ColdFusion Tips & Tricks

prasannavigneshr · #21 02-18-2008, 09:09 PM

Forcing a user to relog after x number of minutes

If you wish for a user to be redirected to the login page after they have been inactive for x number of minutes instead of waiting for them to jump to another page, add the following line inside the <head></head> block of your html:

<META HTTP-EQUIV="refresh" CONTENT="901;URL='login.cfm'">

This assumes that your session timeout is set for 15 minutes (900 seconds).

prasannavigneshr · #22 02-18-2008, 09:10 PM

Forcing the browser not to cache a document

If you have a page that seems to be caching via the browser and can't explain why, try adding the following lines of code inside the <head></head> block of your HTML:

Code:

<META HTTP-EQUIV="expires" CONTENT="Fri, 1 Jan 1990 00:00:00 GMT">
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">
<META HTTP-EQUIV="cache-control" VALUE="no-cache, no-store, must-revalidate">

I've encounted this when I use a form to call another Cold Fusion program that performs file/database updates and then uses CFLOCATION to redirect back to the calling program.

This will solve the cache problem in Netscape, however, Internet Explorer is a different story. If you are using IE 3.xx, the only way to get out of the caching problem is to either upgrade to IE4 or to get rid of the frames. See KB article Q176797 for more information. If you are using IE4, you actually have to add a 2nd <head></head> block at the end of your html code, after the </body> tag but before the </html> tag. In this case, you only need to duplicate the Pragma=no-cache tag.

Code:

 <HTML>
    <HEAD>

        <META HTTP-EQUIV="REFRESH" CONTENT="5">
        <TITLE> Pragma No-cache </TITLE>

    </HEAD>
    <BODY>

        This is an example of where to place the second header section<br>
        so that the "Pragama, No-Cache" metatag will work as it is supposed to.<br>

    </BODY>
    <HEAD>

        <META HTTP-EQUIV="PRAGMA" CONTENT="NO-CACHE">

    </HEAD>
    </HTML>

prasannavigneshr · #23 02-18-2008, 09:11 PM

Grabbing informaion from another website

If you want to grab a bit of information from another website, you can use the CFHTTP tag to pull in the HTML of the site in question and store it in a variable.

I did basically the same thing in creating a Comic's page that lists all of my favorite comics. It has to scan a few of the comic websites each day since they use a seemingly random number as part of the GIF file names that changes from day to day. Attached is an excerpt of my code that I use to search the html for the GIF file name.

Basically, you need to know of a string of text that will never change (you hope) in it's position to whatever information you want. Search for the location of this string of text and if you find it, search after it for the last of the text you want.

Feel free to steal it. : P Note that it's been a couple months since I used this program so maybe it'll still find the Dilbert strip, maybe it won't.

Example HTML/CFML code:

Code:

<!--- Main program --->

<CFSET title="Dilbert">
<CFSET base="http://www.dilbert.com">
<CFSET url="http://www.dilbert.com/comics/dilbert/">
<CFSET search="/comics/dilbert/archive/images/dilbert">
<CFINCLUDE TEMPLATE="ComicSearch.cfm">
<CFINCLUDE TEMPLATE="HTML.cfm">

<!--- ComicSearch.cfm --->
<CFSET ck=0>

<CFHTTP URL="#url#"
        METHOD="GET">
</CFHTTP>
<CFSET dat=CFHTTP.FileContent>

<CFSET loc1=Find(search,dat)>
<CFIF loc1 EQUAL 0>
  <CFSET ck=1>
<CFELSE>
  <CFSET loc2=Find(Chr(34),dat,loc1)>
  <CFSET strip="#base##Mid(dat,loc1,loc2 - loc1)#">
</CFIF>

<!--- HTML.cfm --->
<CFOUTPUT>
<table border="0" width="90%"><tr><td BGCOLOR="##FFFF00">
<font face="Arial" size="5">&nbsp;&nbsp;#title#</font>
</td></tr></table>
</CFOUTPUT>

<CFIF ck EQUAL 0>
  <CFOUTPUT>
  <a href="#url#"><img src="#strip#" border="0"></a><br><br>
  </CFOUTPUT>
<CFELSE>
  <CFOUTPUT>Unable to determine the image filename<br><br></CFOUTPUT>
  <CFSET ck=0>
</CFIF>

prasannavigneshr · #24 02-18-2008, 09:12 PM

IE: Changing the contents of your website on the fly with <DIV>

Say you want to change what is displayed on your page based on a user action or you want to change something on the fly for a long-executing process. An example would be the Microsoft Windows Update website with Win2k/XP - it's displaying it's progress as it searches for updates.

With IE, you can use a combination of Javascript and the <DIV> tag to do so.

Note that changing the page contents while the task is still being executed requires the use of the <CFFLUSH> tag - which makes that tag unavailable for CF 4.x and below. Due note that you can still use Javascript functions to update the contents of <div> tags but that limits you to only what can be done after the page generation is complete and the rendered HTML sent to the user.

For an example, let's say that you want to display to the user the percentage complete of the current task - as it's still being executed.

First, we need to "prime the pump" by displaying a div tag that we'll alter later. Note that you must have some text inside the div tag or you will not be able to update it (a Javascript error is generated).

Code:

<CFOUTPUT>
<div id="Audit">The current task is 0% complete.</div>
</CFOUTPUT>

Now updating the contents of that div tag is a breeze.

Code:

<script language="Javascript">
Audit.innerHTML='The current task is #Per#% complete.';
</script>

One thing to keep in mind is that the Javascript block is only executed after it receives the </script> tag.

Here's a Copy-n-Paste demo version. Note that I pad the output buffer with a lot of extra "x" characters inside an HTML comment block on line 2. This is because the CFFLUSH tag will not flush anything unless it has at least 1k of data to send. After the initial flush, you can flush the buffer any time you wish.

Code:

<CFOUTPUT>
<!-- #RepeatString("x",1024)# -->
<font face="Arial" size="4">
<div id="Audit">The current task is 0% complete.</div>
</font>
</CFOUTPUT>
<CFFLUSH>

<CFLOOP index="Per" from="1" to="100">
  <CFOUTPUT>
  <script language="Javascript"> 
  Audit.innerHTML='The current task is #Per#% complete.';
  </script>
  </CFOUTPUT>
  <CFFLUSH>
  <!--- Insert a little delay --->
  <CFLOOP index="loop" from="1" to="10000">
  </CFLOOP>
</CFLOOP>

Another method you could use is to update the value of a <div> block using Javascript timeouts.

Okay, let's say you want to change the text of a block if the user moves the mouse over it and restore it when they move the mouse off.

Code:

<font face="Arial" size="4">
<div onMouseOver="this.innerHTML='Hey, get <b>OFF</b> of me!'"
     onMouseOut="this.innerHTML='I feel so lonely.'">I need a hug.</div>
</font>

The above example shows the use of two Javascript events in order to change the contents of a <div> block - and also shows that you need to stay away from embedding HTML in the middle of your text. If you try the above example, you'll notice that it'll execute the onMouseOut event if you move your mouse cursor to the left or right of "OFF" where the bold tags reside and it won't execute the onMouseOver event until you move your mouse off of the text and then back on.

An important note - when changing the contents of a <div> tag, you are using Javascript - so be sure to escape your special characters with the backslash. Example, you can't display a backslash by just sending a backslash - you have to send TWO backslashes - the first one escapes the 2nd.

Quote:

Bad: Audit.innerHTML='Path C:\Windows\System32';
Good: Audit.innerHTML='Path C:\\Windows\\System32';

prasannavigneshr · #25 02-18-2008, 09:13 PM

Inserting a LONG field into Oracle

The LONG datatype is a weird one. If you attempt to insert a value that is less than 2000 characters it will return an error. However, if you attempt to insert a value that is greater than 2000 characters, you have to define it as a LONG type before putting it into the database. In the following example the Rules_HTML field is a LONG datatype but it may not be 2000 characters. Here is my CF code to deal with this information:

Example HTML/CFML code:

Code:

<!--- First set a variable to the length of the value of the Rules_HTML field --->
<CFSET RulesHTMLLength = Len(form.Rules_HTML)>

<CFQUERY NAME="UpdatePromo" DATASOURCE="#Application.Datasource#">
<!--- If the Rules_HTML length is gt 2000 characters define it as a LONG field --->
<CFIF RulesHTMLLength GT 2000>
  DECLARE Rules_HTML_Temp LONG;
  BEGIN
  Rules_HTML_Temp := '#Rules_HTML#';
</CFIF>

UPDATE PROMO
SET   Banner_Image_ID = #form.Banner_Image_ID#
  , Logo_Image_ID = #form.Logo_Image_ID#
  , Front_Page_Image_ID = #form.Front_Page_Image_ID#
  , Begin_Date = '#DateFormat(form.Begin_Date, "DD-MMM-YYYY")#'
  , End_Date = '#DateFormat(form.End_Date, "DD-MMM-YYYY")#'
  , Notes = '#form.Notes#'
  , Summary_HTML = '#form.Summary_HTML#'
  , Tag_Line = '#form.Tag_Line#'
<!--- If the Rules_HTML field is a long datatype, insert the variable pointing to the value --->
<CFIF RulesHTMLLength GT 2000>
  , Rules_HTML = Rules_HTML_Temp
<CFELSE>
<!--- If it's not a long datatype, do a normal insert, with the actual rules_html field itself --->
  , Rules_HTML = '#form.Rules_HTML#'
</CFIF>
WHERE Promo_ID = #form.Promo_ID#
<!--- Then if the rules_html field is a long field, you have to add a semicolon and an END statement --->
<CFIF RulesHTMLLength GT 2000>
;
END;
</CFIF>
</CFQUERY>

prasannavigneshr · #26 02-18-2008, 09:13 PM

Issues with comma separated documents and Excel

This is just a FYI in case you ever run into this problem.

If you are dynamically creating a delimited text file to use for importing into Excel, you might want to take note of this in order to prevent catching flack from the overzealous users of your projects.

First, forget about the CSV extension. Don't use it. The document may open up correctly if downloaded and opened from a URL but if the users save it to their desktop and then open it, Excel seems to ignore the cell delimiter and stuffs everything into column A.

Also, Netscape likes to consider CSV files as text and displays it in the browser instead of opening Excel.

In order to resolve the above issues and others, perform the following steps.

* Use the XLS file extension. Excel, upon opening the document, will realize it's a text file and will translate it.
* Use the TAB - Chr(9) - as the cell delimiter.
* Write the file to the server's hard drive.
* Use <CFCONTENT> to send the file to the user.

In your URL for downloading the document to the user, simply call your template again with a URL variable specifying the file to send the user and the following code will send it to the user without altering whatever information is currently being displayed on the web site. Assuming your template name is "GenerateReport.cfm", your HTML would read: <a href="GenerateReport.cfm?SendFile=#filename#">

The two Find functions ensure the user isn't trying to get the program to download something they are not supposed to be downloading.

Example HTML/CFML code:


<CFPARAM name="URL.SendFile" DEFAULT="">
<CFIF URL.SendFile NEQ "" AND Find("/",URL.SendFile) EQ 0 AND Find("\",URL.SendFile) EQ 0>
<cfcontent type="application/vnd.ms-excel" file="#GenFilePath##URL.SendFile#" deletefile="No">
<CFABORT>
</CFIF>

prasannavigneshr · #27 02-18-2008, 09:15 PM

javascript: Checking for illegal characters

These functions checks for illegal characters in a form field. The ValidString( ) function does all the work but the others listed below are generic shortcuts for typical functions. They return true or false, you'll have to code in your own alert message in your validation function if these return false.

Example HTML/CFML code:

Code:

<script language="Javascript">

// Returns true if the string only contains alpha characters (empty string = true)
function isAlpha(txt)
{
	return ValidString(txt,'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz');
}

// Returns true if the string only contains numeric characters (empty string = true)
function isNumeric(txt)
{
	return ValidString(txt,'0123456789');
}

// Returns true if the string only contains alpha numeric characters (empty string = true)
function isAlphaNumeric(txt)
{
	return ValidString(txt,'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789');
}

// Returns true if the CheckString only contains characters passed in ValidString (empty string = true)
function ValidString(ChkString,ValidString)
{
	for (i=0; i<ChkString.length; i++)
	{
		if (ValidString.indexOf(ChkString.substring(i,i+1)) == -1) return false;
	}
	return true;
}


function SubmitForm()
{
	if (!isAlpha(document.Test.Alpha.value)) { alert('Alpha Only must only contain A-Z or a-z');return }
	if (!isAlphaNumeric(document.Test.AlphaNumeric.value)) { alert('Alpha Numeric must only contain A-Z, a-z, or 0-9'); return }
	if (!isNumeric(document.Test.Numeric.value)) { alert('Number must only contain 0-9'); return }
	alert('All is okay!');
}
</script>

<form name="Test">
Alpha Only: <input type="Text" name="Alpha" value=""><br>
Alpha Numeric Only: <input type="Text" name="AlphaNumeric" value=""><br>
Numeric Only: <input type="Text" name="Numeric" value=""><br>
<input type="Button" value="Go!" onClick="SubmitForm()">
</form>

prasannavigneshr · #28 02-21-2008, 12:22 AM

javascript: Checking if required fields have data

Instead of creating multiple Javascript if conditions for every required form field that you have, you can call one function and it will check all of the fields you specified and display an error message if any do not have values.

The function uses a trim( ) function to strip out leading and trailing spaces.

Example HTML/CFML code:

Code:

<script language="Javascript">
function trim(thisString){
	var newString = thisString;
	while (newString.charCodeAt(0) < 33)
	{
		newString = newString.substring(1,newString.length);
	}
	
	while (newString.charCodeAt(newString.length - 1) < 33)
	{
		newString = newString.substring(0, newString.length - 1);
	}
	return newString;
}

// Validate that a list of fields contain a value (leading and traling spaces are removed)
// First paramter: the form reference.  If your form name is "ServiceForm", then pass "document.ServiceForm"
// Second Parameter: A pipe delimited list of field names (case senastive)
// Third Parameter: A pipe delimited list of field descriptions
//
function ValidateRequiredFields(thisform,Fields,Desc)
{
	var tmpVal='';
	var FieldArray=new Array();
	var DescArray=new Array();
	var tmp=0;
	// Create array for Field list
	tmpVal=Fields;
	do
	{
		tmp=tmpVal.indexOf('|');
		if (tmp == -1)
		{
			if (tmpVal != '')
			{
				FieldArray[FieldArray.length]=tmpVal;
				tmpVal='';
			}
		} else {
			FieldArray[FieldArray.length]=tmpVal.substring(0,tmp);
			tmpVal=tmpVal.substring(tmp + 1);
		}
	}
	while (tmpVal != '');
	// Create array for Desc list
	tmpVal=Desc;
	do
	{
		tmp=tmpVal.indexOf('|');
		if (tmp == -1)
		{
			if (tmpVal != '')
			{
				DescArray[DescArray.length]=tmpVal;
				tmpVal='';
			}
		} else {
			DescArray[DescArray.length]=tmpVal.substring(0,tmp);
			tmpVal=tmpVal.substring(tmp + 1);
		}
	}
	while (tmpVal != '');
	// Check to see if passed strings are of equal length
	if (FieldArray.length != DescArray.length)
	{
		alert('Fatal error: ValidateRequiredFields - Passed lists do not have the same length');
		return false;
	}
	// Validate fields
	for (i=0; i < DescArray.length; i++)
	{
		eval('tmpVal=thisform.' + FieldArray[i] + '.value');
		if (trim(tmpVal) == '')
		{
			alert(DescArray[i] + ' is required.');
			eval('thisform.' + FieldArray[i] + '.focus()');
			return false;
		}
	}
	return true;
}

function SubmitForm()
{
	if (!ValidateRequiredFields(document.Test,'FirstName|LastName','First Name|Last Name')) return false;
	alert('All is okay!');
}
</script>

<form name="Test">
First Name: <input type="Text" name="FirstName" value=""><br>
Last Name: <input type="Text" name="LastName" value=""><br>
<input type="Button" value="Go!" onClick="SubmitForm()">
</form>

prasannavigneshr · #29 02-21-2008, 12:23 AM

javascript: Checking to see if dropdown selection boxes have a selection

This function comes in handy if you have multiple required selection boxes and you want to easily check to see if the user has selected a value.

Example HTML/CFML code:

Code:

<script language="Javascript">

// Pass in a list of drop down fields that must have an item selected other than the first one (selectedIndex > 0)
// Example: if (!ValidateDropDown(document.ServiceForm,'ChannelCodeDesc|UserLevel','Channel Code|User Level')) return false;
function ValidateDropDown(thisform,Fields,Desc)
{
	var tmpVal='';
	var FieldArray=new Array();
	var DescArray=new Array();
	var tmp=0;
	var idx=0;
	// Create array for Field list
	tmpVal=Fields;
	do
	{
		tmp=tmpVal.indexOf('|');
		if (tmp == -1)
		{
			if (tmpVal != '')
			{
				FieldArray[FieldArray.length]=tmpVal;
				tmpVal='';
			}
		} else {
			FieldArray[FieldArray.length]=tmpVal.substring(0,tmp);
			tmpVal=tmpVal.substring(tmp + 1);
		}
	}
	while (tmpVal != '');
	// Create array for Desc list
	tmpVal=Desc;
	do
	{
		tmp=tmpVal.indexOf('|');
		if (tmp == -1)
		{
			if (tmpVal != '')
			{
				DescArray[DescArray.length]=tmpVal;
				tmpVal='';
			}
		} else {
			DescArray[DescArray.length]=tmpVal.substring(0,tmp);
			tmpVal=tmpVal.substring(tmp + 1);
		}
	}
	while (tmpVal != '');
	// Check to see if passed strings are of equal length
	if (FieldArray.length != DescArray.length)
	{
		alert('Fatal error: ValidateDropDown - Passed lists do not have the same length');
		return false;
	}
	// Validate fields
	for (i=0; i<FieldArray.length;i++)
	{
		eval('idx=thisform.' + FieldArray[i] + '.selectedIndex');
		if (idx == 0)
		{
			alert('Please select an item for ' + DescArray[i] + '.');
			return false;
		}
	}
	return true;
}

function SubmitForm()
{
	if (!ValidateDropDown(document.Test,'Gender|Age','Gender|Age Range')) return false;

	alert('All is okay!');
}
</script>

<form name="Test">
Gender:
<select name="Gender" size="1">
	<option value="">&lt; Select &gt;</option>
	<option value="M">Male</option>
	<option value="F">Female</option>
</select>
<br>
Age Range:
<select name="Age" size="1">
	<option value="">&lt;  Select &gt;</option>
	<option value="1">1-10</option>
	<option value="2">11-20</option>
	<option value="2">21-30</option>
	<option value="2">31-99</option>
</select>
<br><br>
<input type="Button" value="Go!" onClick="SubmitForm()">
</form>

prasannavigneshr · #30 02-21-2008, 12:25 AM

javascript: Checking to see if multi-dropdown selection boxes have a selection

This function comes in handy if you have multiple required multi-selection boxes and you want to easily check to see if the user has selected a value.

Example HTML/CFML code:

Code:

<script language="Javascript">

// Pass in a list of drop down fields that must have an item selected (will return false if none are)
// Example: if (!ValidateMultipleDropDown(document.ServiceForm,'ChannelCodeDesc|UserLevel','Channel Code|User Level')) return false;
function ValidateMultipleDropDown(thisform,Fields,Desc)
{
	var tmpVal='';
	var FieldArray=new Array();
	var DescArray=new Array();
	var tmp=0;
	var idx=0;
	// Create array for Field list
	tmpVal=Fields;
	do
	{
		tmp=tmpVal.indexOf('|');
		if (tmp == -1)
		{
			if (tmpVal != '')
			{
				FieldArray[FieldArray.length]=tmpVal;
				tmpVal='';
			}
		} else {
			FieldArray[FieldArray.length]=tmpVal.substring(0,tmp);
			tmpVal=tmpVal.substring(tmp + 1);
		}
	}
	while (tmpVal != '');
	// Create array for Desc list
	tmpVal=Desc;
	do
	{
		tmp=tmpVal.indexOf('|');
		if (tmp == -1)
		{
			if (tmpVal != '')
			{
				DescArray[DescArray.length]=tmpVal;
				tmpVal='';
			}
		} else {
			DescArray[DescArray.length]=tmpVal.substring(0,tmp);
			tmpVal=tmpVal.substring(tmp + 1);
		}
	}
	while (tmpVal != '');
	// Check to see if passed strings are of equal length
	if (FieldArray.length != DescArray.length)
	{
		alert('Fatal error: ValidateMultipleDropDown - Passed lists do not have the same length');
		return false;
	}
	// Validate fields
	for (i=0; i<FieldArray.length;i++)
	{
		tmp=0;
		eval('L=thisform.' + FieldArray[i] + '.length');
		for (x=0; x<L; x++)
		{
			eval('idx=thisform.' + FieldArray[i] + '.options[' + x + '].selected');
			if (idx == true) tmp++;
		}
		if (tmp == 0)
		{
			alert('Please select an item for ' + DescArray[i] + '.');
			return false;
		}
	}
	return true;
}

function SubmitForm()
{
	if (!ValidateMultipleDropDown(document.Test,'CellFeatures','Cell Features')) return false;

	alert('All is okay!');
}
</script>

<form name="Test">
Select the cell phone features you want:<br>
<select name="CellFeatures" size="7">
	<option>Automatic Pizza finder</option>
	<option>Belt clip with built-in yellow sticky pad, PostIt</option>
	<option>Headset with an super long cord</option>
	<option>Mother-in-law mute button</option>
	<option>Mother-in-law call blocking</option>
	<option>Three dozen face plates for every mood</option>
	<option>Wireless Web</option>
</select>
<br><br>
<input type="Button" value="Go!" onClick="SubmitForm()">
</form>

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