c++ - Qt - 在 QSignalMapper 调用的函数中更新

Question

我有一个 QTreeWidget，其中它的每个项目在一列中都有一个 QComboBox。我已将它连接到带有 QSignalMapper 的插槽，并且在触发时成功检索了组合框中的项目和索引。我是这样做的:

foreach(Workplace *wp, allWorkplaces){
        QTreeWidgetItem *workplaceItem = new QTreeWidgetItem;

        workplaceItem->setText(0, wp->workplaceName());
        workplaceItem->setText(1, wp->workplaceDescription());

        myWorkplaceUi->treeWidget->addTopLevelItem(workplaceItem);

        QComboBox *combo = new QComboBox();

        combo->addItems(allShiftModels);

        combo->setAutoFillBackground(true);

        ShiftModel *shiftModel = qobject_cast<ShiftModel *>(wp->usedShiftModel);

        myWorkplaceUi->treeWidget->setItemWidget(workplaceItem,2, combo);

        if(shiftModel && !shiftModel->shiftModelName().isEmpty()){
            qDebug()<<"after the cast: "<< shiftModel->shiftModelName();
            combo->setCurrentIndex(combo->findText(shiftModel->shiftModelName(), Qt::MatchExactly));
        }else{
            combo->setCurrentIndex(combo->findText("None", Qt::MatchExactly));
        }

        connect(combo, SIGNAL(currentIndexChanged(int)), signalMapper, SLOT(map()));
        signalMapper->setMapping(combo, QString("%1").arg(wp->workplaceName()));
    }

    connect(signalMapper, SIGNAL(mapped(const QString &)),this, SLOT(changed(const QString &)));

我的目标是，在检索到 Workplace 和 ShiftModel 之后，在我已经创建的 Workplaces 的实例中更新它们。所以，基本上，我尝试找到所选的 Workplace 和 ShiftModel，因为根据所选的 ShiftModel，我将更改指向 Workplace 类中的 ShiftModel 的指针:

class Workplace : public QObject
{
    Q_OBJECT

public:
    (...)
    ShiftModel *usedShiftModel;
    (...)
}

改变了槽:

void workplacesdialog::changed(QString position){

    QList<Workplace* > allWorkplaces = this->myProject->listMyWorkplaces();
    QList<ShiftModel*> allShiftModels = this->myProject->myFactory->listShiftModels();

    foreach(Workplace* workplace, allWorkplaces){
        foreach(ShiftModel *shiftmodel, allShiftModels){
            qDebug() <<"workplace:"<< workplace->workplaceName();
            qDebug() <<"shiftmodel:"<< shiftmodel->shiftModelName();

            QString wp = position;
            QTreeWidgetItem* item=(QTreeWidgetItem*)myWorkplaceUi->treeWidget->findItems(wp,Qt::MatchExactly,0).at(0);
            QComboBox *combo = (QComboBox*)myWorkplaceUi->treeWidget->itemWidget(item,2);
            if(combo && item){
                QString sm = combo->currentText();

                qDebug() << "selected shiftmodel "<< sm << " on workplace "<< wp;

                        if(workplace->workplaceName()==wp && shiftmodel->shiftModelName()==sm){
                            workplace->usedShiftModel = shiftmodel;
                            break;
                        }
                        else{
                            workplace->usedShiftModel = 0;
                            return;
                        }

            }else{
                qDebug() << "cast failed!";
                return;
            }
        }
    }
}

所以，我的问题是，当我单击其中一个组合框时，成功检索了所选的项目和索引，但是随后，当我尝试使用中的两个 foreach 循环遍历它们时插槽，它没有像我预期的那样工作。我希望每次我单击其中一个组合框中的索引时，都会调用它，而且确实如此。尽管出于某种原因，我用来将用户选择的内容与已实例化的内容相匹配的方法不起作用。

另外，看起来它只命中 allWorkplaces 列表中的第一个 workplace 以及 中的第一个 shiftmodel >ShiftModels 列表，这是我的问题。

如果有人知道如何解决这个问题或有任何想法要分享，请告诉我。谢谢。

Answer 1

问题是这样的:

if(workplace->workplaceName()==wp && shiftmodel->shiftModelName()==sm){
    workplace->usedShiftModel = shiftmodel;
    break;
}
else{
    workplace->usedShiftModel = 0;
    return;
}

如果工作场所名称不匹配，或者类次模型名称不匹配，工作地点与其当前链接的类次模型之间的关系将被删除，您的函数将返回。

我可以为您重构这两个 for 循环，但还有一种更简单且不易出错的方法:

注意:我用“TODO”标记了一些代码路径，由于时间不够，我跳过了这些路径。不过，您应该能够自己弄清楚它们。

// Set up hashes for quick lookup
QHash< QString, Workplace* > workplaceHash;

QList<Workplace* > allWorkplaces = this->myProject->listMyWorkplaces();
foreach( Workplace* workplace, allWorkplaces )
{
    workplaceHash.insert( workplace, workplace->workplaceName() );
}

// TODO: Do a similar thing for the shift models here

// Find the selected workplace
if( !workplaceHash.contains( position ) )
{
    // TODO: Error handling (An unknown/No workplace was selected)
    return;
}
// else: A valid workplace was selected

Workplace* selectedWorkplace = workplaceHash.value( position );

// TODO: Retrieve the name of the shift model (stored in variable sm)

// Find the selected shiftmodel
if( !shiftplaceHash.contains( sm ) )
{
    // No shift model was selected
    selectedWorkplace->usedShiftModel= 0;
    return;
}
// Else: Both work place and shift model were selected

Shiftplace* selectedShiftModel = shiftplaceHash.value( sm );

selectedWorkplace->usedShiftModel = selectedShiftModel;

一些重构的想法:

• 您可以在此方法之外创建散列并将它们存储在成员变量中。只需确保在添加或删除工作场所时始终更新哈希。
• 您可以通过将部分代码提取到单独的方法中来更容易地发现错误，例如QString getSelectedShiftModelName() 等