Understanding the Problem and Solution
The problem at hand revolves around updating a QTableView when its data source changes. A QAbstractTableModel serves as the “base” table model, while a QSortFilterProxyModel is used to filter and sort the data. However, the current implementation does not update the QTableView after the data source changes.
Background Information
To tackle this issue, it’s essential to understand how the QAbstractTableModel and QSortFilterProxyModel interact with each other. The QAbstractTableModel is responsible for providing data to the view, while the QSortFilterProxyModel acts as an intermediary between the model and the view, filtering and sorting the data before it reaches the view.
Update Strategy
To update the QTableView when its data source changes, we need to follow these steps:
- Update the
DataStoreobject with new data. - Notify the
ProxyModelof the change by callingself.proxy_model.setSourceModel(self.model)and thenself.proxy_model.update(). - Finally, update the
QTableViewby setting its model to the updatedProxyModel.
Code Explanation
Here’s a detailed explanation of the changes made:
DataStore Class Updates
The DataStore class now holds a reference to the new data source.
class DataStore(object):
def __init__(self):
# ...
self.model = TableModel(self.df)
self.proxy_model = ProxyModel()
self.proxy_model.setSourceModel(self.model)
self.proxy_model.setDynamicSortFilter(True)
@property
def df(self):
return self.model.df
@df.setter
def df(self, df):
# Update the data source here
self.model.beginResetModel()
self.model.__data = df.copy()
self.model.endResetModel()
The df property now updates the model’s internal state when its value changes.
Proxy Model Class Updates
No changes are required in the ProxyModel class, as it already acts as a filter and does not affect the data source directly.
class ProxyModel(QtCore.QSortFilterProxyModel):
# ...
def filterAcceptsRow(self, sourceRow, sourceParent):
# ... (unchanged)
Table Model Class Updates
The TableModel class now updates its internal state when the data source changes.
class TableModel(QtCore.QAbstractTableModel):
def __init__(self, data):
super().__init__()
self.__data = data
@property
def df(self):
return self.__data
@df.setter
def df(self, df):
# Update the data source here
self.beginResetModel()
self.__data = df.copy()
self.endResetModel()
# ... (unchanged)
The TableModel class now updates its internal state when the data source changes.
MainWindow Class Updates
Finally, the MainWindow class has been updated to reflect these changes.
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.ds = DataStore()
# ...
def on_event(self):
# ...
data = {
"Name": ["new_name1", "new_name2", "new_name3"],
"Value": ["new_value1", "new_value2", "new_value3"],
"Description": ["new_descr1", "new_descr2", "new_descr3"],
"Setting": ["TRUE", "FALSE", "TRUE"],
}
new_df = pd.DataFrame(data, columns=["Name", "Value", "Setting"])
self.ds.df = new_df
The MainWindow class now updates the data source after a change occurs.
Conclusion
In this article, we explored how to update a QTableView when its data source changes using a QAbstractTableModel and a QSortFilterProxyModel. We modified the classes to include an update strategy that notifies both models of any changes to their data sources. This ensures seamless updates between the view, model, and proxy model, providing a robust solution for dynamic data rendering in Qt-based applications.
Code
Here’s the complete code with all the modifications:
import sys
import pandas as pd
from PySide2 import QtCore, QtGui, QtWidgets
from PySide2.QtCore import Qt
class DataStore(object):
def __init__(self):
# ...
self.model = TableModel(self.df)
self.proxy_model = ProxyModel()
self.proxy_model.setSourceModel(self.model)
self.proxy_model.setDynamicSortFilter(True)
@property
def df(self):
return self.model.df
@df.setter
def df(self, df):
# Update the data source here
self.model.beginResetModel()
self.model.__data = df.copy()
self.model.endResetModel()
class ProxyModel(QtCore.QSortFilterProxyModel):
def filterAcceptsRow(self, sourceRow, sourceParent):
print("Entered filterAcceptsRow function with source row: {}".format(sourceRow))
idx = self.sourceModel().index(sourceRow, 2, sourceParent)
value = idx.data()
if value == "TRUE":
return True
if value == "FALSE":
return False
class TableModel(QtCore.QAbstractTableModel):
def __init__(self, data):
super().__init__()
self.__data = data
@property
def df(self):
return self.__data
@df.setter
def df(self, df):
# Update the data source here
self.beginResetModel()
self.__data = df.copy()
self.endResetModel()
def data(self, index, role):
if role == Qt.DisplayRole:
value = self.__data.iloc[index.row(), index.column()]
return str(value)
def rowCount(self, index):
return self.__data.shape[0]
def columnCount(self, index):
return self.__data.shape[1]
def headerData(self, section, orientation, role):
if role == Qt.DisplayRole:
if orientation == Qt.Horizontal:
return str(self.__data.columns[section])
if orientation == Qt.Vertical:
return str(self.__data.index[section])
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
self.ds = DataStore()
# ...
def on_event(self):
data = {
"Name": ["new_name1", "new_name2", "new_name3"],
"Value": ["new_value1", "new_value2", "new_value3"],
"Description": ["new_descr1", "new_descr2", "new_descr3"],
"Setting": ["TRUE", "FALSE", "TRUE"],
}
new_df = pd.DataFrame(data, columns=["Name", "Value", "Setting"])
self.ds.df = new_df
Last modified on 2025-01-19