PyQt5编程(46)—使用数据库(12)

5. QDataWidgetMapper类
QDataWidgetMapper类提供了数据模型部分数据与部件之间的映射。
可以使用QDataWidgetMapper创建与模型某项数据关联的感知组件。 如果方向是水平的（默认），则数据是模型的列数据，否则是行数据。
当前索引改变时，每个关联组件会被来自模型的数据更新。 如果用户编辑了组件的内容，这些更改也会写回模型中。 使用addMapping()实现组件和模型数据之间的映射。

addMapping(QWidget widget, int section)
addMapping(QWidget widget, int section, QByteArray propertyName)，Qt 4.3中增加的，允许指定传输数据的属性(propertyName)。

下列代码是以phonelog.db数据库，使用该类的示例：

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("第一条")
    prevButton = QPushButton("前一条")
    nextButton = QPushButton("后一条")
    lastButton = QPushButton("最后一条")
    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()

运行结果：

图片.png