This screen
shot shows the CFO object as a key within the variables
structure. You can see each function (or method) available
within the CFO object. You can also see the property, “DSN"
with its value, “companyInfo" in the right column.
Building a CFC with the cfscript
function
Let’s go one step further and add a new method
to the CFC. Because I’m a cfscript
fan, I won’t use the cffunction
tags. This time, I’ll build the CFC method with the
cfscript function.
At the bottom of your CFC file, (just above </CFCOMPONENT>)
add the following script:
<CFSCRIPT>
function authenticateUser(username, password) {
var SQLString = "SELECT UserID FROM LoginInfo
WHERE UserID='#arguments.username#'
AND Password = '#arguments.password#'";
/* perform the Query, remember, the DSN is already set! */
var checkUser=this.QUERY(SQLString);
/* Trace the SQL Statement to the Browser */
this.OUTPUT("Trace: " & SQLString, true);
/* Return a value of true or false to the user */
if (checkUser.recordCount neq 0) return true;
else return false;
}
</CFSCRIPT>
This cfscript
function will call some of the functions you declared within
the CFC. (Note, that’s where the “this"
comes in). The “this" is not required, but it’s
always preferable to scope variables so that ColdFusion
doesn’t search all the server to find it.
Now I’ll step through the function
line by line. First, the function, authenticateUser, was
defined with two arguments, “username" and “password".
Next, a SQL string was developed to select the UserID from
the LoginInfo table, where the supplied username and password
arguments are passed.
The value of SQLString is then sent
to the “QUERY" function, defined earlier within
the CFC. The data returned will be stored in a local function
variable called "checkUser." The data source is
not required, because it is set as a property of the ColdFusion
(CFO) object. Following the query, a simple cfoutput
tag lets you see what was sent to the query.
Finally, a recordCount challenge for the query, named checkUser
checks for a value of zero. If it isn’t zero, it means
a match was found, and a Boolean value of “true"
is sent back to the caller.
Tip: You should be aware that the SQL
mentioned in the above code has the potential of an injection
hack (someone putting some malicious code within the login
and password fields). To compensate for that, you can (optionally)
escape the single quotes using a replace command:
var SQLString = "Select UserID From LoginInfo where
UserID='#replace(arguments.username,"'","''","ALL")#' and
Password = '#replace(arguments.password,"'","''","ALL")#'";
Accessing the authenticateUser() function
Now the authentication function can now be accessed
from any ColdFusion page by simply calling the authenticate
method, passing the username and password.
<CFSCRIPT>
IF (CFO.authenticateUser("BobZ", "Ads10")) {
/* User Authenticated*/
CFO.Output("Success!");
}
ELSE {
/* User Login Failed */
CFO.Output("Failed!");
}
</CFSCRIPT>
In most cases, you wouldn’t hardcode the username
and password. I only hardcoded the values for demonstration
purposes. Typically, you’d use parameters sent from
a form post method, as follows:
CFO.authenticateUser(FORM.username, FORM.password)
Clearly you can do a lot with this concept. I hope I've
helped you see what you can achieve with this approach.
Certainly, there are other ways to achieve what I've set
out to do in this column. This article was intended to start
you thinking about objects, methods and properties. Object-oriented
ColdFusion development is powerful. If you want to excel
in ActionScript with Macromedia Flash MX or the Macromedia
Flash Communication Server, I strongly recommend you read
more about them in the application developer centers and
in books.
You can find a lot of functions on the Common
Function Library Project. This open-source repository
of ColdFusion functions is managed by Ray Camden and Rob
Brook-Bilson. Check it out, there are already a number of
ColdFusion Tag Libraries converted to cfscript
functions.
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