Qt 4.8: QML Connections Element

Qt Reference Documentation

- Qt 4.8
- ALL VERSIONS

- A
- A
- A
- Print

# QML Connections Element

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

This element was introduced in Qt 4.7.

- List of all members, including inherited members

## Properties

- ignoreUnknownSignals : bool
- target : Object

## 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.