QDataWidgetMapper、QSqlRelationalTableModel、mapper不会提交 我面对一个C++ QT4控件的问题。此小部件用于将行添加到SQLite数据库中。以下是我面临的问题中使用的数据库表： CREATE TABLE 'statuses' ('id' INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL UNIQUE , 'name' VARCHAR(50) NOT NULL UNIQUE , 'bgcolor' VARCHAR(6) NOT NULL DEFAULT ffffff, 'fgcolor' VARCHAR(6) NOT NULL DEFAULT 000000) CREATE TABLE 'addresses' ('id' INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL UNIQUE , 'name' VARCHAR(50) NOT NULL UNIQUE , 'country' VARCHAR(25), 'town' VARCHAR(50), 'postal_code' VARCHAR(10), 'street' TEXT check(typeof('street') = 'text') , 'ref' VARCHAR(5) NOT NULL , 'status_id' INTEGER NOT NULL, FOREIGN KEY(status_id) REFERENCES statuses(id))

我编写的代码完全遵循Qt教程，如下所示：

CreateAddressDialog::CreateAddressDialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::CreateAddressDialog)
{
    ui->setupUi(this);
    /* Set up "buddies" */
    ui->nameLabel->setBuddy(ui->nameLineEdit);
    ui->refLabel->setBuddy(ui->refLineEdit);
    ui->townLabel->setBuddy(ui->townLineEdit);
    ui->streetLabel->setBuddy(ui->streetLineEdit);
    ui->countryLabel->setBuddy(ui->countryLineEdit);
    ui->postalCodeLabel->setBuddy(ui->postalCodeLineEdit);
    ui->statusLabel->setBuddy(ui->statusCB);

    /* Set up status model */
    ui->statusCB->clear();
    statusModel = new QSqlRelationalTableModel(this, backbone::instance()->db);
    statusModel->setEditStrategy(QSqlTableModel::OnManualSubmit);
    statusModel->setTable("addresses");
    int statusFieldId = statusModel->fieldIndex("status_id");
    /***** Warning: after next instruction fieldIndex('status_id') will return -1. */
    statusModel->setRelation(statusFieldId,QSqlRelation("statuses", "id", "name"));
    statusModel->select();
    relModel = statusModel->relationModel(statusFieldId);
    ui->statusCB->setModel(relModel);
    ui->statusCB->setModelColumn(relModel->fieldIndex("name"));
    mapper = new QDataWidgetMapper(this);
    mapper->setItemDelegate(new QSqlRelationalDelegate(this));
    mapper->setModel(statusModel);
    mapper->addMapping(ui->refLineEdit, statusModel->fieldIndex("ref"));
    mapper->addMapping(ui->nameLineEdit, statusModel->fieldIndex("name"));
    mapper->addMapping(ui->statusCB, statusFieldId);
}

提交过程如下所示：

void CreateAddressDialog::accept()
{
    if(ui->nameLineEdit->text().length() < 5){
        QMessageBox::critical(0, tr("Error"),tr("The name must be at least 5 characters long."), QMessageBox::Cancel);
        return;
    }else if(ui->refLineEdit->text().length() > 10){
        QMessageBox::critical(0, tr("Error"),tr("The reference may not be more than 10 characters long."), QMessageBox::Cancel);
        return;
    }else if(ui->statusCB->currentIndex() < 0){
        QMessageBox::critical(0, tr("Error"),tr("The item must have a status."), QMessageBox::Cancel);
        return;
    }
    qDebug() << mapper->submit();
    this->close();
}

问题是，将显示mapper->submit failed false。如果调用模型的lastError，则不会显示任何内容。映射到此映射器的字段是表id的必填字段，但被标记为自动增量的字段除外

非常感谢您提供的任何帮助，因为我真的不明白，而且似乎无法找到为什么这个小部件没有向数据库添加任何内容。请允许我提到，我使用标准的SQLite数据库查看器进行了检查，以确保SQLite数据库的内容如下

备注：您可以浏览完整代码以供参考，网址为

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提前谢谢

试着用submitAll代替submit。

虽然这个问题很老了，但我几天前也经历过同样的事情

statusModel->setEditStrategy(QSqlTableModel::OnManualSubmit);

行的manualsubmit参数迫使您手动将内容提交到数据库。因此，要对数据库进行更改，我必须在调用mapper->submit之后调用statusModel->submitAll。

请参阅有关编写更好、更有用的答案的指导原则。