QML Repeater Element

The Repeater element allows you to repeat an Item-based component using a model. More...

Inherits Item

Properties

• count : int
• delegate : Component
• model : any

Detailed Description

The Repeater element is used to create a large number of similar items. Like other view elements, a Repeater has a model and a delegate: for each entry in the model, the delegate is instantiated in a context seeded with data from the model. A Repeater item is usually enclosed in a positioner element such as Row or Column to visually position the multiple delegate items created by the Repeater.

The following Repeater creates three instances of a Rectangle item within a Row:

 import Qt 4.7

 Row {
     Repeater {
         model: 3
         Rectangle {
             width: 100; height: 40
             border.width: 1
             color: "yellow"
         }
     }
 }

The model of a Repeater can be any of the supported Data Models.

Items instantiated by the Repeater are inserted, in order, as children of the Repeater's parent. The insertion starts immediately after the repeater's position in its parent stacking list. This allows a Repeater to be used inside a layout. For example, the following Repeater's items are stacked between a red rectangle and a blue rectangle:

 Row {
     Rectangle { width: 10; height: 20; color: "red" }
     Repeater {
         model: 10
         Rectangle { width: 20; height: 20; radius: 10; color: "green" }
     }
     Rectangle { width: 10; height: 20; color: "blue" }
 }

The index and modelData properties

The index of a delegate is exposed as an accessible index property in the delegate. Properties of the model are also available depending upon the type of Data Model.

Here is a Repeater that uses the index property inside the instantiated items:

 Column {
     Repeater {
         model: 10
         Text { text: "I'm item " + index }
     }
 }

Here is another Repeater that uses the modelData property to reference the data for a particular index:

 Column {
     Repeater {
         model: ["apples", "oranges", "pears"]
         Text { text: "Data: " + modelData }
     }
 }

A Repeater item owns all items it instantiates. Removing or dynamically destroying an item created by a Repeater results in unpredictable behavior.

Considerations when using Repeater

The Repeater element creates all of its delegate items when the repeater is first created. This can be inefficient if there are a large number of delegate items and not all of the items are required to be visible at the same time. If this is the case, consider using other view elements like ListView (which only creates delegate items when they are scrolled into view) or use the Dynamic Object Creation methods to create items as they are required.

Also, note that Repeater is Item-based, and can only repeat Item-derived objects. For example, it cannot be used to repeat QObjects:

 Item {
     //XXX does not work! Can't repeat QObject as it doesn't derive from Item.
     Repeater {
         model: 10
         QObject {}
     }
 }

Property Documentation