Myujth

This is a follow-up to this question. In there, we created an editable subclass of QSqlQueryModel, to use with complex queries.
Now I need to add a functionality like QTableModel's setEditStrategy so I can cache all changes and accept or revert them using buttons. PyQt apparently doesn't allow multiple inheritance and I cannot find sufficient documentation to re-implement this method in my custom model, therefor here's the question:

How can I re-implement QSqlTableModel.setEditStragety (or something like it) including RevertAll() and SubmitAll() in an editable QSqlQueryModel?

Here's a CVME: (I have out-commented the parts of of my Example class I would like to get working)

import sys

from PyQt5.QtCore import Qt
from PyQt5.QtSql import QSqlDatabase, QSqlQuery, QSqlQueryModel, QSqlTableModel
from PyQt5.QtWidgets import QApplication, QTableView, QWidget, QGridLayout
from PyQt5.Qt import QPushButton

db_file = "test.db"


def create_connection(file_path):
 db = QSqlDatabase.addDatabase("QSQLITE")
 db.setDatabaseName(file_path)
 if not db.open():
 print("Cannot establish a database connection to !".format(file_path))
 return False
 return True


def fill_tables():
 q = QSqlQuery()
 q.exec_("DROP TABLE IF EXISTS Manufacturers;")
 q.exec_("CREATE TABLE Manufacturers (Company TEXT, Country TEXT);")
 q.exec_("INSERT INTO Manufacturers VALUES ('VW', 'Germany');")
 q.exec_("INSERT INTO Manufacturers VALUES ('Honda' , 'Japan');")

 q.exec_("DROP TABLE IF EXISTS Cars;")
 q.exec_("CREATE TABLE Cars (Company TEXT, Model TEXT, Year INT);")
 q.exec_("INSERT INTO Cars VALUES ('Honda', 'Civic', 2009);")
 q.exec_("INSERT INTO Cars VALUES ('VW', 'Golf', 2013);")
 q.exec_("INSERT INTO Cars VALUES ('VW', 'Polo', 1999);")


class SqlQueryModel_editable(QSqlQueryModel):
 """a subclass of QSqlQueryModel where individual columns can be defined as editable
 """
 def __init__(self, editables):
 """editables should be a dict of format: 
 INT editable_column_nr : (STR update query to be performed when changes are made on this column
 INT model's column number for the filter-column (used in the where-clause),
 ) 
 """
 super().__init__()
 self.editables = editables

 def flags(self, index):
 fl = QSqlQueryModel.flags(self, index)
 if index.column() in self.editables:
 fl |= Qt.ItemIsEditable
 return fl

 def setData(self, index, value, role=Qt.EditRole):
 if role == Qt.EditRole:
 mycolumn = index.column()
 if mycolumn in self.editables:
 (query, filter_col) = self.editables[mycolumn]
 filter_value = self.index(index.row(), filter_col).data()
 q = QSqlQuery(query.format(value, filter_value))
 result = q.exec_()
 if result:
 self.query().exec_()
 else:
 print(self.query().lastError().text())
 return result
 return QSqlQueryModel.setData(self, index, value, role)

 def setFilter(self, myfilter):
 text = (self.query().lastQuery() + " WHERE " + myfilter)
 self.setQuery(text)


class Example(QWidget):
 def __init__(self):
 super().__init__()
 self.resize(400, 150)

 self.createModel()
 self.initUI()

 def createModel(self):
 editables = 1 : ("UPDATE Manufacturers SET Country = '' WHERE Company = ''", 2)
 self.model = SqlQueryModel_editable(editables)
 query = '''
 SELECT (comp.company || " " || cars.model) as Car,
 comp.Country,
 cars.company,
 (CASE WHEN cars.Year > 2000 THEN 'yes' ELSE 'no' END) as this_century
 from manufacturers comp left join cars
 on comp.company = cars.company
 '''
 q = QSqlQuery(query)
 self.model.setQuery(q)
 self.model.setFilter("cars.Company = 'VW'")
# self.model.setEditStrategy(QSqlTableModel.OnManualSubmit)

 def initUI(self):
 self.layout = QGridLayout()
 self.setLayout(self.layout)
 self.view = QTableView()
 self.view.setModel(self.model)
 self.view.hideColumn(2)
 self.layout.addWidget(self.view,0,0,1,2)

 self.accept_btn = QPushButton("Accept Changes")
# self.accept_btn.clicked.connect(self.model.submitAll)
 self.layout.addWidget(self.accept_btn, 1,0)
 self.reject_btn = QPushButton("Reject Changes")
# self.reject_btn.clicked.connect(self.model.revertAll)
 self.layout.addWidget(self.reject_btn, 1,1)


if __name__ == '__main__':
 app = QApplication(sys.argv)
 if not create_connection(db_file):
 sys.exit(-1)

 fill_tables()

 ex = Example()
 ex.show()
 sys.exit(app.exec_())

Edit to clarify:

I need an editable QSqlQueryModel, on which I can use submitAll() and revertAll(), so that changes to the model's data are only accepted after an Accept-button is clicked, or can be reverted using a "Reject" button.