MeeGo 1.2 Harmattan Developer Documentation Develop for the Nokia N9

QML Connections Element

A Connections element describes generalized connections to signals. More...

This element was introduced in Qt 4.7.


Detailed Description

A Connections object creates a connection to a QML signal.

When connecting to signals in QML, the usual way is to create an "on<Signal>" handler that reacts when a signal is received, like this:

 MouseArea {
     onClicked: { foo(parameters) }

However, it is not possible to connect to a signal in this way in some cases, such as when:

  • Multiple connections to the same signal are required
  • Creating connections outside the scope of the signal sender
  • Connecting to targets not defined in QML

When any of these are needed, the Connections element can be used instead.

For example, the above code can be changed to use a Connections object, like this:

 MouseArea {
     Connections {
         onClicked: foo(parameters)

More generally, the Connections object can be a child of some object other than the sender of the signal:

 MouseArea {
     id: area
 // ...
 Connections {
     target: area
     onClicked: foo(parameters)

See also QtDeclarative.

Property Documentation

ignoreUnknownSignals : bool

Normally, a connection to a non-existent signal produces runtime errors.

If this property is set to true, such errors are ignored. This is useful if you intend to connect to different types of objects, handling a different set of signals for each object.

target : Object

This property holds the object that sends the signal.

If this property is not set, the target defaults to the parent of the Connection.

If set to null, no connection is made and any signal handlers are ignored until the target is not null.