QMetaAssociation::Iterable Class | Qt Core | Qt 6.11.2
Description: QMetaAssociation::Iterable is an iterable interface for an associative container in a QVariant.

- Qt 6.11
- Qt Core
- C++ Classes
- Iterable
- Qt 6.11.2 Reference Documentation

# QMetaAssociation::Iterable Class

class QMetaAssociation::Iterable

QMetaAssociation::Iterable is an iterable interface for an associative container in a QVariant. More...

This class was introduced in Qt 6.11.

- List of all members, including inherited members

## Public Types

`(since 6.11)` class | ConstIterator
`(since 6.11)` class | Iterator
| BidirectionalConstIterator
| BidirectionalIterator
| ForwardConstIterator
| ForwardIterator
| InputConstIterator
| InputIterator
| RandomAccessConstIterator
| RandomAccessIterator

## Public Functions

bool | containsKey(const QVariant &key) const
QMetaAssociation::Iterable::ConstIterator | find(const QVariant &key) const
void | insertKey(const QVariant &key)
QMetaAssociation::Iterable::Iterator | mutableFind(const QVariant &key)
void | removeKey(const QVariant &key)
void | setValue(const QVariant &key, const QVariant &mapped)
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 QMetaAssociation::Iterable can be extracted from a QVariant if it can be converted to a QVariantHash or QVariantMap or if a custom mutable view has been registered.

     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>()) {
         QMetaAssociation::Iterable iterable = variant.value<QMetaAssociation::Iterable>();
         // Can use C++11 range-for over the values:
         for (const QVariant &v : iterable) {
             qDebug() << v;
         }
         // Can use iterators:
         QMetaAssociation::Iterable::const_iterator it = iterable.begin();
         const QMetaAssociation::Iterable::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 Type Documentation

### `[alias]` Iterable::BidirectionalConstIterator

Exposes a const_iterator using std::bidirectional_iterator_tag.

### `[alias]` Iterable::BidirectionalIterator

Exposes an iterator using std::bidirectional_iterator_tag.

### `[alias]` Iterable::ForwardConstIterator

Exposes a const_iterator using std::forward_iterator_tag.

### `[alias]` Iterable::ForwardIterator

Exposes an iterator using std::forward_iterator_tag.

### `[alias]` Iterable::InputConstIterator

Exposes a const_iterator using std::input_iterator_tag.

### `[alias]` Iterable::InputIterator

Exposes an iterator using std::input_iterator_tag.

### `[alias]` Iterable::RandomAccessConstIterator

Exposes a const_iterator using std::random_access_iterator_tag.

### `[alias]` Iterable::RandomAccessIterator

Exposes an iterator using std::random_access_iterator_tag.

## Member Function Documentation

### bool Iterable::containsKey(const QVariant &key) const

Returns `true` if the container has an entry with the given key, or `false` otherwise. If the key isn't convertible to the expected type, `false` is returned.

### QMetaAssociation::Iterable::ConstIterator Iterable::find(const QVariant &key) const

Retrieves a ConstIterator pointing to the element at the given key, or the end of the container if that key does not exist. If the key isn't convertible to the expected type, the end of the container is returned.

### void Iterable::insertKey(const QVariant &key)

Inserts a new entry with the given key, or resets the mapped value of any existing entry with the given key to the default constructed mapped value. The key is coerced to the expected type: If it isn't convertible, a default value is inserted.

### QMetaAssociation::Iterable::Iterator Iterable::mutableFind(const QVariant &key)

Retrieves an iterator pointing to the element at the given key, or the end of the container if that key does not exist. If the key isn't convertible to the expected type, the end of the container is returned.

### void Iterable::removeKey(const QVariant &key)

Removes the entry with the given key from the container. The key is coerced to the expected type: If it isn't convertible, the default value is removed.

### void Iterable::setValue(const QVariant &key, const QVariant &mapped)

Sets the mapped value associated with key to mapped, if possible. Inserts a new entry if none exists yet, for the given key. If the key is not convertible to the key type, the value for the default-constructed key type is overwritten.

See also value().

### QVariant Iterable::value(const QVariant &key) const

Retrieves the mapped value at the given key, or a QVariant of a default-constructed instance of the mapped type, if the key does not exist. If the key is not convertible to the key type, the mapped value associated with the default-constructed key is returned.

See also setValue().