We Keep Coding

Concatenate Two QFileSystemModels

In this post, my goal is to concatenate two QFileSystemModels to one and display them together. (Lots of updates has been made)
Context :
In my C drive , I created the folder MyFolder (https://drive.google.com/drive/folders/1M-b2o9CiohXOgvjoZrAnl0iRVQBD1sXY?usp=sharing) , in which there are some folders and some files, for the sake of producing the minimal reproducible example . Their structure is :
The following Python code using PyQt5 library (modified from How to display parent directory in tree view?) runs after importing necessary libraries:
#The purpose of the proxy model is to display the directory.
#This proxy model is copied here from the reference without modification.
class ProxyModel(QSortFilterProxyModel):
def __init__(self, parent=None):
super().__init__(parent)
self._root_path = ""
def filterAcceptsRow(self, source_row, source_parent):
source_model = self.sourceModel()
if self._root_path and isinstance(source_model, QFileSystemModel):
root_index = source_model.index(self._root_path).parent()
if root_index == source_parent:
index = source_model.index(source_row, 0, source_parent)
return index.data(QFileSystemModel.FilePathRole) == self._root_path
return True
#property
def root_path(self):
return self._root_path
#root_path.setter
def root_path(self, p):
self._root_path = p
self.invalidateFilter()
class MainWindow(QMainWindow):
def __init__(self, parent=None):
super().__init__(parent)
self.create_treeview()
self.setCentralWidget(self.treeView_1) #The line I will be talking about.
def create_treeview(self):
self.treeView_1 = QTreeView()
self.dirModel_1 = QFileSystemModel()
self.dirModel_1.setRootPath(QDir.rootPath())
path_1 = 'C:/MyFolder/SubFolder1' # Changing the path is sufficient to change the displayed directory
root_index_1 = self.dirModel_1.index(path_1).parent()
self.proxy_1 = ProxyModel(self.dirModel_1)
self.proxy_1.setSourceModel(self.dirModel_1)
self.proxy_1.root_path = path_1
self.treeView_1.setModel(self.proxy_1)
proxy_root_index_1 = self.proxy_1.mapFromSource(root_index_1)
self.treeView_1.setRootIndex(proxy_root_index_1)
self.treeView_2 = QTreeView()
self.dirModel_2 = QFileSystemModel()
self.dirModel_2.setRootPath(QDir.rootPath())
path_2 = 'C:/MyFolder'
root_index_2 = self.dirModel_2.index(path_2).parent()
self.proxy_2 = ProxyModel(self.dirModel_2)
self.proxy_2.setSourceModel(self.dirModel_2)
self.proxy_2.root_path = path_2
self.treeView_2.setModel(self.proxy_2)
proxy_root_index_2 = self.proxy_2.mapFromSource(root_index_2)
self.treeView_2.setRootIndex(proxy_root_index_2)
if __name__ == "__main__":
import sys
app = QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
The line self.setCentralWidget(self.treeView_1) gives:
Changing self.setCentralWidget(self.treeView_1) to self.setCentralWidget(self.treeView_2) gives:
Objective:
My goal is to concatenate the two trees together. That is, when click run, the user should be able to see:
The order which they show up does not matter. All I care is that MyFolder and SubFolder1 show up as if they are completely independent items (even though in reality one is a subfolder of the other). I should remark that everything is static. That is, we are not trying to detect any changes on folders or files. The only time we ever need to peak at the existing folders and files will be when we click on run.
Update:
After several days of studying and trying, a major progress has been made. I thank musicamante for the hint of using QTreeWidget. The idea is, as said in comments, traverse through models and gradually move everything into one new QTreeWidget. To avoid freeze, my solution is to ask the QFileSystemModel to fetchMore whenever the user wants to see more (i.e. when the user wants to extend QTreeWidget).
The following code runs and almost solves my problem:
import os
from PyQt5.QtCore import*
from PyQt5.QtWidgets import*
from PyQt5 import QtTest
class To_Display_Folder(QSortFilterProxyModel):
def __init__(self, disables=False, parent=None):
super().__init__(parent)
#self.setFilterRegularExpression(r'^(.*\.dcm|[^.]+)$')
self._disables = bool(disables)
self._root_path = ""
def filterAcceptsRow(self, source_row, source_parent):
source_model = self.sourceModel()
#case 1 folder
if self._root_path and isinstance(source_model, QFileSystemModel):
root_index = source_model.index(self._root_path).parent()
if root_index == source_parent:
index = source_model.index(source_row, 0, source_parent)
return index.data(QFileSystemModel.FilePathRole) == self._root_path
return True
'''
#case 2 file
file_index = self.sourceModel().index(source_row, 0, source_parent)
if not self._disables:
return self.matchIndex(file_index)
return file_index.isValid()
'''
#property
def root_path(self):
return self._root_path
#root_path.setter
def root_path(self, p):
self._root_path = p
self.invalidateFilter()
def matchIndex(self, index):
return (self.sourceModel().isDir(index) or
super().filterAcceptsRow(index.row(), index.parent()))
def flags(self, index):
flags = super().flags(index)
if (self._disables and
not self.matchIndex(self.mapToSource(index))):
flags &= ~Qt.ItemIsEnabled
return flags
class Widget_Item_from_Proxy(QTreeWidgetItem):
def __init__(self, index_in_dirModel, parent = None):
super().__init__(parent)
self.setText(0, index_in_dirModel.data(QFileSystemModel.FileNameRole))
self.setText(1, index_in_dirModel.data(QFileSystemModel.FilePathRole))
if os.path.isfile(index_in_dirModel.data(QFileSystemModel.FilePathRole)):
self.setIcon(0,QApplication.style().standardIcon(QStyle.SP_FileIcon))
else:
self.setIcon(0,QApplication.style().standardIcon(QStyle.SP_DirIcon))
class MainWindow(QMainWindow):
def __init__(self, parent=None):
super().__init__(parent)
global treeWidget
treeWidget = QTreeWidget()
self.treeWidget = treeWidget
self.treeWidget.itemExpanded.connect(self.upon_expansion)
self.treeWidget.itemClicked.connect(self.tree_click)
#The following directories will be displayed on the tree.
self.add_path_to_tree_widget('C:/MyFolder')
self.add_path_to_tree_widget('C:/Users/r2d2w/OneDrive/Desktop')
self.add_path_to_tree_widget('C:/')
self.setCentralWidget(self.treeWidget)
def add_path_to_tree_widget(self,path):
dirModel = QFileSystemModel()
dirModel.setRootPath(QDir.rootPath())
dirModel.directoryLoaded.connect(lambda: self.once_loaded(path, dirModel))
def once_loaded(self, path, dirModel):
if dirModel.canFetchMore(dirModel.index(path)):
dirModel.fetchMore(dirModel.index(path))
return
root_index = dirModel.index(path).parent()
proxy = To_Display_Folder(disables = False, parent = dirModel)
proxy.setSourceModel(dirModel)
proxy.root_path = path
proxy_root_index = proxy.mapFromSource(root_index)
origin_in_proxy = proxy.index(0,0,parent = proxy_root_index)
root_item = Widget_Item_from_Proxy(
proxy.mapToSource(origin_in_proxy))
self.treeWidget.addTopLevelItem(root_item)
for row in range(0, proxy.rowCount(origin_in_proxy)):
proxy_index = proxy.index(row,0,parent = origin_in_proxy)
child = Widget_Item_from_Proxy(
proxy.mapToSource(proxy_index),
parent = self.treeWidget.topLevelItem(self.treeWidget.topLevelItemCount()-1))
dirModel.directoryLoaded.disconnect()
#pyqtSlot(QTreeWidgetItem)
def upon_expansion(self, treeitem):
for i in range(0, treeitem.childCount()):
if os.path.isdir(treeitem.child(i).text(1)):
self.add_child_path_to_tree_widget(treeitem.child(i))
def add_child_path_to_tree_widget(self,subfolder_item):
subfolder_path = subfolder_item.text(1)
dirModel = QFileSystemModel()
dirModel.setRootPath(QDir.rootPath())
dirModel.directoryLoaded.connect(lambda: self.child_once_loaded(subfolder_item, subfolder_path,dirModel))
def child_once_loaded(self, subfolder_item, subfolder_path, dirModel):
if dirModel.canFetchMore(dirModel.index(subfolder_path)):
dirModel.fetchMore(dirModel.index(subfolder_path))
return
root_index = dirModel.index(subfolder_path).parent()
proxy = To_Display_Folder(disables = False, parent = dirModel)
proxy.setSourceModel(dirModel)
proxy.root_path = subfolder_path
proxy_root_index = proxy.mapFromSource(root_index)
origin_in_proxy = proxy.index(0,0,parent = proxy_root_index)
root_item = Widget_Item_from_Proxy(
proxy.mapToSource(origin_in_proxy))
folder_item = subfolder_item.parent()
itemIndex = folder_item.indexOfChild(subfolder_item)
folder_item.removeChild(subfolder_item)
folder_item.insertChild(itemIndex, root_item)
for row in range(0, proxy.rowCount(origin_in_proxy)):
proxy_index = proxy.index(row,0,parent = origin_in_proxy)
child = Widget_Item_from_Proxy(
proxy.mapToSource(proxy_index),
parent = root_item)
dirModel.directoryLoaded.disconnect()
#pyqtSlot(QTreeWidgetItem)
def tree_click(self, item):
print(item.text(0))
print(item.text(1))
if __name__ == "__main__":
import sys
app = QApplication(sys.argv)
w = MainWindow()
w.show()
sys.exit(app.exec_())
Since the bounty period is still not over, I will use the time to post two new questions:
Sometimes, especially when the line self.add_path_to_tree_widget('C:/') is present, the code does not give all directories when we click run. This problem is easily fixed by closing the window and clicking on run again. This problem occurs because the QFileSystemModel does not yet have enough time to traverse through the designated folder. If it has just a little bit more time, it will be able to. I wonder if there is a way to fix this programatically.
The function add_path_to_tree_widget is similar to add_child_path_to_tree_widget. The function once_loaded is similar to child_once_loaded. I wonder if there is a way to write these functions more succinctly.

While not impossible, it's quite difficult to create a unique and dynamic model that is able to access different QFileSystemModel structures.
An easier and simpler implementation, which would be more practical for static purposes, is to use a QTreeWidget and create items recursively.
class MultiBrowser(QTreeWidget):
def __init__(self, *pathList):
super().__init__()
self.iconProvider = QFileIconProvider()
self.setHeaderLabels(['Name'])
for path in pathList:
item = self.createFSItem(QFileInfo(path), self.invisibleRootItem())
self.expand(self.indexFromItem(item))
def createFSItem(self, info, parent):
item = QTreeWidgetItem(parent, [info.fileName()])
item.setIcon(0, self.iconProvider.icon(info))
if info.isDir():
infoList = QDir(info.absoluteFilePath()).entryInfoList(
filters=QDir.AllEntries | QDir.NoDotAndDotDot,
sort=QDir.DirsFirst
)
for childInfo in infoList:
self.createFSItem(childInfo, item)
return item
# ...
multiBrowser = MultiBrowser('path1', 'path2')
For obvious reasons, the depth of each path and their contents will freeze the UI from interaction until the whole structure has been crawled.
If you need a more dynamic approach, consider using the QFileSystemModel as a source for path crawling, along with its directoryLoaded signal, which will obviously require a more complex implementation.

How to check correct opening the window after the click by button in pytest-qt

I want to test a module in my project, but I have a some problem with it. I don't know how I can check the correct opening of the window after the button click.
I have the windows SelectAddingBookTypeWindow and AddSchoolBookWindow.
I want to check that AddSchoolBookWindow will open after I have clicked on the button called selectBtn.
My current test (I have a problem with the last string because I don't know which method I must use):
#pytest.fixture
def open_window(qtbot):
def _press_button(window):
widget = window()
qtbot.addWidget(widget)
widget.show()
qtbot.wait_for_window_shown(widget)
sleep(3)
return widget
return _press_button
class TestSelectAddingBookTypeWindow:
def test_select_schoolbook(self, open_window, qtbot):
widget = open_window(SelectAddingBookTypeWindow)
qtbot.mouseClick(widget.schoolbookSelector, QtCore.Qt.LeftButton)
qtbot.mouseClick(widget.selectBtn, QtCore.Qt.LeftButton)
assert widget.close()
assert AddSchoolBookWindow.isActiveWindow()
My classes:
A. SelectAddingBookTypeWindow
class SelectBookTypeWindow(QDialog, Ui_selectBookTypeWindow):
#logger.catch
def __init__(self, widget1, widget2):
super().__init__()
self.setupUi(self)
self.selectBtn.clicked.connect(lambda x: self.open_new_window(widget1, widget2))
#logger.catch
def open_new_window(self, schoolbook_widget, fictionbook_widget):
if self.schoolbookSelector.isChecked():
widget = schoolbook_widget()
elif self.fictionbookSelector.isChecked():
widget = fictionbook_widget()
widget.show()
self.close()
class SelectAddingBookTypeWindow(SelectBookTypeWindow):
#logger.catch
def __init__(self):
super().__init__(AddSchoolBookWindow, AddFictionBookWindow)
B. AddSchoolBookWindow
class AddSchoolBookWindow(QDialog, Ui_AddSchoolbookWindow):
#logger.catch
def __init__(self):
super().__init__()
self.setupUi(self)
self.widgets = [
self.schoolbookAuthor, self.schoolbookTitle, self.schoolbookPublishHouse,
self.schoolbookPublishYear, self.schoolbookInvoiceNum, self.schoolbookInvoiceDate, self.schoolbookClass,
self.schoolbookCount, self.schoolbookPrice
]
self.schoolbookSaveBtn.clicked.connect(lambda _: self.save_book())
self.schoolbookClearBtn.clicked.connect(lambda _: Utils.clear_fields(self.widgets, self.schoolbookInvoiceDate))
self.schoolbookCancelBtn.clicked.connect(lambda _: self.close())
#logger.catch
def save_book(self):
field_names = Config.COLUMNS['SchoolBook']
user_data = list(map(lambda x: x.text(), self.widgets))
book_sum = Utils.calculate_book_sum(user_data)
user_data.append(str(book_sum))
book = dict(zip(field_names[1:], user_data))
db = DatabaseManager(Config.PATHES['TO_DATABASE']['PROD'])
model = Schoolbook('SchoolBook', db.connection)
model.insert_book(book)
logger.success(f'The {book} success add in the database')
model.model.select()
This is a little part of full code but full code doesn't solve with this problem.

The problem in your case is that the widget is not accessible since it is a local variable, I also doubt that the window will be shown as it should be removed a moment later, so to access it I will create a property:
class SelectBookTypeWindow(QtWidgets.QDialog, Ui_selectBookTypeWindow):
def __init__(self, widget1, widget2):
super().__init__()
self.setupUi(self)
self.selectBtn.clicked.connect(lambda x: self.open_new_window(widget1, widget2))
self._selected_window = None
#property
def selected_window(self):
return self._selected_window
def open_new_window(self, schoolbook_widget, fictionbook_widget):
if self.schoolbookSelector.isChecked():
self._selected_window = schoolbook_widget()
elif self.fictionbookSelector.isChecked():
self._selected_window = fictionbook_widget()
if self.selected_window is not None:
self.selected_window.show()
self.close()
And then in the test you should verify that selected_window is not None and its base class is AddSchoolBookWindow, also avoid using time.sleep(), in the case of the tests use QTest.qWait()
import pytest
from PyQt5 import QtCore, QtTest
from your_package import AddSchoolBookWindow, SelectAddingBookTypeWindow
#pytest.fixture
def open_window(qtbot):
def callback(window):
widget = window()
qtbot.addWidget(widget)
widget.show()
qtbot.wait_for_window_shown(widget)
QtTest.QTest.qWait(3 * 1000)
return widget
return callback
class TestSelectAddingBookTypeWindow:
def test_select_schoolbook(self, open_window, qtbot):
widget = open_window(SelectAddingBookTypeWindow)
assert widget.isVisible()
qtbot.mouseClick(widget.schoolbookSelector, QtCore.Qt.LeftButton)
qtbot.mouseClick(widget.selectBtn, QtCore.Qt.LeftButton)
assert widget.isHidden()
assert widget.selected_window is not None
assert isinstance(widget.selected_window, AddSchoolBookWindow)
assert widget.selected_window.isVisible()

PyQt4 How to send push button signal to another class in Python?

I need your advice and help for my code.
I am making a GUI program. Basically the program does the followings:
Gets input from the user
When a certain button is pushed, the program retrieves all the input and saved them in the database
The program does computations.
Shows the output
Here is the simple version of the program, calculator program:
As you can see in the figure, it takes 4 input from user, (1) any integer for var1, (2) any integer for var2, (3) operator (addition or subtraction) and (4) click button.
The GUI was designed using QtDesigner.
And here is my code:
import sys
import sqlite3
from PyQt4 import QtCore, QtGui
from testgui import Ui_MainWindow
class ShowAndInput(QtGui.QMainWindow):
def __init__(self, parent=None):
QtGui.QWidget.__init__(self, parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
#connect to the database
self.connect_to_db()
#create table in the database
self.create_table()
#add items to the comboBox
self.add_items()
#calculate button to start calculating, gives signal to the next class Calculate
self.ui.pushButton_3.clicked.connect(self.calculate)
#close button to close the window
QtCore.QObject.connect(self.ui.pushButton,QtCore.SIGNAL("clicked()"), quit)
self.conn.close()
def connect_to_db(self):
self.conn = sqlite3.connect('testguidb.sqlite3')
self.cur = self.conn.cursor()
def create_table(self):
self.cur.execute('''CREATE TABLE IF NOT EXISTS Input (var1 INTEGER, var2 INTEGER)''')
self.conn.commit()
def add_items(self):
lst = ['addition', 'subtraction']
self.ui.comboBox.clear()
self.ui.comboBox.addItems(lst)
def calculate(self):
calculate = Calculate(self)
calculate.exec_()
So the purpose of the first class was to show the GUI and take input from the user. If user clicks the pushbutton named 'Calculate', it should connect to the new class named 'Calculate'.
Here is my code for the Calculate class:
class Calculate(QtGui.QMainWindow):
def __init__(self, parent = None):
QtGui.QWidget.__init__(parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
#validator to validate that the input is integer or digit
#connect to database
self.connect_to_db()
#get the input values and store them in the database
self.get_the_values()
#print the output
PrintOutcome()
def connect_to_db(self):
self.conn = sqlite3.connect('testguidb.sqlite3')
self.cur = self.conn.cursor()
def get_the_values(self):
dicti = {}
dicti['var1'] = self.ui.lineEdit.text()
dicti['var2'] = self.ui.lineEdit_2.text()
for key, val in sorted(dicti.items()):
key = str(key)
val = int(val)
self.cur.execute('INSERT OR IGNORE INTO Input (?) VALUES (?)',(key,val))
self.conn.commit()
And at the end of this class, it calls another class named 'PrintOutcome' to print out the result in the QTextBrowser. Here is the last piece of the code:
class PrintOutcome(QtGui.QMainWindow):
def __init__(self, parent = None):
QtGui.QWidget.__init__(parent)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
#connect to database
self.connect_to_db()
#get the value of the combobox
self.get_combox()
#print the output
if self.operator == 'addition': self.print_add()
elif self.operator == 'subtraction': self.print_sub()
def connect_to_db(self):
self.conn = sqlite3.connect('testguidb.sqlite3')
self.cur = self.conn.cursor()
def get_combox(self):
self.operator = str(self.ui.comboBox.currentText())
def print_add(self):
dicti={}
for i in range(2):
i = i + 1
dicti['var{0}'.format(i)] = self.cur.execute('SELECT var{0} FROM Input'.format(i))
dicti['var{0}'.format(i)] = int(self.cur.fetchone()[0])
text = str(dicti['var{0}'.format(i)])
self.ui.textBrowser.append(text)
result = dicti['var1'] + dicti['var2']
textsep = '-'*25+'(+)'
text = str(result)
self.ui.textBrowser.append(text)
self.ui.textBrowser.append(text)
def print_sub(self):
dicti={}
for i in range(2):
i = i + 1
dicti['var{0}'.format(i)] = self.cur.execute('SELECT var{0} FROM Input'.format(i))
dicti['var{0}'.format(i)] = int(self.cur.fetchone()[0])
text = str(dicti['var{0}'.format(i)])
self.ui.textBrowser.append(text)
result = dicti['var1'] + dicti['var2']
textsep = '-'*25+'(-)'
text = str(result)
self.ui.textBrowser.append(text)
self.ui.textBrowser.append(text)
if __name__=='__main__':
app = QtGui.QApplication(sys.argv)
myapp = ShowAndInput()
myapp.show()
sys.exit(app.exec_())
When I ran it, everything was fine. But when I pressed the calculate button, it returned an error message.
Here is the error message: RuntimeError: super-class init() of type Calculate was never called.
Any respond will be much appreciated. Thanks a lot.
Regards,
Arnold

PyGI emulating set_attribute / appropriate signal to emit?

I have an existing project that I'm trying to build a GUI around (using PyGI + Gtk3). There are some native objects that I need to extend slightly to make them renderable. I've boiled the problem down to the simplified code here:
# Simplified Equivalent Code
from gi.repository import GObject
from gi.repository import Gtk
from gi.repository import GdkPixbuf
# Pre-existing, complex object
class Move(object):
def __init__(self, color):
self.color = color
# Pre-existing, complex object
class Block(object):
def __init__(self,move=None,**kwds):
self.move = move
# New object created to help render a Block
class BlockGui(Block):
pixbufs = {
'empty' : GdkPixbuf.Pixbuf.new_from_file('block_empty.png'),
'red' : GdkPixbuf.Pixbuf.new_from_file('block_red.png'),
'blue' : GdkPixbuf.Pixbuf.new_from_file('block_blue.png'),
}
def __setattr__(self, name, value):
super(BlockGui, self).__setattr__(name, value)
if name == 'move':
print "Need to emit a signal here"
def get_pixbuf(self):
try:
return BlockGui.pixbufs[self.move.color]
except AttributeError:
return BlockGui.pixbufs['empty']
class BlockRenderer(Gtk.CellRendererPixbuf):
__gproperties__ = {
'block' : (GObject.TYPE_PYOBJECT,
'block to render',
'the block object to be rendered',
GObject.PARAM_READWRITE)
}
def __init__(self):
GObject.GObject.__init__(self)
self.block = None
def do_set_property(self, prop, value):
# What is a GParamBoxed? Should I be checking if prop == 'block' from it somehow?
if isinstance(value, BlockGui):
self.block = value
self.set_property('pixbuf', self.block.get_pixbuf())
GObject.type_register(BlockRenderer)
def destroy(widget, data=None):
Gtk.main_quit()
# Normally do not have access to this assignment
def on_clicked(widget, liststore, treeview):
treeiter = liststore.get_iter(2)
block = liststore.get_value(treeiter, 1)
block.move = Move('red')
def main():
# 3x5 so this demo window has some size
fmt = [GObject.TYPE_PYOBJECT] * 3
liststore = Gtk.ListStore(*fmt)
for r in xrange(5):
liststore.append([BlockGui() for x in xrange(3)])
treeview = Gtk.TreeView(liststore)
for c in xrange(3):
col = Gtk.TreeViewColumn(str(c))
treeview.append_column(col)
cell = BlockRenderer()
col.pack_start(cell, True)
col.add_attribute(cell, 'block', c)
button = Gtk.Button("Change Color!")
button.connect('clicked', on_clicked, liststore, treeview)
vbox = Gtk.VBox()
vbox.add(treeview)
vbox.add(button)
window = Gtk.Window(Gtk.WindowType.TOPLEVEL)
window.connect('destroy', destroy)
window.add(vbox)
window.show_all()
Gtk.main()
if __name__ == '__main__':
main()
When the current code is run, clicking the button yields no immediate result, but running the mouse over the changed row will cause the center square to turn red (as the hover over the row triggers a refresh). Normally, when a 'proper' GObject has a set_attribute called, it will emit some signals to notify the widgets containing it to re-render.
I need to know which signal that emits, to whom it's emitted, and how to emulate that behavior.

If you know the widget that must be redrawn, then you can just call queue_draw(), queue_draw_region() or queue_draw_area() for that widget. That will invalidate that window area and it will be redrawn. If you want more fine grained control, you might want to use Gtk.DrawingArea.
You might want to check the documentation for The GTK+ Drawing Model.

Differentiating between signal sources in PySide

Is there trivial or elegant way to differentiate between many same-type signal sources in PySide/PyQt?
I am learning PySide. I have written simple application, which multiplies two numbers from two different QLineEdit() objects. Result is displayed in third QLineEdit.
Multiplier and multiplicand QLineEdit.textChanged() signals are connected to one method (TxtChanged). In this method i have to differentiate between signal sources. After some trials I figured out some workaround based upon placeholder text (4 lines below "is there another way?" comment in my code)
code:
import sys
from PySide import QtGui, QtCore
class myGUI(QtGui.QWidget):
def __init__(self, *args, **kwargs):
QtGui.QWidget.__init__(self, *args, **kwargs)
self.multiplier = 0
self.multiplicand = 0
self.myGUIInit()
def myGUIInit(self):
# input forms
a1_label = QtGui.QLabel("a1")
a1_edit = QtGui.QLineEdit()
a1_edit.setPlaceholderText("a1")
a2_label = QtGui.QLabel("a2")
a2_edit = QtGui.QLineEdit()
a2_edit.setPlaceholderText("a2")
# output form
a1a2_label = QtGui.QLabel("a1*a2")
self.a1a2_edit = QtGui.QLineEdit()
self.a1a2_edit.setReadOnly(True)
# forms events
a1_edit.textChanged.connect(self.TxtChanged)
a2_edit.textChanged.connect(self.TxtChanged)
# grid
grid = QtGui.QGridLayout()
grid.setSpacing(10)
grid.addWidget(a1_label,1,0)
grid.addWidget(a1_edit,1,1)
grid.addWidget(a2_label,2,0)
grid.addWidget(a2_edit,2,1)
grid.addWidget(a1a2_label,3,0)
grid.addWidget(self.a1a2_edit,3,1)
self.setLayout(grid)
self.setGeometry(100,100,200,200)
self.setWindowTitle("a*b")
self.show()
def TxtChanged(self,text):
sender = self.sender()
sender_text = sender.text()
if sender_text == '': sender_text = '0'
# is there another way?
if sender.placeholderText() == 'a1':
self.multiplicand = sender_text
else:
self.multiplier = sender_text
product = int(self.multiplier) * int(self.multiplicand)
print(self.multiplier,self.multiplicand,product)
self.a1a2_edit.setText(str(product))
def main():
app = QtGui.QApplication(sys.argv)
mainWindow = myGUI()
sys.exit(app.exec_())
main()
best regards,
ostrzysz

You can use the functools.partial function - and therefore connect your signals to straight to your method/function but rather to a python object which will automatically call your function with some extra data you pass it:
from functools import partial
...
....
a1_edit.textChanged.connect(partial(self.TxtChanged, a1_edit))
a2_edit.textChanged.connect(partial(self.TxtChanged, a2_edit))
...
def TxtChanged(self,sender, text):
# and here you have the "sender" parameter as it was filled in the call to "partial"
...
partials is part of the stdlib, and is very readable, but one can always use lambda instead of partial for the same effect -
a1_edit.textChanged.connect(lambda text: self.TxtChanged(a1_edit, text))
In this way the object yielded by the lambda expression will be a temporary function that will use the values for "self" and "a1_edit" from the current local variables (at the time the button is clicked), and the variable named "text" will be supplied by Pyside's callback.

One thing that bugs me most in your code is that you are using placeholderText to differentiate. QObjects has another property called objectName that is more suitable for your task. And, you don't need to use sender.text() to get the text of QLineEdit. textChanged already sends it, so you will have it in your text parameter.
Also, using a dictionary instead of two separate variables (multiplier and multiplicand) will simplify your code further.
Here is the changed code:
class myGUI(QtGui.QWidget):
def __init__(self, *args, **kwargs):
QtGui.QWidget.__init__(self, *args, **kwargs)
self.data = {"multiplier": 0,
"multiplicand": 0}
self.myGUIInit()
def myGUIInit(self):
a1_label = QtGui.QLabel("a1")
a1_edit = QtGui.QLineEdit()
a1_edit.setObjectName("multiplicand")
a2_label = QtGui.QLabel("a2")
a2_edit = QtGui.QLineEdit()
a2_edit.setObjectName("multiplier")
# skipped the rest because same
def TxtChanged(self, text):
sender = self.sender()
# casting to int while assigning seems logical.
self.data[sender.objectName()] = int(text)
product = self.data["multiplier"] * self.data["multiplicand"]
print(self.data["multiplier"], self.data["multiplicand"], product)
self.a1a2_edit.setText(str(product))

Although #jsbueno and #Avaris answered your direct question about signal sources, I wouldn't relay on this sources in your concrete case. You can make instance members a1_edit and a2_edit:
...
self.a1_edit = QtGui.QLineEdit()
...
self.a2_edit = QtGui.QLineEdit()
...
It will simplify your TxtChanged function:
def TxtChanged(self,text):
try:
multiplier = int(self.a1_edit.text())
multiplicand = int(self.a2_edit.text())
except ValueError:
self.a1a2_edit.setText('Enter two numbers')
return
product = multiplier * multiplicand
print(multiplier, multiplicand, product)
self.a1a2_edit.setText(str(product))
Also, instead of handling ValueError exception, you can use QIntValidator for input controls:
self.int_validator = QtGui.QIntValidator()
self.a1_edit.setValidator(self.int_validator)
self.a2_edit.setValidator(self.int_validator)