Qt从QString动态创建QWidget

Question

I am trying to create a program that reads information from a database, and accordingly set up the layout. Specifically, I want to read two date fields and depending on the difference between the days, create a day(s) number of elements. Have anyone got an idea on how this could be done? I have tried to create an element using the QString->text() property with no success for obvious reasons and I have managed to write a function to create an element, but my problem is that I cannot control the name of the element, making it impossible for me with my rubbish knowledge about c++ to then interact with the given element.

Thank you for your time,

Cheers.

Answer 1

I think a QHash would be the perfect tool for your needs. It allows storing and lookup of pretty much anything through a unique key. That means you can store the widgets with their title as a key and then later retrieve a widget with a certain title from that hash.

Here is how to define such a hash:

// .h file
#include <QtCore/QHash>
#include <QtGui/QWidget>

class MyWidget : public QWidget
{
    // ...
private:
    QHash< QString, QWidget* > m_dynamicWidgetHash;
};

The Widgets (or any QWidget subclass) can then be stored in the hash like this, assuming the titles will always be unique :

// .cpp file
void MyWidget::someMethod()
{
    QList< QString > widgetTitles = getWidgetTitlesFromSomewhere();

    foreach( QString title, widgetTitles )
    {
        SomeWidgetSubclass* widget = new SomeWidgetSubclass( this );
        widget->setTitle( title );
        // Note: This will not work if two widgets can have the same title
        Q_ASSERT( !m_dynamicWidgetHash.contains( title ) );
        m_dynamicWidgetHash.insert( title, widget );
    }
}

You can then later find your widgets knowing only the name like this:

// .cpp file
void MyWidget::someOtherMethod( const QString& title )
{
    SomeWidgetSubclass* widget = m_dynamicWidgetHash.value( title );
    if( !widget )
    {
        // TODO: Error Handling
        return;
    }

    // Do whatever you want with the widget here
}

Answer 2

Also, it might be interested for you how to create object by class name using QMetaType . There is QMetaType::construct method. It requires that qRegisterMetaType function is should be called before. Detaild description is here .