Getting Started With ColdFusion Templates and Parameters - Passing Parameters Through the URL
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To create more interactive pages, sometimes you need to pass information (or parameters) from one ColdFusion template to another. There are basically 2 methods to do so:
- Pass through the URL
- Pass through a form
URL Parameters To pass a parameter to another ColdFusion template through a URL, you separate the URL from your parameter with a question mark (?). The question mark is followed by a "parameter name = value" pair. This is the standard syntax for passing parameters with any web browser and any web server, and its syntax looks like this:
<a href="template.cfm?parameter=value">Click here</a> If you want to pass more than one parameter, then you need to separate each with the ampersand (&):
<a href="template.cfm?parameter1=value1¶meter2=value2">Click here</a> Let's make a quiz that passes the user's answer through the URL. Enter the following into your editor and save the file as quiz.cfm in the learncf folder:
<html>
<body>
<h1>Today's Quiz</h1>
What am I learning now?
<ol>
<li><a href=quiz_answer.cfm?answer=ASP>ASP</a>
<li><a href=quiz_answer.cfm?answer=PHP>PHP</a>
<li><a href=quiz_answer.cfm?answer=ColdFusion>ColdFusion</a>
<li><a href=quiz_answer.cfm?answer=JSP>JSP</a>
</ol>
</body>
</html> You may notice that all the links are pointing to quiz_answer.cfm with the parameters appended to the end of the URL. The parameters differ from one link to another. Now, we need to create the quiz_answer.cfm file, which will handle the answer page. Enter the following code and save it as quiz_answer.cfm in the learncf folder:
<html>
<body>
<h1>Thank you!</h1>
What am I learning now?<br>
<cfoutput>
Your answer was <b>#url.answer#</b>
</cfoutput>
</body>
</html> Point your browser to http://localhost/learncf/quiz.cfm and click on an answer. You will see something like this:
What we have done is passed the value of a parameter from one page to another. You access the value by using #url.answer#, where answer is the parameters name. The url prefix you use here is the scope/type of the parameter.
How would you go about passing more than one parameter? As I said earlier, it's very easy. You simply separate them with an ampersand (&). The following code will pass the correct answer to the quiz_answer.cfm page by adding
&correct_answer=... to the links.
<html>
<body>
<h1>Today's Quiz</h1>
What am I learning now?
<ol>
<li><a href=quiz_answer.cfm?answer=ASP&correct_answer=ColdFusion>ASP</a>
<li><a href=quiz_answer.cfm?answer=PHP&correct_answer=ColdFusion>PHP</a>
<li><a href=quiz_answer.cfm?answer=ColdFusion&correct_answer=ColdFusion>ColdFusion</a>
<li><a href=quiz_answer.cfm?answer=JSP&correct_answer=ColdFusion>JSP</a>
</ol>
</body>
</html> The code below is a modified version of quiz_answer.cfm that handles the url.correct_answer parameter as well:
<html>
<body>
<h1>Thank you!</h1>
What am I learning now?<br>
<cfoutput>
<cfif url.answer eq url.correct_answer>
Congratulations, you answered correctly.
<cfelse>
Ops, you are wrong.
</cfif>
<br>
Your answer was <b>#url.answer#</b>
</cfoutput>
</body>
</html> The code shown above uses the <cfif> tag to check whether the user clicked on the correct answer. Depending on whether the answer is correct or not, the code will display a corresponding message. <cfif url.answer eq url.correct_answer> effectively evaluates whether url.answer was equal to url.correct_answer. eq is a comparison operator and represents is equal to in ColdFusion:
Next: Passing Parameters Through Forms >>
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