QQmlPropertyMap

The QQmlPropertyMap class allows you to set key-value pairs that can be used in QML bindings. More…

Synopsis

Functions

• def clear (key)

• def contains (key)

• def count ()

• def freeze ()

• def insert (key, value)

• def insert (values)

• def isEmpty ()

• def keys ()

• def operator[] (key)

• def size ()

• def value (key)

Virtual functions

• def updateValue (key, input)

Signals

• def valueChanged (key, value)

Detailed Description

QQmlPropertyMap provides a convenient way to expose domain data to the UI layer. The following example shows how you might declare data in C++ and then access it in QML.

In the C++ file:

// create our data
QQmlPropertyMap ownerData;
ownerData.insert("name", QVariant(QString("John Smith")));
ownerData.insert("phone", QVariant(QString("555-5555")));

// expose it to the UI layer
QQuickView view;
QQmlContext *ctxt = view.rootContext();
ctxt->setContextProperty("owner", &ownerData);

view.setSource(QUrl::fromLocalFile("main.qml"));
view.show();

Then, in main.qml:

Text { text: owner.name + " " + owner.phone }

The binding is dynamic - whenever a key’s value is updated, anything bound to that key will be updated as well.

To detect value changes made in the UI layer you can connect to the valueChanged() signal. However, note that valueChanged() is NOT emitted when changes are made by calling insert() or clear() - it is only emitted when a value is updated from QML.

Note

It is not possible to remove keys from the map; once a key has been added, you can only modify or clear its associated value.

Note

When deriving a class from QQmlPropertyMap , use the protected two-argument constructor which ensures that the class is correctly registered with the Qt Meta-Object System .

Note

The QMetaObject of a QQmlPropertyMap is dynamically generated and modified. Operations on that meta object are not thread safe, so applications need to take care to explicitly synchronize access to the meta object.

class PySide6.QtQml.QQmlPropertyMap([parent=None])

Parameters

parent – PySide6.QtCore.QObject

Constructs a bindable map with parent object parent.

PySide6.QtQml.QQmlPropertyMap.clear(key)

Parameters

key – str

Clears the value (if any) associated with key.

PySide6.QtQml.QQmlPropertyMap.contains(key)

Parameters

key – str

Return type

bool

Returns true if the map contains key.

See also

size()

PySide6.QtQml.QQmlPropertyMap.count()

Return type

int

This is an overloaded function.

Same as size() .

PySide6.QtQml.QQmlPropertyMap.freeze()

Disallows any further properties to be added to this property map. Existing properties can be modified or cleared.

In turn, an internal cache is turned on for the existing properties, which may result in faster access from QML.

PySide6.QtQml.QQmlPropertyMap.insert(values)

Parameters

values –

Inserts the values into the QQmlPropertyMap .

Keys that don’t exist are automatically created.

This method is substantially faster than calling insert(key, value) many times in a row.

PySide6.QtQml.QQmlPropertyMap.insert(key, value)

Parameters

• key – str

• value – object

Sets the value associated with key to value.

If the key doesn’t exist, it is automatically created.

PySide6.QtQml.QQmlPropertyMap.isEmpty()

Return type

bool

Returns true if the map contains no keys; otherwise returns false.

See also

size()

PySide6.QtQml.QQmlPropertyMap.keys()

Return type

list of strings

Returns the list of keys.

Keys that have been cleared will still appear in this list, even though their associated values are invalid QVariants.

PySide6.QtQml.QQmlPropertyMap.operator[](key)

Parameters

key – str

Return type

object

This is an overloaded function.

Same as value() .

PySide6.QtQml.QQmlPropertyMap.size()

Return type

int

Returns the number of keys in the map.

See also

isEmpty() count()

PySide6.QtQml.QQmlPropertyMap.updateValue(key, input)

Parameters

• key – str

• input – object

Return type

object

Returns the new value to be stored for the key key. This function is provided to intercept updates to a property from QML, where the value provided from QML is input.

Override this function to manipulate the property value as it is updated. Note that this function is only invoked when the value is updated from QML.

PySide6.QtQml.QQmlPropertyMap.value(key)

Parameters

key – str

Return type

object

Returns the value associated with key.

If no value has been set for this key (or if the value has been cleared), an invalid QVariant is returned.

PySide6.QtQml.QQmlPropertyMap.valueChanged(key, value)

Parameters

• key – str

• value – object