如何在 python 和 qml 中自动插入/编辑 QAbstractListModel 更新?
问题描述
我正在尝试插入/编辑从 pyqt5 中的 QAbstractListModel 子类化的 python 列表.这个 python 列表是在 qml 中 ListView 元素的 model 属性中读取的.我在 qml 中显示数据没有问题.当我尝试将新数据附加到 python 列表中时出现问题.
i am trying to insert/edit a python list that is subclassed from QAbstractListModel in pyqt5. this python list is read in the model property of ListView element in qml. i have no issues displaying the data in qml. problem arises when i try to append new data into the python list.
以下是我目前所做的:
main.py:
import sys, model2
from PyQt5.QtCore import QUrl
from PyQt5.QtWidgets import QApplication
from PyQt5.QtQuick import QQuickView
class MainWindow(QQuickView):
def __init__(self, parent=None):
super().__init__(parent)
self.model = model2.PersonModel()
self.rootContext().setContextProperty('PersonModel', self.model)
self.rootContext().setContextProperty('MainWindow', self)
self.setSource(QUrl('test2.qml'))
myApp = QApplication(sys.argv)
ui = MainWindow()
ui.show()
sys.exit(myApp.exec_())
model2.py
from PyQt5.QtCore import QAbstractListModel, Qt, pyqtSignal, pyqtSlot
class PersonModel(QAbstractListModel):
Name = Qt.UserRole + 1
Age = Qt.UserRole + 2
personChanged = pyqtSignal()
def __init__(self, parent=None):
super().__init__(parent)
self.persons = [
{'name': 'jon', 'age': 20},
{'name': 'jane', 'age': 25}
]
def data(self, QModelIndex, role):
row = QModelIndex.row()
if role == self.Name:
return self.persons[row]["name"]
if role == self.Age:
return self.persons[row]["age"]
def rowCount(self, parent=None):
return len(self.persons)
def roleNames(self):
return {
Qt.UserRole + 1: b'name',
Qt.UserRole + 2: b'age'
}
@pyqtSlot()
def addData(self):
self.beginResetModel()
self.persons = self.persons.append({'name': 'peter', 'age': 22})
self.endResetModel()
print(self.persons)
@pyqtSlot()
def editData(self):
print(self.model.persons)
test2.qml:
import QtQuick 2.6
import QtQuick.Controls 2.2
Rectangle {
anchors.fill: parent
color: "lightgrey"
ListView {
id: listExample
anchors.fill: parent
model: PersonModel
delegate: Text {
text: name + " " + age
}
}
Button {
width: 50
height: 25
anchors.bottom: parent.bottom
text: "add"
onClicked: {
console.log("qml adding")
PersonModel.addData()
}
}
.
.
.
}
当我单击调用 model2.py 中的 addData 方法的添加按钮时发生错误.错误在于 rowCount 并且错误消息说 TypeError: object of type 'NoneType' has no len().我是否必须发出更改或传递一些索引和角色值，以便 qml 知道什么是新/旧并仅相应地反映更改?
error occurs when i click the add button which calls the addData method in model2.py. error lies in the rowCount and error message says TypeError: object of type 'NoneType' has no len(). do i have to emit the changes or pass in some index and role value so qml knows what is new/old and only reflect the changes accordingly?
非常感谢任何形式的指导！
any form of guidance is greatly appreciated!
解决方案
你得到的错误是由下面这行代码引起的:
The error you get is caused by the following line of code:
self.persons = self.persons.append({'name': 'peter', 'age': 22})
这是因为 append 函数没有返回任何东西，所以它是为了将 None 分配给 self.persons
It is caused because the append function does not return anything, so it was meant to assign None to self.persons
要插入新数据，您必须调用 beginInsertRows() 和 endInsertRows() 来通知视图更改.
To insert new data you must call beginInsertRows() and endInsertRows() to notify the view of the change.
数据方法必须与文档中显示的相同，即必须具有以下格式:
the data method must be identical to that shown in the documentation, ie it must have the following format:
def data(self, index, role=Qt.DisplayRole):
与rowCount方法相同:
The same with the rowCount method:
def rowCount(self, parent=QModelIndex()):
我已经实现了 addPerson、editPerson 和 deletePerson 方法，它们分别添加、编辑和删除列表中的数据.我还在 .qml 中添加了必要的项目以便能够对其进行测试.
I have implemented the methods addPerson, editPerson and deletePerson that adds, edits and deletes a data from the list respectively. Also I added the necessary items to the .qml to be able to test it.
model2.py
from PyQt5.QtCore import QAbstractListModel, Qt, pyqtSignal, pyqtSlot, QModelIndex
class PersonModel(QAbstractListModel):
NameRole = Qt.UserRole + 1
AgeRole = Qt.UserRole + 2
personChanged = pyqtSignal()
def __init__(self, parent=None):
super().__init__(parent)
self.persons = [
{'name': 'jon', 'age': 20},
{'name': 'jane', 'age': 25}
]
def data(self, index, role=Qt.DisplayRole):
row = index.row()
if role == PersonModel.NameRole:
return self.persons[row]["name"]
if role == PersonModel.AgeRole:
return self.persons[row]["age"]
def rowCount(self, parent=QModelIndex()):
return len(self.persons)
def roleNames(self):
return {
PersonModel.NameRole: b'name',
PersonModel.AgeRole: b'age'
}
@pyqtSlot(str, int)
def addPerson(self, name, age):
self.beginInsertRows(QModelIndex(), self.rowCount(), self.rowCount())
self.persons.append({'name': name, 'age': age})
self.endInsertRows()
@pyqtSlot(int, str, int)
def editPerson(self, row, name, age):
ix = self.index(row, 0)
self.persons[row] = {'name': name, 'age': age}
self.dataChanged.emit(ix, ix, self.roleNames())
@pyqtSlot(int)
def deletePerson(self, row):
self.beginRemoveColumns(QModelIndex(), row, row)
del self.persons[row]
self.endRemoveRows()
test2.qml
import QtQuick 2.6
import QtQuick.Controls 2.2
Rectangle {
anchors.fill: parent
color: "lightgrey"
ListView {
id: listExample
anchors.fill: parent
model: PersonModel
delegate:
Item {
width: 200
height: 60
Row {
Text {
width: 60
text: name + " " + age
horizontalAlignment: Text.AlignHCenter
anchors.verticalCenter: parent.verticalCenter
}
Button{
width: 20
text: "+"
onClicked: PersonModel.editPerson(index, name, age+1)
}
Button{
width: 20
text: "-"
onClicked: PersonModel.editPerson(index, name, age-1)
}
Button{
width: 20
text: "X"
onClicked: PersonModel.deletePerson(index)
}
}
}
}
Button {
width: 50
height: 25
anchors.bottom: parent.bottom
anchors.right: parent.right
text: "add"
onClicked: {
console.log("qml adding")
PersonModel.addPerson("luis", 22)
}
}
}
.py
@pyqtSlot(int, str, int)
def insertPerson(self, row, name, age):
self.beginInsertRows(QModelIndex(), row, row)
self.persons.insert(row, {'name': name, 'age': age})
self.endInsertRows()
.qml
PersonModel.insertPerson(2, "luis", 1111)
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