PyQt5編程(46)—使用數(shù)據(jù)庫(12)

5. QDataWidgetMapper類
QDataWidgetMapper類提供了數(shù)據(jù)模型部分數(shù)據(jù)與部件之間的映射拙毫。
可以使用QDataWidgetMapper創(chuàng)建與模型某項數(shù)據(jù)關聯(lián)的感知組件胆建。 如果方向是水平的（默認），則數(shù)據(jù)是模型的列數(shù)據(jù)洞渔，否則是行數(shù)據(jù)叹誉。
當前索引改變時凛膏，每個關聯(lián)組件會被來自模型的數(shù)據(jù)更新。 如果用戶編輯了組件的內(nèi)容，這些更改也會寫回模型中稠肘。 使用addMapping()實現(xiàn)組件和模型數(shù)據(jù)之間的映射。

addMapping(QWidget widget, int section)
addMapping(QWidget widget, int section, QByteArray propertyName)萝毛，Qt 4.3中增加的项阴，允許指定傳輸數(shù)據(jù)的屬性(propertyName)。

下列代碼是以phonelog.db數(shù)據(jù)庫笆包，使用該類的示例：

import os
import sys
from PyQt5.QtCore import (QDate, QDateTime, QFile, QVariant, Qt)
from PyQt5.QtWidgets import (QApplication, QDataWidgetMapper,QComboBox,
QDateTimeEdit, QDialog, QGridLayout, QHBoxLayout, QLabel,
QLineEdit, QMessageBox, QPushButton, QVBoxLayout)
from PyQt5.QtSql import (QSqlDatabase, QSqlQuery, QSqlRelation,
QSqlRelationalDelegate, QSqlRelationalTableModel)

DATETIME_FORMAT = "yyyy-MM-dd hh:mm"

class PhoneLogDlg(QDialog):

FIRST, PREV, NEXT, LAST = range(4)

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

    callerLabel = QLabel("&Caller:")
    self.callerEdit = QLineEdit()
    callerLabel.setBuddy(self.callerEdit)
    today = QDate.currentDate()
    startLabel = QLabel("&Start:")
    self.startDateTime = QDateTimeEdit()
    startLabel.setBuddy(self.startDateTime)
    self.startDateTime.setDateRange(today, today)
    self.startDateTime.setDisplayFormat(DATETIME_FORMAT)
    endLabel = QLabel("&End:")
    self.endDateTime = QDateTimeEdit()
    endLabel.setBuddy(self.endDateTime)
    self.endDateTime.setDateRange(today, today)
    self.endDateTime.setDisplayFormat(DATETIME_FORMAT)
    topicLabel = QLabel("&Topic:")
    topicEdit = QLineEdit()
    topicLabel.setBuddy(topicEdit)
    outcomeLabel = QLabel("&Outcome:")
    self.outcomeComboBox = QComboBox()
    outcomeLabel.setBuddy(self.outcomeComboBox)
    firstButton = QPushButton("第一條")
    prevButton = QPushButton("前一條")
    nextButton = QPushButton("后一條")
    lastButton = QPushButton("最后一條")
    adon = QPushButton("&Add")
    deleteButton = QPushButton("&Delete")
    quitButton = QPushButton("&Quit")
    adon.setFocusPolicy(Qt.NoFocus)
    deleteButton.setFocusPolicy(Qt.NoFocus)

    fieldLayout = QGridLayout()
    fieldLayout.addWidget(callerLabel, 0, 0)
    fieldLayout.addWidget(self.callerEdit, 0, 1, 1, 3)
    fieldLayout.addWidget(startLabel, 1, 0)
    fieldLayout.addWidget(self.startDateTime, 1, 1)
    fieldLayout.addWidget(endLabel, 1, 2)
    fieldLayout.addWidget(self.endDateTime, 1, 3)
    fieldLayout.addWidget(topicLabel, 2, 0)
    fieldLayout.addWidget(topicEdit, 2, 1, 1, 3)
    fieldLayout.addWidget(outcomeLabel, 3, 0)
    fieldLayout.addWidget(self.outcomeComboBox, 3, 1, 1, 3)
    navigationLayout = QHBoxLayout()
    navigationLayout.addWidget(firstButton)
    navigationLayout.addWidget(prevButton)
    navigationLayout.addWidget(nextButton)
    navigationLayout.addWidget(lastButton)
    fieldLayout.addLayout(navigationLayout, 4, 0, 1, 2)
    buttonLayout = QVBoxLayout()
    buttonLayout.addWidget(adon)
    buttonLayout.addWidget(deleteButton)
    buttonLayout.addStretch()
    buttonLayout.addWidget(quitButton)
    layout = QHBoxLayout()
    layout.addLayout(fieldLayout)
    layout.addLayout(buttonLayout)
    self.setLayout(layout)

    self.model = QSqlRelationalTableModel(self)
    self.model.setTable("calls")
    self.model.setRelation(5,
            QSqlRelation("outcomes", "id", "name"))
    self.model.setSort(2, Qt.AscendingOrder)
    self.model.select()

    self.mapper = QDataWidgetMapper(self)
    self.mapper.setSubmitPolicy(QDataWidgetMapper.ManualSubmit)
    self.mapper.setModel(self.model)
    self.mapper.setItemDelegate(QSqlRelationalDelegate(self))
    self.mapper.addMapping(self.callerEdit, 1)
    self.mapper.addMapping(self.startDateTime, 2)
    self.mapper.addMapping(self.endDateTime, 3)
    self.mapper.addMapping(topicEdit, 4)
    relationModel = self.model.relationModel(5)
    self.outcomeComboBox.setModel(relationModel)
    self.outcomeComboBox.setModelColumn(relationModel.fieldIndex("name"))
    self.mapper.addMapping(self.outcomeComboBox, 5)
    self.mapper.toFirst()

    firstButton.clicked.connect(lambda: self.saveRecord(PhoneLogDlg.FIRST))
    prevButton.clicked.connect(lambda: self.saveRecord(PhoneLogDlg.PREV))
    nextButton.clicked.connect(lambda: self.saveRecord(PhoneLogDlg.NEXT))
    lastButton.clicked.connect(lambda: self.saveRecord(PhoneLogDlg.LAST))        
    adon.clicked.connect(self.addRecord)
    deleteButton.clicked.connect(self.deleteRecord)        
    quitButton.clicked.connect(self.done)
    self.setWindowTitle("Phone Log")


def done(self, result=None):
    self.mapper.submit()
    QDialog.done(self, True)


def addRecord(self):
    row = self.model.rowCount()
    self.mapper.submit()
    self.model.insertRow(row)
    self.mapper.setCurrentIndex(row)
    now = QDateTime.currentDateTime()
    self.startDateTime.setDateTime(now)
    self.endDateTime.setDateTime(now)
    self.outcomeComboBox.setCurrentIndex(
            self.outcomeComboBox.findText("Unresolved"))
    self.callerEdit.setFocus()


def deleteRecord(self):
    caller = self.callerEdit.text()
    starttime = self.startDateTime.dateTime().toString(
                                        DATETIME_FORMAT)
    if (QMessageBox.question(self,
            "Delete",
            "Delete call made by

{0} on {1}?".format(caller,starttime),
QMessageBox.Yes|QMessageBox.No) ==
QMessageBox.No):
return
row = self.mapper.currentIndex()
self.model.removeRow(row)
self.model.submitAll()
self.model.select()
if row + 1 >= self.model.rowCount():
row = self.model.rowCount() - 1
self.mapper.setCurrentIndex(row)

def saveRecord(self, where):
    row = self.mapper.currentIndex()
    self.mapper.submit()
    if where == PhoneLogDlg.FIRST:
        row = 0
    elif where == PhoneLogDlg.PREV:
        row = 0 if row <= 1 else row - 1
    elif where == PhoneLogDlg.NEXT:
        row += 1
        if row >= self.model.rowCount():
            row = self.model.rowCount() - 1
    elif where == PhoneLogDlg.LAST:
        row = self.model.rowCount() - 1
    self.mapper.setCurrentIndex(row)

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

filename = os.path.join(os.path.dirname(__file__), "phonelog.db")
db = QSqlDatabase.addDatabase("QSQLITE")
db.setDatabaseName(filename)
if not db.open():
    QMessageBox.warning(None, "Phone Log",
        QString("Database Error: %1").arg(db.lastError().text()))
    sys.exit(1)

form = PhoneLogDlg()
form.show()
sys.exit(app.exec_())

main()

運行結果：

圖片.png