Qt : Find object in list by property

Question

i'm a beginner in Qt, I'm more used to programming in C#. So my question is how to implement in Qt the C# code bellow:

public class MyObject 
{    
    private string myproperty;

    public string Myproperty 
    {
                get { return myproperty; }
                set { myproperty = value; }
    }    
}

private void button1_Click(object sender, EventArgs e) 
{
    List<MyObject> myobjectlist = new List<MyObject>();

    MyObject selectedobject = myobjectlist.Find(p => p.Myproperty == "Some name");               
}

is it possible in Qt retrieve a object from list like the code above?

Answer 1

This has little to do with Qt itself. If you can use C++11, use a lambda, just like in C#:

auto itObj = std::find_if(
  myobjectlist.begin(), myobjectlist.end(),
  [](MyObject o) { return o.myproperty() == "Some name"; }
);
if (itObj != myobjectlist.end())
{
  // object was found, use *itObj (or itObj->) to access it/its members
}
else
{
  // object was not found
}

Without C++11, you'd have to hand-create a class with operator() to use as the predicate, or write a for loop by hand.

Answer 2

Maybe this way?

void MyClass::button1_Click() 
{
    QList<MyObject> myobjectlist;
    MyObject selectedobject;
    foreach (const MyObject &o, myobjectlist) {
        if (o.property("Some name").isValid()) {
            selectedobject = o;
            break;        
        }
    }
}

Assuming that the MyObject is a QObject.

Answer 3

Add to .pro file CONFIG +=c++11

#include <QString>
#include <QList>
#include <algorithm>
//...
//...
class MyObject
{
private:
    QString myproperty;
public:

   void MypropertySet(QString s)
   {
       myproperty=s;
   }
   QString MypropertyGet() const
   {
       return myproperty;
   }
};



void MainWindow::on_pushButton_clicked()
{
    QList<MyObject> myobjectlist;
    MyObject selectedobject=*std::find_if(myobjectlist.begin(), myobjectlist.end(),[] (const MyObject& s) { return s.MypropertyGet()=="Some name"; });

}

Main window has a button and when you click it a privete slot from main window is called on_pushButton_clicked(). If you have more questions i can post whole files. If you are not sure that the object you are looking for is in the list then you have to check if you found it.