計(jì)算機(jī)外文文獻(xiàn)譯文(編輯修改稿)
2025-01-08 17:32 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 d() is called. The following example illustrates binding to a property of another control. Binding to Collections and Lists List server controls like DataGrid, ListBox and HTMLSelect use a collection as a data source. The following examples illustrate binding to usual mon language runtime collection types. These controls can bind only to collections that support the IEnumerable, ICollection, or IListSource interface. Most monly, you39。ll bind to ArrayList, Hashtable, DataView and DataReader. The following example illustrates binding to an ArrayList. The following example illustrates binding to a DataView. Note that the DataView class is defined in the namespace. The following example illustrates binding to a Hashtable. Binding Expressions or Methods Often, you39。ll want to manipulate data before binding to your page or a control. The following example illustrates binding to an expression and the return value of a method. The framework supplies a static method that evaluates latebound data binding expressions and optionally formats the result as a string. is convenient in that it eliminates much of the explicit casting the developer must do to coerce values to the desired data type. It is particularly useful when data binding controls within a templated list, because often both the data row and the data field must be cast. Consider the following example, where an integer will be displayed as a currency string. With the standard data binding syntax, you must first cast the type of the data row in order to retrieve the data field, IntegerValue. Next, this is passed as an argument to the method. This syntax can be plex and difficult to remember. In contrast, is simply a method with three arguments: the naming container for the data item, the data field name, and a format string. In a templated list like DataList, DataGrid, or Repeater, the naming container is always . Page is another naming container that can be used with . The format string argument is optional. If it is omitted, returns a value of type object, as shown in the following example. It is important to note that can carry a noticeable performance penalty over the standard data binding syntax because it uses latebound reflection. Use judiciously, especially when string formatting is not required. Section Summary The declarative data binding syntax uses the % % notation. You can bind to data sources, properties of the page or another control, collections, expressions, and results returned from method calls. List controls can bind to collections that support the ICollection, IEnumerable, or IListSource interface, such as ArrayList, Hashtable, DataView
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