Adobe 38043740 Developing Applications - Page 886

DEVELOPING COLDFUSION 9 APPLICATIONS 881 Requesting and Presenting Information Importing tag-specific JavaScript files In the following situations, ColdFusion does not automatically import the JavaScript files that are required for Ajaxbased tags: • If you use a ColdFusion Ajax-based tag on a page that you specify by using a source or bind attribute in a container tag, such as cfdiv, cflayoutarea, cfpod, or cfwindow. Place a cfajaximport tag on the page that has the container tag and use the tags attribute to specify the Ajax feature tags that are on the other pages. (You do not have to do this for any tags that are also used on the page with the source attribute.) • If you use a ColdFusion Ajax JavaScript function, such as ColdFusion.Window.create or ColdFusion.navigate, on a page that does not otherwise import the required ColdFusion Ajax JavaScript functions, use the cfajaximport tag to import the required JavaScript functions. If you are using a function, such as coldFuson.navigate, that is not used for a specific control, you can omit any attributes; the default behavior is to import the base functions that are not control-specific. If you are using a function such as ColdFusion.Window.create, use the tags attribute and identify the associated control, for example, cfwindow in the following line: For detailed information on importing tag-specific JavaScript files, see the cfajaximport tag in the CFML Reference. Using data interchange formats All complex data that is communicated over an HTTP connection must be serialized into a string representation that can be transmitted over the web. Most commonly, web client applications use XML or JSON. As a general rule, ColdFusion automatically handles all necessary serialization and deserialization when you use ColdFusion Ajax features. The proxies that you create with the cfajaxproxy tag, and the bind expressions that call CFC functions automatically request data in JSON format, and automatically deserialize JSON data to JavaScript variables. ColdFusion also provides the capability to create, convert, and manage data in web interchange formats. This is helpful, for example, if you use custom Ajax elements to get data from ColdFusion servers. Also, you use ColdFusion data serialization capability for any applications that create or consume complex data transmitted over an HTTP connection. For example, if you want to make a web service or feed available in JSON format, many Yahoo! web services currently are accessible by using simple URLS that return data as JSON. Note: For information on ColdFusion tags and functions for handling XML or WDDX data, see "Using XML and WDDX" on page 1058. Controlling CFC remote return value data format By default, CFC functions convert data that they return to remote callers to WDDX format. However, they can also return the data in JSON format, or as plain string data. (XML objects are automatically converted to string representation when returning plain data.) ColdFusion Ajax elements that request data from CFC functions, including bind expressions and the function proxies generated by the cfajaxproxy tag, automatically generate a returnFormat parameter in the HTTP URL to request JSON data from the CFC function. Control the CFC function return format in the following ways: • Use the returnFormat attribute on the cffunction tag. • Set a returnFormat parameter in the HTTP request that calls the CFC function. • Use the CFC proxy setReturnFormat function. (You do this only if your client-side code requires non-JSON format data, for example, XML or WDDX.) Last updated 1/20/2012