| CFML Reference |
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ColdFusion Tags |
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| CFML Reference |
|
|
ColdFusion Tags |
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Flushes currently available data to the client.
Data output tags, Page processing tags
<cfflush interval = "integer number of bytes">
cfcache, cfheader, cfinclude, cfsetting, cfsilent
The first occurrence of this tag on a page sends back the HTML headers and any other available HTML. Subsequent cfflush tags on the page send only the output that was generated after the previous flush.
When you flush data, ensure that enough information is available, as some browsers might not respond if you flush only a small amount. Similarly, set the interval attribute for a few hundred bytes or more, but not thousands of bytes.
Use the interval attribute only when a large amount of output will be sent to the client, such as in a cfloop or a cfoutput of a large query. Using this form globally (such as in the Application.cfm file) might cause unexpected errors when CFML tags that modify HTML headers are executed.
Caution: Once you have used this tag on a page, any CFML function or tag on the page that modifies the HTML header causes an error. (These include: cfcontent, cfcookie, cfform, cfheader, cfhtmlhead, and cflocation.)
Using the cfset tag to set a cookie scope variable causes an error. Cookie errors can be caught with the cfcatch type = "Any" tag. Other errors can be caught with cfcatch type = "template".
Using the cfflush tag within a cfsavecontent tag (if the cfsavecontent tag has content) causes an error.
Note: Normally, the cferror tag discards the current output buffer and replaces it with the contents of the error page. The cfflush tag discards the current buffer. As a result, the Error.GeneratedContent variable resulting from a cferror tag after a cfflush contains any contents of the output buffer that has not been flushed. This content is not sent to the client. The content of the error page displays to the client after the bytes that have been sent.
The following example uses cfloop tags and the rand random number generating function to delay data display. It simulates a page that is slow to generate data.
<h1>Your Magic numbers</h1>
<p>It will take us a little while to calculate your ten magic numbers.
It takes a lot of work to find numbers that truly fit your
personality. So relax for a minute or so while we do the hard
work for you.</p>
<H2>We are sure you will agree it was worth the short wait!</H2>
<cfflush>
<cfflush interval=10>
<!--- Delay Loop to make it seem harder --->
<cfloop index="randomindex" from="1" to="200000" step="1">
<cfset random=rand()>
</cfloop>
<!--- Now slowly output 10 random numbers --->
<cfloop index="Myindex" from="1" to="10" step="1">
<cfloop index="randomindex" from="1" to="100000" step="1">
<cfset random=rand()>
</cfloop>
<cfoutput>
Magic number number #Myindex# is: #RandRange(
100000, 999999)#<br><br>
</cfoutput>
</cfloop>