将QAbstractListModel与QML同步

Question

我有一个实现QAbstractListModel的简单StudentListModel类。

class StudentListModel(QAbstractListModel):
    NAME = Qt.UserRole + 1
    AGE = Qt.UserRole + 2

    def __init__(self, students):
        super().__init__()
        self.students = students

    def roleNames(self):
        return {
            StudentListModel.NAME: b'name',
            StudentListModel.AGE: b'age',
        }

    def rowCount(self, parent=None, *args, **kwargs):
        return len(self.students)

    def data(self, QModelIndex, role=None):
        row = self.students[QModelIndex.row()]

        if role == StudentListModel.NAME:
            return row["name"]
        elif role == StudentListModel.AGE:
            return row["age"]

        return None

    def remove(self, index):
        self.students.pop(index)

将StudentListModel传递给QML文件。QML将显示models条目。

import QtQuick 2.15
import QtQuick.Controls 2.15

Rectangle {
  id: container

  signal remove(int index)

  Column {
      spacing: 15

      Repeater {
          model: studentListModel

          Row {
              spacing: 10

              Text {
                  text: model.name
              }

              Button {
                  text: "Remove"
                  onClicked: container.remove(index)
              }
          }
      }
  }
}

连接QML和StudentListModel的代码如下所示：

def main():
    students = [
        {"name": "Vitaliy  ", "age": "21"},
        {"name": "Eugene", "age": "26"},
        {"name": "Tommy", "age": "26"}
    ]

    model = StudentListModel(students)

    app = QApplication(sys.argv)
    widget = QQuickWidget()

    widget.setSource(QUrl('stack.qml'))
    widget.rootContext().setContextProperty('studentListModel', model)
    widget.rootObject().remove.connect(lambda index: model.remove(index))

    widget.setGeometry(0, 0, 320, 800)
    widget.show()

    return app.exec_()


if __name__ == '__main__':
    sys.exit(main())

以下是该应用程序的运行截图：

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在QML中显示模型条目没有问题。问题是当我想要删除一个条目的时候。当我单击remove时，QML获取所单击条目的索引并发送一个信号。main()块将通过lambda函数处理信号发送。Lambda函数将接收索引，并通过传递接收到的索引从模型中调用remove方法。在此之后，模型将删除条目，但是QML不会显示更新后的模型。有没有办法将模型与QML同步，这样当一个条目被删除时，它也会在QML中被删除？

Answer 1

您必须在删除之前和之后分别调用beginRemoveRows和endRemoveRows方法：

class StudentListModel(QAbstractListModel):
    NAME = Qt.UserRole + 1
    AGE = Qt.UserRole + 2

    def __init__(self, students):
        super().__init__()
        self.students = students

    def roleNames(self):
        return {
            StudentListModel.NAME: b"name",
            StudentListModel.AGE: b"age",
        }

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

    def data(self, index, role=Qt.DisplayRole):
        row = self.students[index.row()]

        if role == StudentListModel.NAME:
            return row["name"]
        elif role == StudentListModel.AGE:
            return row["age"]

    def remove(self, index):
        self.beginRemoveRows(QModelIndex(), index, index)
        self.students.pop(index)
        self.endRemoveRows()