PySide2 SQLITE TableView

Question

在试图在QML QSQLITE TableView中显示来自TableView表的数据时，我无意中发现了这个答案，并试图对其进行跟踪。我理解重新实现data()和roleNames()的必要性，但是当涉及到PySide2中不存在的QVariant时，我遇到了问题。我得到了NameError: name 'QVariant' is not defined。我测试过从数据库中读取数据，它的工作原理。是否有任何数据类型可以代替QVariant在PySide2中使用？我的计划是让来自不同tables.This示例的多个数据源使用setContextProperty，在这种情况下使用qmlRegisterType更好吗？

SQLITE数据库

文件夹结构

├── ViewModel
│   └── QCond.py
├── Qml
│   └── Modellist.qml
└── qmlengine.py

qmlengine.py

import os
import sys
from PySide2.QtCore import QUrl, QStringListModel, QCoreApplication, Qt
from PySide2.QtGui import QGuiApplication
from PySide2.QtQml import QQmlApplicationEngine, qmlRegisterType
from PySide2.QtSql import QSqlDatabase, QSqlQuery, QSqlQueryModel
from ViewModel.QCond import *
if __name__ == "__main__":
    app = QGuiApplication(sys.argv)
    engine = QQmlApplicationEngine()
    db = QSqlDatabase.addDatabase("QSQLITE")
    db.setDatabaseName("C:\\Users\\terao\\Documents\\ctmd\\CatData.db")
    db.open()
    qry = QSqlQuery()
    qry=db.exec_("SELECT tip,s FROM uzad")
    tabmodel = QtCond()
    tabmodel.setQuery(qry)
    engine.rootContext().setContextProperty("tabmodel", tabmodel)
    engine.load(QUrl.fromLocalFile('Qml/Modellist.qml'))
    if not engine.rootObjects():
        sys.exit(-2)
    sys.exit(app.exec_())

QCond.py

import sys
from PySide2 import QtCore, QtGui, QtQml
from PySide2.QtCore import QObject, Qt,Signal, Slot, QUrl, QStringListModel, QCoreApplication
import sqlite3
from PySide2.QtSql import QSqlDatabase, QSqlQuery, QSqlQueryModel
class QtCond(QSqlQueryModel):
    def __init__(self):
        super(QtCond, self).__init__()

    def roleNames(self):
        roles = {
            Qt.UserRole + 1 : 'tip',
            Qt.UserRole + 2 : 's'
        }
        return roles

    def data(self, index, role):
        if role < Qt.UserRole:
            # caller requests non-UserRole data, just pass to papa
            return super(QtTabModel, self).data(index, role)

        # caller requests UserRole data, convert role to column (role - Qt.UserRole -1) to return correct data
        return super(QtTabModel, self).data(self.index(index.row(), role - Qt.UserRole -1), Qt.DisplayRole)

    @QtCore.Slot(result=QVariant)  # don't know how to return a python array/list, so just use QVariant
    def roleNameArray(self):
        # This method is used to return a list that QML understands
        list = []
        # list = self.roleNames().items()
        for key, value in self.roleNames().items():
            list.append(str(value))

        return QVariant(list)

Modellist.qml

import QtQuick 2.5
import QtQuick.Controls 1.4
import QtQuick.Controls 2.5

TableView {
    width: 1000
    height: 1000
    model: tabmodel
    TableViewColumn {
        role: "tip" // case-sensitive, must match a role returned by roleNames()
    }
    TableViewColumn {
        role: "s"
    }

}

任何帮助都是非常感谢的。提前谢谢。

Answer 1

在您的示例中，roleNameArray返回一个列表，正如我在这个答案中指出的那样，您必须使用"QVariantList“。另一方面，我根据我以前的答案：(1)，(2)对示例进行了改进，考虑到解决方案是：

├── db
│   └── CatData.db
├── qml
│   └── Modellist.qml
├── qmlengine.py
└── ViewModel
    └── model.py

ViewModel/model.py

from PySide2 import QtCore, QtSql


class SqlQueryModel(QtSql.QSqlQueryModel):
    def data(self, index, role=QtCore.Qt.DisplayRole):
        value = None
        if index.isValid():
            if role < QtCore.Qt.UserRole:
                value = super(SqlQueryModel, self).data(index, role)
            else:
                columnIdx = role - QtCore.Qt.UserRole - 1
                modelIndex = self.index(index.row(), columnIdx)
                value = super(SqlQueryModel, self).data(
                    modelIndex, QtCore.Qt.DisplayRole
                )
        return value

    def roleNames(self):
        roles = dict()
        for i in range(self.record().count()):
            roles[QtCore.Qt.UserRole + i + 1] = self.record().fieldName(i).encode()
        return roles

    @QtCore.Slot(result="QVariantList")
    def roleNameArray(self):
        names = []
        for i in range(self.record().count()):
            names.append(self.record().fieldName(i))
        return names

qml/Modellist.qml

import QtQuick 2.5
import QtQuick.Controls 1.4
import QtQuick.Controls 2.5

ApplicationWindow{
    width: 1000
    height: 1000
    visible: true

    TableView {
        anchors.fill: parent
        model: tabmodel

        /*TableViewColumn {
            role: "tip"
        }
        TableViewColumn {
            role: "s"
        }*/

        Component.onCompleted: {
            var roles = model.roleNameArray()
            for (var i=0; i<roles.length; i++) {
              var column = addColumn( Qt.createQmlObject(
                "import QtQuick.Controls 1.1; TableViewColumn {}",
                this) )
              column.role = roles[i]
              column.title = roles[i]
            }
        }
    }
}

qmlengine.py

import os
import sys

from PySide2 import QtCore, QtGui, QtSql, QtQml

from ViewModel.model import SqlQueryModel

def create_connection(path):
    db = QtSql.QSqlDatabase.addDatabase('QSQLITE')
    db.setDatabaseName(path)
    if not db.open():
        print('''Unable to establish a database connection.\n
            This example needs SQLite support. Please read
            the Qt SQL driver documentation for information
            how to build it.\n\n Click Cancel to exit.''')
        return False
    return True

if __name__ == "__main__":
    current_dir = os.path.dirname(os.path.realpath(__file__))
    app = QtGui.QGuiApplication(sys.argv)
    engine = QtQml.QQmlApplicationEngine()
    db_path = os.path.join(current_dir, "db", "CatData.db")
    if not create_connection(db_path):
        sys.exit(-1)

    tabmodel = SqlQueryModel()
    tabmodel.setQuery("SELECT tip,s FROM uzad")
    engine.rootContext().setContextProperty("tabmodel", tabmodel)
    qml_path = os.path.join("qml", "Modellist.qml")
    engine.load(QtCore.QUrl.fromLocalFile(qml_path))
    if not engine.rootObjects():
        sys.exit(-2)
    sys.exit(app.exec_()) 

输出：

​

​

qmlRegisterType的目标是通过抽象源和实现在QML中注册Python/C++类型。在您的情况下，如果您想注册它，最好是查询qproperty，以便可以从QML访问它：

ViewModel/model.py

from PySide2 import QtCore, QtSql


class SqlQueryModel(QtSql.QSqlQueryModel):

    queryStrChanged = QtCore.Signal(str)

    def get_query_str(self):
        return self.query().lastQuery()

    def set_query_str(self, query):
        if self.get_query_str() == query:
            return
        self.setQuery(query)
        self.queryStrChanged.emit(query)

    query_str = QtCore.Property(
        str, fget=get_query_str, fset=set_query_str, notify=queryStrChanged
    )

    def data(self, index, role=QtCore.Qt.DisplayRole):
        value = None
        if index.isValid():
            if role < QtCore.Qt.UserRole:
                value = super(SqlQueryModel, self).data(index, role)
            else:
                columnIdx = role - QtCore.Qt.UserRole - 1
                modelIndex = self.index(index.row(), columnIdx)
                value = super(SqlQueryModel, self).data(
                    modelIndex, QtCore.Qt.DisplayRole
                )
        return value

    def roleNames(self):
        roles = dict()
        for i in range(self.record().count()):
            roles[QtCore.Qt.UserRole + i + 1] = self.record().fieldName(i).encode()
        return roles

    @QtCore.Slot(result="QVariantList")
    def roleNameArray(self):
        names = []
        for i in range(self.record().count()):
            names.append(self.record().fieldName(i))
        return names

qml/Modellist.qml

import QtQuick 2.5
import QtQuick.Controls 1.4
import QtQuick.Controls 2.5

import mycomponents 1.0

ApplicationWindow{
    width: 1000
    height: 1000
    visible: true

    SqlQueryModel{
        id: tabmodel
        query_str: "SELECT tip,s FROM uzad"
    }

    TableView {
        anchors.fill: parent
        model: tabmodel

        /*TableViewColumn {
            role: "tip"
        }
        TableViewColumn {
            role: "s"
        }*/

        Component.onCompleted: {
            var roles = model.roleNameArray()
            for (var i=0; i<roles.length; i++) {
              var column = addColumn( Qt.createQmlObject(
                "import QtQuick.Controls 1.1; TableViewColumn {}",
                this) )
              column.role = roles[i]
              column.title = roles[i]
            }
        }
    }
}

qmlengine.py

import os
import sys

from PySide2 import QtCore, QtGui, QtSql, QtQml

from ViewModel.model import SqlQueryModel

def create_connection(path):
    db = QtSql.QSqlDatabase.addDatabase('QSQLITE')
    db.setDatabaseName(path)
    if not db.open():
        print('''Unable to establish a database connection.\n
            This example needs SQLite support. Please read
            the Qt SQL driver documentation for information
            how to build it.\n\n Click Cancel to exit.''')
        return False
    return True

if __name__ == "__main__":
    current_dir = os.path.dirname(os.path.realpath(__file__))
    QtQml.qmlRegisterType(SqlQueryModel, "mycomponents", 1, 0, "SqlQueryModel")
    app = QtGui.QGuiApplication(sys.argv)
    engine = QtQml.QQmlApplicationEngine()
    db_path = os.path.join(current_dir, "db", "CatData.db")
    if not create_connection(db_path):
        sys.exit(-1)
    qml_path = os.path.join("qml", "Modellist.qml")
    engine.load(QtCore.QUrl.fromLocalFile(qml_path))
    if not engine.rootObjects():
        sys.exit(-2)
    sys.exit(app.exec_())