如何刷新组合框委托中代表QSqlRelationalTablemodel数据的项目列表

Question

我最近检查了Mark Summerfield的“使用Python和Qt进行快速GUI编程”第15章中的示例，该示例介绍了SQL数据库TableView建模的用法。在这个原始示例中，我发现了一些功能失调的功能，它阻止了表视图刷新组合框委托（即QSqlRelation）。简单地说，一旦修改了关系表，就不会更新表视图中表示QSqlRelationalTableModel数据的组合框委托。

原始文件名为chap15 / assetmanager.pyw，可以找到elsewhere。下面，我提供了重现该问题所必需的代码段。

在此示例中，为操作和类别（QSqlRelationalTableModel）建立了与QSqlTableModel（self.assetModel和self.logModel）的关系，可以使用组合框委托（LogDelegate或AssetDelegate）对其进行修改。可以通过ReferenceDataDlg对话框添加新的动作或类别。

在类别中添加的新记录

但是，一旦对话框ReferenceDataDlg关闭，即使新记录已存在于动作或类别的SQL表中，新创建的记录也不会出现在组合框委托中。

组合框委托未刷新

如何在表视图中以编程方式刷新组合框委托中的项目列表：self.assetView和self.logView？

from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
from future_builtins import *

import os
import sys
from PyQt4.QtCore import (PYQT_VERSION_STR, QDate, QFile, QRegExp,
        QString, QVariant, Qt, SIGNAL)
from PyQt4.QtGui import (QApplication, QCursor, QDateEdit, QDialog,
        QHBoxLayout, QLabel, QLineEdit, QMessageBox, QPixmap,
        QPushButton, QRegExpValidator, QStyleOptionViewItem, QTableView,
        QVBoxLayout)
from PyQt4.QtSql import (QSqlDatabase, QSqlQuery, QSqlRelation,
        QSqlRelationalDelegate, QSqlRelationalTableModel, QSqlTableModel)

MAC = True
try:
    from PyQt4.QtGui import qt_mac_set_native_menubar
except ImportError:
    MAC = False

ID = 0
NAME = ASSETID = 1
CATEGORYID = DATE = DESCRIPTION = 2
ROOM = ACTIONID = 3

ACQUIRED = 1

def createFakeData():
    import random

    print("Dropping tables...")
    query = QSqlQuery()
    query.exec_("DROP TABLE assets")
    query.exec_("DROP TABLE logs")
    query.exec_("DROP TABLE actions")
    query.exec_("DROP TABLE categories")
    QApplication.processEvents()

    print("Creating tables...")
    query.exec_("""CREATE TABLE actions (
                id INTEGER PRIMARY KEY AUTOINCREMENT UNIQUE NOT NULL,
                name VARCHAR(20) NOT NULL,
                description VARCHAR(40) NOT NULL)""")
    query.exec_("""CREATE TABLE categories (
                id INTEGER PRIMARY KEY AUTOINCREMENT UNIQUE NOT NULL,
                name VARCHAR(20) NOT NULL,
                description VARCHAR(40) NOT NULL)""")
    query.exec_("""CREATE TABLE assets (
                id INTEGER PRIMARY KEY AUTOINCREMENT UNIQUE NOT NULL,
                name VARCHAR(40) NOT NULL,
                categoryid INTEGER NOT NULL,
                room VARCHAR(4) NOT NULL,
                FOREIGN KEY (categoryid) REFERENCES categories)""")
    query.exec_("""CREATE TABLE logs (
                id INTEGER PRIMARY KEY AUTOINCREMENT UNIQUE NOT NULL,
                assetid INTEGER NOT NULL,
                date DATE NOT NULL,
                actionid INTEGER NOT NULL,
                FOREIGN KEY (assetid) REFERENCES assets,
                FOREIGN KEY (actionid) REFERENCES actions)""")
    QApplication.processEvents()

    print("Populating tables...")
    query.exec_("INSERT INTO actions (name, description) "
                "VALUES ('Acquired', 'When installed')")
    query.exec_("INSERT INTO actions (name, description) "
                "VALUES ('Broken', 'When failed and unusable')")
    query.exec_("INSERT INTO actions (name, description) "
                "VALUES ('Repaired', 'When back in service')")
    query.exec_("INSERT INTO actions (name, description) "
                "VALUES ('Routine maintenance', "
                "'When tested, refilled, etc.')")
    query.exec_("INSERT INTO categories (name, description) VALUES "
                "('Computer Equipment', "
                "'Monitors, System Units, Peripherals, etc.')")
    query.exec_("INSERT INTO categories (name, description) VALUES "
                "('Furniture', 'Chairs, Tables, Desks, etc.')")
    query.exec_("INSERT INTO categories (name, description) VALUES "
                "('Electrical Equipment', 'Non-computer electricals')")
    today = QDate.currentDate()
    floors = range(1, 12) + range(14, 28)
    monitors = (('17" LCD Monitor', 1),
                ('20" LCD Monitor', 1),
                ('21" LCD Monitor', 1),
                ('21" CRT Monitor', 1),
                ('24" CRT Monitor', 1))
    computers = (("Computer (32-bit/80GB/0.5GB)", 1),
                 ("Computer (32-bit/100GB/1GB)", 1),
                 ("Computer (32-bit/120GB/1GB)", 1),
                 ("Computer (64-bit/240GB/2GB)", 1),
                 ("Computer (64-bit/320GB/4GB)", 1))
    printers = (("Laser Printer (4 ppm)", 1),
                ("Laser Printer (6 ppm)", 1),
                ("Laser Printer (8 ppm)", 1),
                ("Laser Printer (16 ppm)", 1))
    chairs = (("Secretary Chair", 2),
              ("Executive Chair (Basic)", 2),
              ("Executive Chair (Ergonimic)", 2),
              ("Executive Chair (Hi-Tech)", 2))
    desks = (("Desk (Basic, 3 drawer)", 2),
             ("Desk (Standard, 3 drawer)", 2),
             ("Desk (Executive, 3 drawer)", 2),
             ("Desk (Executive, 4 drawer)", 2),
             ("Desk (Large, 4 drawer)", 2))
    furniture = (("Filing Cabinet (3 drawer)", 2),
                 ("Filing Cabinet (4 drawer)", 2),
                 ("Filing Cabinet (5 drawer)", 2),
                 ("Bookcase (4 shelves)", 2),
                 ("Bookcase (6 shelves)", 2),
                 ("Table (4 seater)", 2),
                 ("Table (8 seater)", 2),
                 ("Table (12 seater)", 2))
    electrical = (("Fan (3 speed)", 3),
                  ("Fan (5 speed)", 3),
                  ("Photocopier (4 ppm)", 3),
                  ("Photocopier (6 ppm)", 3),
                  ("Photocopier (8 ppm)", 3),
                  ("Shredder", 3))
    query.prepare("INSERT INTO assets (name, categoryid, room) "
                  "VALUES (:name, :categoryid, :room)")
    logQuery = QSqlQuery()
    logQuery.prepare("INSERT INTO logs (assetid, date, actionid) "
                     "VALUES (:assetid, :date, :actionid)")
    assetid = 1
    for i in range(20):
        room = QVariant("{0:02d}{1:02d}".format(
                random.choice(floors), random.randint(1, 62)))
        for name, category in (random.choice(monitors),
                random.choice(computers), random.choice(chairs),
                random.choice(desks), random.choice(furniture)):
            query.bindValue(":name", QVariant(name))
            query.bindValue(":categoryid", QVariant(category))
            query.bindValue(":room", room)
            query.exec_()
            logQuery.bindValue(":assetid", QVariant(assetid))
            when = today.addDays(-random.randint(7, 1500))
            logQuery.bindValue(":date", QVariant(when))
            logQuery.bindValue(":actionid", QVariant(ACQUIRED))
            logQuery.exec_()
            if random.random() > 0.7:
                logQuery.bindValue(":assetid", QVariant(assetid))
                when = when.addDays(random.randint(1, 1500))
                if when <= today:
                    logQuery.bindValue(":date", QVariant(when))
                    logQuery.bindValue(":actionid",
                            QVariant(random.choice((2, 4))))
                    logQuery.exec_()
            assetid += 1
        if random.random() > 0.8:
            name, category = random.choice(printers)
            query.bindValue(":name", QVariant(name))
            query.bindValue(":categoryid", QVariant(category))
            query.bindValue(":room", room)
            query.exec_()
            logQuery.bindValue(":assetid", QVariant(assetid))
            when = today.addDays(-random.randint(7, 1500))
            logQuery.bindValue(":date", QVariant(when))
            logQuery.bindValue(":actionid", QVariant(ACQUIRED))
            logQuery.exec_()
            if random.random() > 0.6:
                logQuery.bindValue(":assetid", QVariant(assetid))
                when = when.addDays(random.randint(1, 1500))
                if when <= today:
                    logQuery.bindValue(":date", QVariant(when))
                    logQuery.bindValue(":actionid",
                            QVariant(random.choice((2, 4))))
                    logQuery.exec_()
            assetid += 1
        if random.random() > 0.6:
            name, category = random.choice(electrical)
            query.bindValue(":name", QVariant(name))
            query.bindValue(":categoryid", QVariant(category))
            query.bindValue(":room", room)
            query.exec_()
            logQuery.bindValue(":assetid", QVariant(assetid))
            when = today.addDays(-random.randint(7, 1500))
            logQuery.bindValue(":date", QVariant(when))
            logQuery.bindValue(":actionid", QVariant(ACQUIRED))
            logQuery.exec_()
            if random.random() > 0.5:
                logQuery.bindValue(":assetid", QVariant(assetid))
                when = when.addDays(random.randint(1, 1500))
                if when <= today:
                    logQuery.bindValue(":date", QVariant(when))
                    logQuery.bindValue(":actionid",
                            QVariant(random.choice((2, 4))))
                    logQuery.exec_()
            assetid += 1
        QApplication.processEvents()

    print("Assets:")
    query.exec_("SELECT id, name, categoryid, room FROM assets "
                "ORDER by id")
    categoryQuery = QSqlQuery()
    while query.next():
        id = query.value(0).toInt()[0]
        name = unicode(query.value(1).toString())
        categoryid = query.value(2).toInt()[0]
        room = unicode(query.value(3).toString())
        categoryQuery.exec_(QString("SELECT name FROM categories "
                "WHERE id = %1").arg(categoryid))
        category = "{0}".format(categoryid)
        if categoryQuery.next():
            category = unicode(categoryQuery.value(0).toString())
        print("{0}: {1} [{2}] {3}".format(id, name, category, room))
    QApplication.processEvents()


class ReferenceDataDlg(QDialog):

    def __init__(self, table, title, parent=None):
        super(ReferenceDataDlg, self).__init__(parent)

        self.model = QSqlTableModel(self)
        self.model.setTable(table)
        self.model.setSort(NAME, Qt.AscendingOrder)
        self.model.setHeaderData(ID, Qt.Horizontal, QVariant("ID"))
        self.model.setHeaderData(NAME, Qt.Horizontal, QVariant("Name"))
        self.model.setHeaderData(DESCRIPTION, Qt.Horizontal,
                                 QVariant("Description"))
        self.model.select()

        self.view = QTableView()
        self.view.setModel(self.model)
        self.view.setSelectionMode(QTableView.SingleSelection)
        self.view.setSelectionBehavior(QTableView.SelectRows)
        self.view.setColumnHidden(ID, True)
        self.view.resizeColumnsToContents()

        addButton = QPushButton("&Add")
        deleteButton = QPushButton("&Delete")
        okButton = QPushButton("&OK")
        if not MAC:
            addButton.setFocusPolicy(Qt.NoFocus)
            deleteButton.setFocusPolicy(Qt.NoFocus)

        buttonLayout = QHBoxLayout()
        buttonLayout.addWidget(addButton)
        buttonLayout.addWidget(deleteButton)
        buttonLayout.addStretch()
        buttonLayout.addWidget(okButton)
        layout = QVBoxLayout()
        layout.addWidget(self.view)
        layout.addLayout(buttonLayout)
        self.setLayout(layout)

        self.connect(addButton, SIGNAL("clicked()"), self.addRecord)
        self.connect(okButton, SIGNAL("clicked()"), self.accept)

        self.setWindowTitle(
                "Asset Manager - Edit {0} Reference Data".format(title))


    def addRecord(self):
        row = self.model.rowCount()
        self.model.insertRow(row)
        index = self.model.index(row, NAME)
        self.view.setCurrentIndex(index)
        self.view.edit(index)


class AssetDelegate(QSqlRelationalDelegate):

    def __init__(self, parent=None):
        super(AssetDelegate, self).__init__(parent)


    def paint(self, painter, option, index):
        myoption = QStyleOptionViewItem(option)
        if index.column() == ROOM:
            myoption.displayAlignment |= (Qt.AlignRight|Qt.AlignVCenter)
        QSqlRelationalDelegate.paint(self, painter, myoption, index)


    def createEditor(self, parent, option, index):
        if index.column() == ROOM:
            editor = QLineEdit(parent)
            regex = QRegExp(r"(?:0[1-9]|1[0124-9]|2[0-7])"
                                   r"(?:0[1-9]|[1-5][0-9]|6[012])")
            validator = QRegExpValidator(regex, parent)
            editor.setValidator(validator)
            editor.setInputMask("9999")
            editor.setAlignment(Qt.AlignRight|Qt.AlignVCenter)
            return editor
        else:
            return QSqlRelationalDelegate.createEditor(self, parent,
                                                       option, index)

    def setEditorData(self, editor, index):
        if index.column() == ROOM:
            text = index.model().data(index, Qt.DisplayRole).toString()
            editor.setText(text)
        else:
            QSqlRelationalDelegate.setEditorData(self, editor, index)


    def setModelData(self, editor, model, index):
        if index.column() == ROOM:
            model.setData(index, QVariant(editor.text()))
        else:
            QSqlRelationalDelegate.setModelData(self, editor, model,
                                                index)


class LogDelegate(QSqlRelationalDelegate):

    def __init__(self, parent=None):
        super(LogDelegate, self).__init__(parent)


    def paint(self, painter, option, index):
        myoption = QStyleOptionViewItem(option)
        if index.column() == DATE:
            myoption.displayAlignment |= (Qt.AlignRight|Qt.AlignVCenter)
        QSqlRelationalDelegate.paint(self, painter, myoption, index)


    def createEditor(self, parent, option, index):
        if (index.column() == ACTIONID and
            index.model().data(index, Qt.DisplayRole).toInt()[0] ==
            ACQUIRED): # Acquired is read-only
            return
        if index.column() == DATE:
            editor = QDateEdit(parent)
            editor.setMaximumDate(QDate.currentDate())
            editor.setDisplayFormat("yyyy-MM-dd")
            if PYQT_VERSION_STR >= "4.1.0":
                editor.setCalendarPopup(True)
            editor.setAlignment(Qt.AlignRight|
                                Qt.AlignVCenter)
            return editor
        else:
            return QSqlRelationalDelegate.createEditor(self, parent,
                                                       option, index)

    def setEditorData(self, editor, index):
        if index.column() == DATE:
            date = index.model().data(index, Qt.DisplayRole).toDate()
            editor.setDate(date)
        else:
            QSqlRelationalDelegate.setEditorData(self, editor, index)


    def setModelData(self, editor, model, index):
        if index.column() == DATE:
            model.setData(index, QVariant(editor.date()))
        else:
            QSqlRelationalDelegate.setModelData(self, editor, model,
                                                index)


class MainForm(QDialog):

    def __init__(self):
        super(MainForm, self).__init__()

        self.assetModel = QSqlRelationalTableModel(self)
        self.assetModel.setTable("assets")
        self.assetModel.setRelation(CATEGORYID,
                QSqlRelation("categories", "id", "name"))
        self.assetModel.setSort(ROOM, Qt.AscendingOrder)
        self.assetModel.setHeaderData(ID, Qt.Horizontal, QVariant("ID"))
        self.assetModel.setHeaderData(NAME, Qt.Horizontal,
                QVariant("Name"))
        self.assetModel.setHeaderData(CATEGORYID, Qt.Horizontal,
                QVariant("Category"))
        self.assetModel.setHeaderData(ROOM, Qt.Horizontal,
                QVariant("Room"))
        self.assetModel.select()

        self.assetView = QTableView()
        self.assetView.setModel(self.assetModel)
        self.assetView.setItemDelegate(AssetDelegate(self))
        self.assetView.setSelectionMode(QTableView.SingleSelection)
        self.assetView.setSelectionBehavior(QTableView.SelectRows)
        self.assetView.setColumnHidden(ID, True)
        self.assetView.resizeColumnsToContents()
        assetLabel = QLabel("A&ssets")
        assetLabel.setBuddy(self.assetView)

        self.logModel = QSqlRelationalTableModel(self)
        self.logModel.setTable("logs")
        self.logModel.setRelation(ACTIONID,
                QSqlRelation("actions", "id", "name"))
        self.logModel.setSort(DATE, Qt.AscendingOrder)
        self.logModel.setHeaderData(DATE, Qt.Horizontal, QVariant("Date"))
        self.logModel.setHeaderData(ACTIONID, Qt.Horizontal,
                QVariant("Action"))
        self.logModel.select()

        self.logView = QTableView()
        self.logView.setModel(self.logModel)
        self.logView.setItemDelegate(LogDelegate(self))
        self.logView.setSelectionMode(QTableView.SingleSelection)
        self.logView.setSelectionBehavior(QTableView.SelectRows)
        self.logView.setColumnHidden(ID, True)
        self.logView.setColumnHidden(ASSETID, True)
        self.logView.resizeColumnsToContents()
        self.logView.horizontalHeader().setStretchLastSection(True)
        logLabel = QLabel("&Logs")
        logLabel.setBuddy(self.logView)

        editActionsButton = QPushButton("&Edit Actions...")
        editCategoriesButton = QPushButton("Ed&it Categories...")
        quitButton = QPushButton("&Quit")
        for button in (editActionsButton, editCategoriesButton, quitButton):
            if MAC:
                button.setDefault(False)
                button.setAutoDefault(False)
            else:
                button.setFocusPolicy(Qt.NoFocus)

        dataLayout = QVBoxLayout()
        dataLayout.addWidget(assetLabel)
        dataLayout.addWidget(self.assetView, 1)
        dataLayout.addWidget(logLabel)
        dataLayout.addWidget(self.logView)
        buttonLayout = QVBoxLayout()
        buttonLayout.addWidget(editActionsButton)
        buttonLayout.addWidget(editCategoriesButton)
        buttonLayout.addStretch()
        buttonLayout.addWidget(quitButton)
        layout = QHBoxLayout()
        layout.addLayout(dataLayout, 1)
        layout.addLayout(buttonLayout)
        self.setLayout(layout)

        self.connect(self.assetView.selectionModel(),
                SIGNAL(("currentRowChanged(QModelIndex,QModelIndex)")),
                self.assetChanged)
        self.connect(editActionsButton, SIGNAL("clicked()"),
                     self.editActions)
        self.connect(editCategoriesButton, SIGNAL("clicked()"),
                     self.editCategories)
        self.connect(quitButton, SIGNAL("clicked()"), self.done)

        self.assetChanged(self.assetView.currentIndex())
        self.setMinimumWidth(650)
        self.setWindowTitle("Asset Manager")


    def done(self, result=1):
        query = QSqlQuery()
        query.exec_("DELETE FROM logs WHERE logs.assetid NOT IN"
                    "(SELECT id FROM assets)")
        QDialog.done(self, 1)


    def assetChanged(self, index):
        if index.isValid():
            record = self.assetModel.record(index.row())
            id = record.value("id").toInt()[0]
            self.logModel.setFilter(QString("assetid = %1").arg(id))
        else:
            self.logModel.setFilter("assetid = -1")
        self.logModel.reset() # workaround for Qt <= 4.3.3/SQLite bug
        self.logModel.select()
        self.logView.horizontalHeader().setVisible(
                self.logModel.rowCount() > 0)
        if PYQT_VERSION_STR < "4.1.0":
            self.logView.setColumnHidden(ID, True)
            self.logView.setColumnHidden(ASSETID, True)


    def addAsset(self):
        row = (self.assetView.currentIndex().row()
               if self.assetView.currentIndex().isValid() else 0)

        QSqlDatabase.database().transaction()
        self.assetModel.insertRow(row)
        index = self.assetModel.index(row, NAME)
        self.assetView.setCurrentIndex(index)

        assetid = 1
        query = QSqlQuery()
        query.exec_("SELECT MAX(id) FROM assets")
        if query.next():
            assetid = query.value(0).toInt()[0]
        query.prepare("INSERT INTO logs (assetid, date, actionid) "
                      "VALUES (:assetid, :date, :actionid)")
        query.bindValue(":assetid", QVariant(assetid + 1))
        query.bindValue(":date", QVariant(QDate.currentDate()))
        query.bindValue(":actionid", QVariant(ACQUIRED))
        query.exec_()
        QSqlDatabase.database().commit()
        self.assetView.edit(index)


    def addAction(self):
        index = self.assetView.currentIndex()
        if not index.isValid():
            return
        QSqlDatabase.database().transaction()
        record = self.assetModel.record(index.row())
        assetid = record.value(ID).toInt()[0]

        row = self.logModel.rowCount()
        self.logModel.insertRow(row)
        self.logModel.setData(self.logModel.index(row, ASSETID),
                              QVariant(assetid))
        self.logModel.setData(self.logModel.index(row, DATE),
                              QVariant(QDate.currentDate()))
        QSqlDatabase.database().commit()
        index = self.logModel.index(row, ACTIONID)
        self.logView.setCurrentIndex(index)
        self.logView.edit(index)


    def editActions(self):
        form = ReferenceDataDlg("actions", "Action", self)
        form.exec_()


    def editCategories(self):
        form = ReferenceDataDlg("categories", "Category", self)
        form.exec_()


def main():
    app = QApplication(sys.argv)

    filename = os.path.join(os.path.dirname(__file__), "assetsdb.db")
    create = not QFile.exists(filename)
    db = QSqlDatabase.addDatabase("QSQLITE")
    db.setDatabaseName(filename)
    if not db.open():
        QMessageBox.warning(None, "Asset Manager",
            QString("Database Error: %1")
            .arg(db.lastError().text()))
        sys.exit(1)

    if create:
        createFakeData()

    form = MainForm()
    form.show()
    if create:
        app.processEvents()
        app.restoreOverrideCursor()
    app.exec_()
    del form
    del db

我最近检查了Mark Summerfield的“使用Python和Qt进行快速GUI编程”第15章中的示例，该示例介绍了SQL数据库TableView建模的用法。在此原始示例中，...

Answer 1

我想出于效率的原因，每次显示QComboBox时都不会为与QSqlRelationalDelegate的QComboBox相关的模型重新充电，解决方案是使用select()方法重新加载该模型：