Assuming the following code in a regular .cfm file, not a CFC:
<cffunction name="myFunction">
<cfobject type="java" action="create" class="path.to.my.java.class" name="myJavaVariable">
</cffunction>
What is going to be the scope of the created object? I'm getting the feeling it's not limited to the function scope. If so, how to make it local? Would the following work?
<cfset var myJavaVariable = "">
<cfobject ... name="myJavaVariable">
EDIT:
I forgot to say I was under Coldfusion MX 7, as it does prevent some useful solutions found on the web from working.
I did find a workaround where one creates a fake local scope (<cfset var local = StructNew()>). It does work well even for such tags since you can put the return variable as local.someVar.
I'd question why you're using <cfobject> at all, rather than the more obvious simple assignment:
var myJavaVariable = createObject("java", "path.to.my.java.class");
Isn't that more natural code anyhow?
Related
I wrote the following function:
<cffunction name="check_session_valid" returntype="boolean">
<cfif NOT StructKeyExists(session,"username") OR (len(session.username) EQ 0)>
<script>location.href = 'logout.cfm'</script>
<cfabort>
</cfif>
<cfset session.myApp_start = now()>
<cfreturn true>
</cffunction>
In my .cfm page, I can call that function using
<cfset session_valid = application.lib.check_session_valid()>
OR
#application.lib.check_session_valid()#
What's the difference? Best practice?
Since you asked about best practice, which is a matter of opinion, I think you can improve your function by having it returning either true or false depending on whether or not session.username exists and has a length greater than 0. Then you can use it like this:
<cfif application.lib.check_session_valid()>
code for this condition
<cfelse>
<cflocation href = "logout.cfm">
<!--- note that cfabort is not necessary --->
<cfif>
Regarding your specific question, I think the extra variable, session_valid, is a waste of typing. However, that is simply my opinion.
Not related to your question, I found it curious that you would direct users to a page called logout.cfm. Often users are directed to a page that allows them to log in.
To be honest, both are valid and both would be considered best practice depending on what you are trying to do.
My rule of thumb is if I will need to use the result of a function call more than once, I will set it to a variable
myResult = application.lib.check_session_valid();
If I will only need to use the variable once I would do what Dan mentioned
if( application.lib.check_session_valid() ){
// Do stuff
}
The difference between the examples you showed are
<cfset session_valid = application.lib.check_session_valid()>
This will set the variable named session_valid to whatever is returned from the call to check_session_valid().
#application.lib.check_session_valid()#
This will, in .cfm pages, simply render the value returned from the call to check_session_valid() assuming it is inside of a <cfoutput> tag. There are other places this would also render the value, such as inside a <cfsavecontent>.
I am using ColdFusion 8.0.1.
I created a UDF library and put it in a CFC. I load the library in the APPLICTION scope like this:
// CREATE STRUCTURE OBJECTS
if (not isDefined("APPLICATION.AppOBJ") or not isStruct(APPLICATION.AppOBJ)) {
APPLICATION.AppOBJ = structNew();
APPLICATION.AppOBJ.udf_library = createObject("component", "udf.udf_library");
}
The library works great! But I want to reduce the code needed to access the functions, to shorten the reference. Currently, I have to access the functions like this:
APPLICATION.AppOBJ.udf_library.myFunction();
I want to be able to reference this library object as "UDF", like this:
UDF.myFunction();
In another ColdFusion 9 project (Again, this is a CF8 project!), I am able to do this right after I create the ojbect
<cfset udf = APPLICATION.AppOBJ.udf_library>
In the current project, this doesn't work in the application.cfm file. It DOES however, work when I put it on the page that it is being used.
My question is how far upstream can I put this last line of code to have the variable available on any page in the application? Is there a difference between CF8 and CF9 for this type of thing? Is the difference because I am working in application.CFM versus application.CFC?
Thanks!!!
-- EDIT -- MORE INFORMATION ---
The files that I am trying to access the APPLICATION.AppOBJ.udf_library object are within a custom tag. Might that matter?
-- ANSWER -- THANKS TO MICAH AND BEN NADEL ---
I haven't tried this yet but I think it should work as the idea comes from Ben Nadel's blog entry entitled Creating Globally Accessible User Defined Functions In ColdFusion (Safer Version)
<cfcomponent output="false" hint="I define the application settings and event handlers.">
<!--- Define the application. --->
<cfset this.name = "TestApp" >
<cfset this.applicationTimeout = createTimeSpan( 0, 0, 5, 0 ) >
<!---
Add all of our "global" methods to the URL scope. Since
ColdFusion will automatically seach the URL scope for
non-scoped variables, it will find our non-scoped method
names.
--->
<cfset structAppend( url, createObject( "component", "udf.udf_library" ) ) >
</cfcomponent>
You should now be able to access MyFunction() globally.
If you want to access the function as UDF.MyFunction() then I think you should be able modify Ben's example to the following:
<cfset UDF = StructNew() >
<cfset structAppend( UDF, createObject( "component", "udf.udf_library" ) ) >
<cfset structAppend( url, UDF ) >
I am using ColdFusion 8.0.1
I am working on an existing application that has thousands of pages. I am trying to include a library of new UDFs in my application.cfm file.
I addedd this line to application.cfm:
<!--- UDF library include --->
<cfinclude template="UDF/udf_library.cfm">
The UDF library includes other files that contain UDFs, like this:
<cfinclude template="udf_powerreview.cfm">
I have functions in the udf_powerreview.cfm file, such as:
// CREATE POWER REVIEWS SNIPPET
function createPRSnippet(Page_ID) {
LOCAL.Page_ID = ARGUMENTS.Page_ID;
if (isNumeric(LOCAL.Page_ID) && LOCAL.Page_ID > 0) {
LOCAL.Snippet = "<div class='pr_snippet_product'><script type='text/javascript'>var pr_snippet_min_reviews = 0; POWERREVIEWS.display.snippet(document, { pr_page_id : '#LOCAL.Page_ID#' });</script></div>";
} else {
LOCAL.Snippet = "";
}
return LOCAL.Snippet;
}
The debugging tool says that UDF/udf_library.cfm and udf_powerreview.cfm are being successfully included.
The problem is when I call the function in another page, I get an error that says that function doesn't exist. When I can copy the function and put it directly into the page that it is used in and it works just fine. And, I do not get the error "routines can not be declared twice".
In every site that I build, I create a udf_library.cfm or udf_library.cfc in the exact same manner. They always work fine.
What might prevent the functions from being available and accessed? Is there an application setting that needs to be set?
It's a page scope issue. Don't think of the Application.cfm as an include on all your pages, just know that it runs first. Somethings it initializes will carry over to your existing page scope and some things won't. Using an Application.cfc instead of an application.cfm takes care of much of the ambiguity.
To make your UDF's available to your whole application, I would suggest using a "Singleton" Design pattern. First take your UDF's and put them in a CFC format. This will make them more portable.
in your application.cfm you could put the following lines:
<cfif NOT isdefined('session.udf_powerreview') or isdefined('url.resetudf')>
<cfset session.udf_powerreview = createobject('Component','udf.udf_powerreview')/>
<!--- this 'udf.udf_powerreview' represents the physical path udf/udf_powerreview.cfc --->
</cfif>
I'm stuffing it in the session scope instead of the application scope, becuase you won't have an good way of resetting the application scope if you modify your UDF's.
Either way, once this is in your application.cfm you should be able to see your functions on any page.
<cfdump var="#session.udf_powerreview#">
Here is one strategy that I use. This basically calls the UDFs "on demand". It won't reimport the UDFs if it already exists. You do however have to have named arguments however, otherwise you'd have to strip out the UDFName out of the argument collection. I'm worried however that argument order might not be preserved, I haven't investigated that.
application.cfm
<cfapplication
name="udftest_001" />
<cffunction name="udf">
<cfargument name="udfname" type="string" required="true">
<cfif NOT isDefined(udfname)>
<cfinclude template='./udfs/#udfname#.cfm'>
</cfif>
<cfset tempfunc = variables[udfname]>
<cfreturn tempfunc(argumentCollection=arguments)>
</cffunction>
index.cfm
<cfoutput>
#udf(udfname='testUDF',firstname='John',lastname='Smith')#<br/>
#udf(udfname='testUDF',firstname='Betty',lastname='Ford')#<br/>
</cfoutput>
/udfs/testudf.cfm
<cfscript>
function testUDF() {
return 'Hello ' & arguments.firstname & ' #arguments.lastname#';
}
</cfscript>
I suspect something is up with relative paths.
Can you make "UDF" a mapping? Then you can do
<cfinclude template="/UDF/udf_library.cfm">
I am using the technique detailed in this answer to manage a library of small utility functions. (Essentially, each function is loaded as a "mix-in" using cfinclude.)
I have need, however, to know the names of the functions that the object has (once instantiated). A cfdump on the object only shows the init function which is written directly in the CFC.
Some more detail:
I am creating the object in the application scope in OnApplicationStart().
<cfset application.udfs=createObject("component","extensions.udfs").init()>
However, to save the developers from having to constantly write application.udfs.foo(), I thought I'd grab all of the functions and drop them in to the variables scope in OnRequestStart(), so that these hypothetical developers could just write foo().
<cfset foo=application.udfs.foo>
Obviously, though, this needs to be dynamic and to happen for each of the functions in the object, no matter how many there are. If I repeat this line for every function I've lost whatever I'd gained by having a library that is dynamically generated.
I thought perhaps I could use a collection loop, but that was invalid. I am fairly certain there's a way to get the list of methods in an object, but I have not yet been able to find it.
Any clues?
By the by, my fallback is going to be to copy the application.udfs object to a local object with a nice short name (like "u") so that the developers can simply type u.foo(), so no need to suggest that if what I want to do can't be done.
This should allow you to import all your udfs into the global variables scope:
StructAppend(variables, application.udfs);
I think GetMetaData should help you.
Here another interesting option suggested by Ben Nadel:
Check out the detail in his blog entry: http://www.bennadel.com/blog/1776-Creating-Globally-Accessible-User-Defined-Functions-In-ColdFusion-Safer-Version-.htm
UDF.cfc
<cfcomponent
output="false"
hint="I define user defined functions.">
<cffunction
name="getMessage"
access="public"
returntype="string"
output="false"
hint="I return a test message.">
<cfreturn "I am defined in the UDF component" />
</cffunction>
</cfcomponent>
Application.cfc
<!--- Define the application. --->
<cfset this.name = hash( getCurrentTemplatePath() ) />
<cfset this.applicationTimeout = createTimeSpan( 0, 0, 5, 0 ) />
<!---
Add all of our "global" methods to the URL scope. Since
ColdFusion will automatically seach the URL scope for
non-scoped variables, it will find our non-scoped method
names.
--->
<cfset structAppend(
url,
createObject( "component", "UDF" )
) />
By default, ColdFusion passes simple types (like numeric, string, and GUID) by value to functions. I'd like to pass a simple type by reference.
I'm currently wrapping a simple value in a struct (they get passed by reference). This solves my problem but it is very ugly:
<!--- TheFunctionName---->
<cffunction name="TheFunctionName">
<cfargument name="OutVariable" type="struct">
<cfset OutVariable.ID = 5>
</cffunction>
<cfset OutVariable=StructNew()>
<cfset TheFunctionName(OutVariable)>
<!--- I want this to output 5--->
<cfoutput>#OutVariable.ID#</cfoutput>
I'd rather something like this:
<!--- TheFunctionName---->
<cffunction name="TheFunctionName">
<cfargument name="OutVariable" passbyref="true">
<cfset OutVariable = 5>
</cffunction>
<cfset TheFunctionName(OutVariable)>
<!--- I want this to output 5--->
<cfoutput>#OutVariable#</cfoutput>
AFAIK, there's no way to pass simple values by reference in ColdFusion. The only workaround I can think of is the one you're already using.
Instead, I would suggest trying to restructure your program to work with the grain of the language. In cases where there's only one simple value to "modify", you could just make your function return the new value, and call it like:
<cfset SomeVar = TheFunctionName(SomeVar)>
In cases where you're modifying multiple values, take a step back and think about whether it's possible to bundle those multiple values up into a CFC with your mutator functions becoming methods of the CFC. This could be clearer and more maintainable solution anyway.
You can arrange for the variables used outside and inside the function to be in a scope that exists in both code areas. For example, if you put a variable in the "session" or the "request" scope you will be able to access it from within the function. The changes made will persist.
Note that when you are doing this you aren't actually "passing" the variables to the function. The function just assumes the variable exists or creates it, depending on how you code it.
<cffunction name="TheFunctionName">
<cfset Request.StrVar = "inside function<br />" />
</cffunction>
<cfscript>
Request.StrVar = "outside function<br />";
WriteOutput(Request.StrVar);
TheFunctionName();
WriteOutput(Request.StrVar);
</cfscript>
About ColdFusion Scopes
If there is any doubt about the calling page declaring the variable in advance when it is required you'll have to do some legwork with the <cfparam> tag or IsDefined() function.
If you:
declare the function inside of a CFC
invoke the function using <cfinvoke>
You would be able to specify the <cfinvoke> parameter "returnvariable", and then output that variable however you like.
<cfinvoke component="this" method="TheFunctionName" returnvariable="blah">
<cfinvokeargument name="data" value="whatever" type="string">
<cfreturn data>
</cfinvoke>
<cfdump var="#blah#">
If you are writing everything in cfscript, then I would go with what SurroundedByFish said.