如何在python和qml自动更新中插入/编辑QAbstractListModel？

Question

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我正在尝试插入/编辑一个从QAbstractListModelpyqt5子类化的 python 列表。这个python列表是在qmlmodel中ListView元素的属性中读取的。我在 qml 中显示数据没有问题。当我尝试将新数据附加到 python 列表时出现问题。

以下是我到目前为止所做的：

主要.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_())

模型2.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)

测试2.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addDatamodel2.py 中的方法的添加按钮时发生错误。错误在于rowCount和错误消息说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 知道什么是新的/旧的，并且只相应地反映更改？

非常感谢任何形式的指导！

Answer 1

您得到的错误是由以下代码行引起的：

self.persons = self.persons.append({'name': 'peter', 'age': 22})

这是因为 append 函数没有返回任何东西，所以它的意思是将 None 分配给 self.persons

要插入新数据，您必须调用beginInsertRows()并endInsertRows()通知视图更改。

数据方法必须与文档中显示的相同，即它必须具有以下格式：

def data(self, index, role=Qt.DisplayRole):

与 rowCount 方法相同：

def rowCount(self, parent=QModelIndex()):

我已经实现了分别从列表中添加、编辑和删除数据的 addPerson、editPerson 和 deletePerson 方法。我还向 .qml 添加了必要的项目以便能够对其进行测试。

模型2.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()

测试2.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)
        }
    }
}

编辑：

.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)