PyQt: Adding rows to QTableView using QAbstractTableModel

Question

I am super new to Qt programming. I am trying to make a simple table that can have rows added by clicking a button. I can implement the table fine but can't seem to get the updated data to show on the table. I believe my problem stems from the fact that I can't seem to properly call any sort of "change data" method using the button. I've tried several different solutions online all of which have lead to 4 year old, dead-end posts. What I have so far is the basic structure, I just can't figure out how to make the table update with new data.

This is the basic view

I have set up with some test data.

In the final implementation, the table will start empty and I would like to append rows and have them displayed in the table view.

import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *

class MyWindow(QWidget):
    def __init__(self):
        QWidget.__init__(self)

        # create table
        self.get_table_data()
        self.table = self.createTable()

        # layout
        self.layout = QVBoxLayout()

        self.testButton = QPushButton("test")
        self.connect(self.testButton, SIGNAL("released()"), self.test)        

        self.layout.addWidget(self.testButton)
        self.layout.addWidget(self.table)
        self.setLayout(self.layout)

    def get_table_data(self):
        self.tabledata = [[1234567890,2,3,4,5],
                          [6,7,8,9,10],
                          [11,12,13,14,15],
                          [16,17,18,19,20]]

    def createTable(self):
        # create the view
        tv = QTableView()

        # set the table model
        header = ['col_0', 'col_1', 'col_2', 'col_3', 'col_4']
        tablemodel = MyTableModel(self.tabledata, header, self)
        tv.setModel(tablemodel)

        # set the minimum size
        tv.setMinimumSize(400, 300)

        # hide grid
        tv.setShowGrid(False)

        # hide vertical header
        vh = tv.verticalHeader()
        vh.setVisible(False)

        # set horizontal header properties
        hh = tv.horizontalHeader()
        hh.setStretchLastSection(True)

        # set column width to fit contents
        tv.resizeColumnsToContents()

        # set row height
        tv.resizeRowsToContents()

        # enable sorting
        tv.setSortingEnabled(False)

        return tv

    def test(self):
        self.tabledata.append([1,1,1,1,1])
        self.emit(SIGNAL('dataChanged()'))
        print 'success'

class MyTableModel(QAbstractTableModel):
    def __init__(self, datain, headerdata, parent=None):
        """
        Args:
            datain: a list of lists\n
            headerdata: a list of strings
        """
        QAbstractTableModel.__init__(self, parent)
        self.arraydata = datain
        self.headerdata = headerdata

    def rowCount(self, parent):
        return len(self.arraydata)

    def columnCount(self, parent):
        if len(self.arraydata) > 0: 
            return len(self.arraydata[0]) 
        return 0

    def data(self, index, role):
        if not index.isValid():
            return QVariant()
        elif role != Qt.DisplayRole:
            return QVariant()
        return QVariant(self.arraydata[index.row()][index.column()])

    def setData(self, index, value, role):
        pass         # not sure what to put here

    def headerData(self, col, orientation, role):
        if orientation == Qt.Horizontal and role == Qt.DisplayRole:
            return QVariant(self.headerdata[col])
        return QVariant()

    def sort(self, Ncol, order):
        """
        Sort table by given column number.
        """
        self.emit(SIGNAL("layoutAboutToBeChanged()"))
        self.arraydata = sorted(self.arraydata, key=operator.itemgetter(Ncol))       
        if order == Qt.DescendingOrder:
            self.arraydata.reverse()
        self.emit(SIGNAL("layoutChanged()"))

if __name__ == "__main__":
    app = QApplication(sys.argv)
    w = MyWindow()
    w.show()
    sys.exit(app.exec_())

Acerose

Agree.. The code sample in your question is an answer to many other question. – Irreducible

Answer 1

When the underlying data of the model changes, the model should emit either layoutChanged or layoutAboutToBeChanged, so that view updates properly (there's also dataChanged, if you want to update a specific range of cells).

So you just need something like this:

    def test(self):
        self.tabledata.append([1,1,1,1,1])
        self.table.model().layoutChanged.emit()
        print 'success'

Brei

Wouldn't setData() be needed as well in the model? I've looked through all the documentation and I keep seeing references to needing to have either setData() or insertRows(), etc. Problem is I'm not 100% sure how to implement the setData() method or more importantly how to call it. - EDIT: Well I just tried your edit and it worked perfectly without the setData() method so I guess it isn't needed after all! I really appreciate the help! – Acerose

Usually you need to implement setData() when you want an editable grid, in order to update the correct value in your model. For example: def setData(self, index, value, role = Qt.EditRole): if role == Qt.EditRole: setattr(self.arraydata[index.row()], self.columns[index.column()], value) self.dataChanged.emit(index, index, ()) return True else: return False – Preceptor

Technically this wouldn't work, because self.tabledata is just a list and is not really connected to the QTableView. – Losel

Answer 2

QAbstractTableModel have two special methods for that ( beginInsertRows() and endInsertRows()).

You can add api-point in your custom model. For example:

    def insertGuest(self, guest):
        self.beginInsertRows(QtCore.QModelIndex(), self.rowCount(), self.rowCount())
        self.guestsTableData.append(guest)
        self.endInsertRows()

Pecan

I think this is the better solution since a layoutChanged signal likely causes a redraw or at least reevaluation of the entire view. While begin/endInstertRows is a more subtle way to notify the visuals that a new row has been added and its location. If the row added is not in the current view, then it can be ignored (or just scrollbars updated/redrawn) – Filigreed

Answer 3

I've made your table reference a class variable instead of an instance variable, so you could edit the data for the table from virtually anywhere in your code.

# First access the data of the table
self.tv_model = self.tv.model()

Secondly, I use the sort of pandas-dataframe-editing type approach. Lets say your data that you want to add is stored in a variable on its own:

# These can be whatever, but for consistency, 
# I used the data in the OP's example

new_values = [1, 1, 1, 1, 1]

There are different ways the next step can be approached, depending on whether the data is being added to the table, or updating existing values. Adding the data as a new row would be as follows.

# The headers should also be a class variable, 
# but I left it as the OP had it

header = ['col_0', 'col_1', 'col_2', 'col_3', 'col_4']

# There are multiple ways of establishing what the row reference should be,
# this is just one example how to add a new row

new_row = len(self.tv_model.dataFrame.index)

for i, col in enumerate(header):
    self.tv_model.dataFrame.loc[new_row, col] = new_values[i]

Since self.tv_model is a reference to the actual data of the table, emitting the following signal will update the data, or 'commit' it to the model, so to speak.

self.tv_model.layoutChanged.emit()

Losel