the UI:

    self.model = QStandardItemModel(numRows,numColumns)
    self.model.setHorizontalHeaderItem(0, QStandardItem("ID"))
    self.model.setHorizontalHeaderItem(1, QStandardItem("Type"))
    self.model.setHorizontalHeaderItem(2, QStandardItem("string1"))
    self.model.setHorizontalHeaderItem(3, QStandardItem("string2"))
    self.model.setHorizontalHeaderItem(4, QStandardItem("timeval1"))
    self.model.setHorizontalHeaderItem(5, QStandardItem("timeval2"))
    self.model.setHorizontalHeaderItem(6, QStandardItem("timePercent"))

    self.tableView = QTableView()
    self.tableView.setModel(self.model)
    self.tableView.setSortingEnabled(True)
    self.tableView.setSelectionMode(QAbstractItemView.SingleSelection)
    self.tableView.setSelectionBehavior(QAbstractItemView.SelectRows)
    self.tableView.selectionModel().currentChanged.connect(self.foo)

Solution

All righty, it looks like this is a bug with Qt. There's an old post asking about this very issue:

http://www.qtcentre.org/threads/46985-any-solution-to-QtableView-sorting

and in looking through the source for the QTableView class, it seems that the connection between the view and model is still not made, at least from a look at:

http://qt.gitorious.org/qt/qt-gberg/blobs/90cdbf8bd409652fd1e28adcd7f02fc1fae2c1c0/src/gui/itemviews/qtableview.cpp (line 2280)

and

http://qt.gitorious.org/qt/qt/blobs/85f42777111060037476895ed08ded513d44a048/src/gui/itemviews/qstandarditemmodel.cpp (line 247)

The workaround is to use QTreeWidget, and still roll your own QTreeWidgetItem class for sorting. This works just fine.

Answered By - easythrees