QAssociativeIterable Class

The QAssociativeIterable class is an iterable interface for an associative container in a QVariant. More...

Header: #include <QAssociativeIterable>
qmake: QT += core
Since: Qt 5.2

This class was introduced in Qt 5.2.

Public Types

Public Functions

QAssociativeIterable::const_iterator begin() const
QAssociativeIterable::const_iterator end() const
QAssociativeIterable::const_iterator find(const QVariant &key) const
int size() const
QVariant value(const QVariant &key) const

Detailed Description

This class allows several methods of accessing the elements of an associative container held within a QVariant. An instance of QAssociativeIterable can be extracted from a QVariant if it can be converted to a QVariantHash or QVariantMap.


  QHash<int, QString> mapping;
  mapping.insert(7, "Seven");
  mapping.insert(11, "Eleven");
  mapping.insert(42, "Forty-two");

  QVariant variant = QVariant::fromValue(mapping);
  if (variant.canConvert<QVariantHash>()) {
      QAssociativeIterable iterable = variant.value<QAssociativeIterable>();
      // Can use foreach over the values:
      foreach (const QVariant &v, iterable) {
          qDebug() << v;
      }
      // Can use C++11 range-for over the values:
      for (const QVariant &v : iterable) {
          qDebug() << v;
      }
      // Can use iterators:
      QAssociativeIterable::const_iterator it = iterable.begin();
      const QAssociativeIterable::const_iterator end = iterable.end();
      for ( ; it != end; ++it) {
          qDebug() << *it; // The current value
          qDebug() << it.key();
          qDebug() << it.value();
      }
  }

The container itself is not copied before iterating over it.

See also QVariant.

Member Function Documentation

QAssociativeIterable::const_iterator QAssociativeIterable::begin() const

Returns a QAssociativeIterable::const_iterator for the beginning of the container. This can be used in stl-style iteration.

See also end().

QAssociativeIterable::const_iterator QAssociativeIterable::end() const

Returns a QAssociativeIterable::const_iterator for the end of the container. This can be used in stl-style iteration.

See also begin().

QAssociativeIterable::const_iterator QAssociativeIterable::find(const QVariant &key) const

Returns a QAssociativeIterable::const_iterator for the given key key in the container, if the types are convertible.

If the key is not found, returns end().

This can be used in stl-style iteration.

This function was introduced in Qt 5.5.

See also begin(), end(), and value().

int QAssociativeIterable::size() const

Returns the number of elements in the container.

QVariant QAssociativeIterable::value(const QVariant &key) const

Returns the value for the given key in the container, if the types are convertible.

See also find().