-To deal conveniently with properties taking take big trunk of initial data, the following property initialization tag is introduced, +To facilitate initializing properties with big trunk of data, the following property initialization tag is introduced. It is equivalent to ...PropertyName="PropertyValue"... in every aspect. Property initialization tags must be directly enclosed between the corresponding opening and closing component tag. +
+Since version 3.1.0, the property initialization tag can also be used to initialize a set of subproperties who share the same parent property. For example, the following is equivalent to HeaderStyle.BackColor="black" and HeaderStyle.ForeColor="red".
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When specified in templates, component ID property has special meaning in addition to its normal property definition. A component tag specified with an ID value in template will register the corresponding component to the template owner control. The component can thus be directly accessed from the template control with its ID value. For example, in Home page's template, the following component tag
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Comment tags are used to put in a template developer comments that will not display to end-users. Contents enclosed within a comment tag will be treated as raw text strings and PRADO will not attempt to parse them. Comment tags cannot be used within property values. The format of comment tags is as follows,
Since version 3.0.5, PRADO starts to support external template inclusion. This is accomplished via include tags, where external template files are specified in namespace format and their file name must be terminated as .tpl.
-TRepeater displays its content defined in templates repeatedly based on the given data specified by the DataSource or DataSourceID property. The repeated contents can be retrieved from the Items property. Each item is created by instantiating a template and each is a child control of the repeater.
+TRepeater displays its content repeatedly based on the data fetched from DataSource. The repeated contents in TRepeater are called items which are controls accessible through Items property. When dataBind() is invoked, TRepeater creates an item for each row of data and binds the data row to the item. Optionally, a repeater can have a header, a footer and/or separators between items.
-Like normal control templates, the repeater templates can contain static text, controls and special tags, which after instantiation, become child contents of the corresponding item. TRepeater defines five templates for different purposes,
+The layout of the repeated contents are specified by inline templates. In particular, repeater items, header, footer, etc. are being instantiated with the corresponding templates when data is being bound to the repeater.
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+Since v3.1.0, the layout can also be specified by renderers. A renderer is a control class that can be instantiated as repeater items, header, etc. A renderer can thus be viewed as an external template (in fact, it can also be non-templated controls). A renderer can be any control class. If implemented with one of the following interfaces, a renderer will be initialized with additional properties relevant to the repeater items:
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+The following properties are used to specify different types of template and renderer for a repeater. If an item type is defined with both a template and a renderer, the latter takes precedence.
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To populate data into the repeater items, set DataSource to a valid data object, such as array, TList, TMap, or a database table, and then call dataBind() for the repeater. That is,
-Normally, you only need to do this when the page containing the repeater is initially requested. In postbacks, TRepeater is smart enough to remember the previous state, i.e., contents populated with datasource information.The following sample displays tabular data using TRepeater.
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+When dataBind() is called, TRepeater undergoes the following lifecycles for each row of data:
-TRepeater provides several events to facilitate manipulation of its items,
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+Normally, you only need to bind the data to repeater when the page containing the repeater is initially requested. When the page is post back, the repeater will restore automatically all its contents, including items, header, footer and separators. However, the data row associated with each item will not be recovered and thus become null.
+To access the repeater item data in postbacks, use one of the following ways:
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+TRepeater raises an OnItemCommand event whenever a button control within some repeater item raises a OnCommand event. Therefore,
+you can handle all sorts of OnCommand event in a central place by
+writing an event handler for OnItemCommand.
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The following example shows how to use TRepeater to display tabular data.
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TRepeater can be used in more complex situations. As an example, we show in the following how to use nested repeaters, i.e., repeater in repeater. This is commonly seen in presenting master-detail data. To use a repeater within another repeater, for an item for the outer repeater is created, we need to set the detail data source for the inner repeater. This can be achieved by responding to the OnItemDataBound event of the outer repeater. An OnItemDataBound event is raised each time an outer repeater item completes databinding. In the following example, we exploit another event of repeater called OnItemCreated, which is raised each time a repeater item (and its content) is newly created. We respond to this event by setting different background colors for repeater items to achieve alternating item background display. This saves us from writing an AlternatingItemTemplate for the repeaters.
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Besides displaying data, TRepeater can also be used to collect data from users. Validation controls can be placed in TRepeater templates to verify that user inputs are valid.
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The PRADO component composer demo is a good example of such usage. It uses a repeater to collect the component property and event definitions. Users can also delete or adjust the order of the properties and events, which is implemented by responding to the OnItemCommand event of repeater.
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See in the following yet another example showing how to use repeater to collect user inputs.
Template Control Tags
A template control tag is used to configure the initial property values of the control owning the template. Its format is as follows,
-TRepeater
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