Building ColdFusion components
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Example: sharing the Variables scope
The following example shows how a CFC can change data in the calling page’s Variables scope.
The callGreetMe.cfm page
<cfset Variables.MyName="Oswaldo">
<cfobject component="greetMe" name="myGreetings">
<cfoutput>
Before invoking the CFC Variables.Myname is #Variables.MyName#.<br>
Calling GreetMe CFC. It returns: #myGreetings.hello(VScope=Variables)#<br>
After invoking the CFC Variables.Myname is #Variables.MyName#.
</cfoutput>
The greetMe CFC
<cfcomponent>
<cffunction name="hello">
<cfargument name="Vscope" Required=true>
<cfset oldName=Arguments.VScope.MyName>
<cfset Arguments.VScope.MyName="Sandra">
<cfreturn "Hello " & oldName>
</cffunction>
</cfcomponent>
In this example, the callGreetMe.cfm does the following:
1
Sets the MyName variable in its Variables scope to “Oswaldo”
2
Displays the Variables.MyName value.
3
Calls the greetMe CFC and passes its Variables scope as a parameter.
4
Displays the value returned by the greetMe CFC.
5
Displays the Variables.MyName value.
The greetme.cfc component does the following:
1
Gets the calling page’s Variables scope as the Vscope parameter.
2
Changes the value of the MyName variable in Arguments.Vscope to “Sandra”
3
Returns a string consisting of the original name from the Arguments.Vscope variable.
When you run the CFC, displays the following output, showing that the CFC changed the
MyName variable the calling page’s Variables scope:
Before invoking the CFC Variables.Myname is Oswaldo.
Calling GreetMe CFC. It returns: Hello Oswaldo
After invoking the CFC Variables.Myname is Sandra.
The Arguments scope
The Arguments scope exists only in a method, and is not available outside the method. It contains
the variables passed into the method, including variables passed in the following ways:
•
As named attributes to the
cfinvoke
tag
•
In the
cfargumentcollection
attribute of the
cfinvoke
tag
•
In
cfinvokeargument
tags
•
As attributes or parameters passed into the method when the method is invoked as a web
service, by Flash Remoting, as a direct URL, or by submitting a form.
Содержание ColdFusion MX
Страница 1: ...Developing ColdFusion MX Applications...
Страница 22: ...22 Contents...
Страница 38: ......
Страница 52: ...52 Chapter 2 Elements of CFML...
Страница 162: ......
Страница 218: ...218 Chapter 10 Writing and Calling User Defined Functions...
Страница 250: ...250 Chapter 11 Building and Using ColdFusion Components...
Страница 264: ...264 Chapter 12 Building Custom CFXAPI Tags...
Страница 266: ......
Страница 314: ...314 Chapter 14 Handling Errors...
Страница 344: ...344 Chapter 15 Using Persistent Data and Locking...
Страница 349: ...About user security 349...
Страница 357: ...Security scenarios 357...
Страница 370: ...370 Chapter 16 Securing Applications...
Страница 388: ...388 Chapter 17 Developing Globalized Applications...
Страница 408: ...408 Chapter 18 Debugging and Troubleshooting Applications...
Страница 410: ......
Страница 426: ...426 Chapter 19 Introduction to Databases and SQL...
Страница 476: ...476 Chapter 22 Using Query of Queries...
Страница 534: ...534 Chapter 24 Building a Search Interface...
Страница 556: ...556 Chapter 25 Using Verity Search Expressions...
Страница 558: ......
Страница 582: ...582 Chapter 26 Retrieving and Formatting Data...
Страница 668: ......
Страница 734: ...734 Chapter 32 Using Web Services...
Страница 760: ...760 Chapter 33 Integrating J2EE and Java Elements in CFML Applications...
Страница 786: ...786 Chapter 34 Integrating COM and CORBA Objects in CFML Applications...
Страница 788: ......
Страница 806: ...806 Chapter 35 Sending and Receiving E Mail...