python - 如何使用 model() 删除项目后清理困惑

Question

下面的代码创建一个带有模型的 QListView。单击其项目会将其从模型中删除。但 QListView 仍然报告模型的项目数量保持不变(就像没有删除项目一样)。有什么办法可以解决吗？

class Model(QtCore.QAbstractListModel):
    def __init__(self):
        QtCore.QAbstractListModel.__init__(self)
        self.items=[] 
        self.modelDict={}       

    def rowCount(self, parent=QtCore.QModelIndex()):
        return len(self.modelDict)   

    def data(self, index, role):
        if not index.isValid():
            return QtCore.QVariant()
        if not (0 <= index.row() < len(self.items)):
            return QtCore.QVariant()

        if not index.isValid():
            return QtCore.QVariant()
        if role==QtCore.Qt.ItemDataRole:
            key=str(index.data().toString())
            returnedValue=self.modelDict.get(key)
            return QtCore.QVariant(returnedValue) 

        elif role==QtCore.Qt.DisplayRole:
            row=index.row()
            itemTitle=self.items[row]
            return QtCore.QVariant(itemTitle) 

    def addItems(self):
        for key in self.modelDict:
            index=QtCore.QModelIndex()
            self.beginInsertRows(index, 0, 0)
            self.items.append(key)

            inst=self.modelDict.get(key)
            self.setData(index, QtCore.QVariant(inst), QtCore.Qt.DisplayRole)            

        self.endInsertRows()        

    def removeByIndex(self, index):
        if not index.isValid(): return
        row=index.row()
        self.beginRemoveRows(QtCore.QModelIndex(), row, 0)
        self.items=self.items[:row]+self.items[row+1:]
        self.endRemoveRows()

class ListView(QtGui.QListView):
    def __init__(self):
        super(ListView, self).__init__()
        self.model= Model()
        self.model.modelDict=elements
        self.model.addItems()
        self.setModel(self.model)
        self.clicked.connect(self.itemClicked)
        self.show()

    def itemClicked(self, index):   
        print 'NUMBER OF ITEMS BEFORE DELETE: %s'%self.model.rowCount()   
        self.model.removeByIndex(index)
        print 'NUMBER OF ITEMS AFTER DELETE: %s'%self.model.rowCount()          

window=ListView()
sys.exit(app.exec_())

Answer 1

有关如何从模型中删除项目的完整示例。

import os,sys
from PyQt4 import QtCore, QtGui
app=QtGui.QApplication(sys.argv)
elements={'Animals':{1:'Bison',2:'Panther',3:'Elephant'},'Birds':{1:'Duck',2:'Hawk',3:'Pigeon'},'Fish':{1:'Shark',2:'Salmon',3:'Piranha'}}

class Model(QtCore.QAbstractListModel):
    def __init__(self):
        QtCore.QAbstractListModel.__init__(self)
        self.items=[] 
        self.modelDict={}       

    def rowCount(self, parent=QtCore.QModelIndex()):
        return len(self.items)   

    def data(self, index, role):
        if not index.isValid():
            return QtCore.QVariant()
        if not (0 <= index.row() < len(self.items)):
            return QtCore.QVariant()

        if not index.isValid():
            return QtCore.QVariant()
        if role==QtCore.Qt.ItemDataRole:
            key=str(index.data().toString())
            returnedValue=self.modelDict.get(key)
            return QtCore.QVariant(returnedValue) 

        elif role==QtCore.Qt.DisplayRole:
            row=index.row()
            itemTitle=self.items[row]
            return QtCore.QVariant(itemTitle) 

    def addItems(self):
        for key in self.modelDict:
            index=QtCore.QModelIndex()
            self.beginInsertRows(index, 0, 0)
            self.items.append(key)

            inst=self.modelDict.get(key)
            self.setData(index, QtCore.QVariant(inst), QtCore.Qt.DisplayRole)            

        self.endInsertRows()        

    def removeByIndex(self, index):
        if not index.isValid(): return
        row=index.row()
        self.beginRemoveRows(QtCore.QModelIndex(), row, 0)
        self.items=self.items[:row]+self.items[row+1:]
        key=str(index.data().toString())
        if self.modelDict.get(key): self.modelDict.pop(key,None)
        self.endRemoveRows()

class ListView(QtGui.QListView):
    def __init__(self):
        super(ListView, self).__init__()
        self.model= Model()
        self.model.modelDict=elements
        self.model.addItems()
        self.setModel(self.model)
        self.clicked.connect(self.itemClicked)
        self.show()

    def itemClicked(self, index):   
        print 'NUMBER OF ITEMS BEFORE DELETE: %s'%self.model.rowCount()   
        self.model.removeByIndex(index)
        print 'NUMBER OF ITEMS AFTER DELETE: %s'%self.model.rowCount()          

window=ListView()
sys.exit(app.exec_())