问题描述
我开始学习 Qt4 模型/视图编程,我有初学者问题.
I'm started to learning Qt4 Model/View Programming and I have beginner question.
我有一个简单的应用程序,它在 QTableView
中显示 sqlite 表:
I have simple application which show sqlite table in QTableView
:
class Model(QtSql.QSqlTableModel):
def __init__(self, parent=None):
super(Model, self).__init__(parent)
self.setEditStrategy(QtSql.QSqlTableModel.OnFieldChange)
self.setTable("test")
self.select()
class App(QtGui.QMainWindow):
def __init__(self, model):
QtGui.QMainWindow.__init__(self)
self.ui = Ui_MainWindow()
self.ui.setupUi(self)
self.ui.tableView.setModel(model)
if __name__ == "__main__":
myDb = QtSql.QSqlDatabase.addDatabase("QSQLITE")
myDb.setDatabaseName("test.db")
if not myDb.open():
print 'FIXME'
model = Model()
app = QtGui.QApplication(sys.argv)
window = App(model)
window.show()
sys.exit(app.exec_())
这里是数据库的样子:
sqlite> create table test (a INTEGER, b INTEGER, c STRING);
sqlite> insert into test VALUES(1, 2, "xxx");
sqlite> insert into test VALUES(6, 7, "yyy");
所以我得到了类似的信息:
So I'm getting something like:
+---+---+-----+
| a | b | c |
+---+---+-----+
| 1 | 2 | xxx |
+---+---+-----+
| 6 | 7 | yyy |
+---+---+-----+
是否可以修改 Model
以在 QTableView
中包含类似虚拟列的内容?例如类似:
Is it possible to modify Model
to have in QTableView
something like virtual column? For example something like:
+---+---+-----+-----+
| a | b | sum | c |
+---+---+-----+-----+
| 1 | 2 | 3 | xxx |
+---+---+-----+-----+
| 6 | 7 | 13 | yyy |
+---+---+-----+-----+
或者我应该用其他方式来做吗?
Or maybe I should do it in some other way?
推荐答案
是的,您可以这样做.尽管 @BrtH 的答案 是相关的,但模型很棘手,而且很容易迷路.所以我认为更多的例子会更好.
Yes, you can do that. Although @BrtH's answer is relevant, models are tricky and it's easy to get lost. So I thought a more case in point example would be better.
就我个人而言,我会使用从 QAbstractProxyModel
派生的代理模型.但是,在您的情况下,重新实现 QSqlTableModel
也是可行的.以下是您目标的实现.请注意,了解模型/视图方法 以便您了解每种方法的作用.
Personally, I'd use a proxy model derived from QAbstractProxyModel
. But, in your case reimplementing QSqlTableModel
is also feasible. Below is an implementation for your goal. Note that, it's essential for you to know basics of Model/View methodology so that you understand what each method does.
class Model(QtSql.QSqlTableModel):
def __init__(self, parent=None):
super(Model, self).__init__(parent)
self.setEditStrategy(QtSql.QSqlTableModel.OnFieldChange)
self.setTable("test")
self.select()
def columnCount(self, parent=QtCore.QModelIndex()):
# this is probably obvious
# since we are adding a virtual column, we need one more column
return super(Model, self).columnCount()+1
def data(self, index, role=QtCore.Qt.DisplayRole):
if role == QtCore.Qt.DisplayRole and index.column()==2:
# 2nd column is our virtual column.
# if we are there, we need to calculate and return the value
# we take the first two columns, get the data, turn it to integer and sum them
# [0] at the end is necessary because pyqt returns value and a bool
# http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qvariant.html#toInt
return sum(self.data(self.index(index.row(), i)).toInt()[0] for i in range(2))
if index.column() > 2:
# if we are past 2nd column, we need to shift it to left by one
# to get the real value
index = self.index(index.row(), index.column()-1)
# get the value from base implementation
return super(Model, self).data(index, role)
def headerData(self, section, orientation, role=QtCore.Qt.DisplayRole):
# this is similar to `data`
if section==2 and orientation==QtCore.Qt.Horizontal and role==QtCore.Qt.DisplayRole:
return 'Sum'
if section > 2 and orientation==QtCore.Qt.Horizontal:
section -= 1
return super(Model, self).headerData(section, orientation, role)
def flags(self, index):
# since 2nd column is virtual, it doesn't make sense for it to be Editable
# other columns can be Editable (default for QSqlTableModel)
if index.column()==2:
return QtCore.Qt.ItemIsSelectable | QtCore.Qt.ItemIsEnabled
return QtCore.Qt.ItemIsSelectable | QtCore.Qt.ItemIsEnabled | QtCore.Qt.ItemIsEditable
def setData(self, index, data, role):
# similar to data.
# we need to be careful when setting data (after edit)
# if column is after 2, it is actually the column before that
if index.column() > 2:
index = self.index(index.row(), index.column()-1)
return super(Model, self).setData(index, data, role)
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