Stores a copy of a page on the server and/or client computer, to improve page rendering performance. To do this, the tag creates temporary files that contain the static HTML returned from a ColdFusion page.
Use this tag if it is not necessary to get dynamic content each time a user accesses a page.
You can use this tag for simple URLs and for URLs that contain URL parameters.
Page processing tags
<cfcache
action = "action"
dependsOn = "variable name list"
directory = "directory path"
expireURL = "wildcarded URL reference"
id = "object identifier"
idleTime = "decimal number of days"
metadata = "variable name"
name = "variable name"
password = "password"
port = "port number"
protocol = "http://|https://"
stripWhiteSpace = "false|true"
throwOnError = "false|true"
timespan = "decimal number of days">
useCache = "true|false"
username = "username"
value = "value">
The page fragment to be cached, if any.
</cfcache>
attributeCollection attribute
whose value is a structure. Specify the structure name in the attributeCollection attribute
and use the tag’s attribute names as structure keys.ColdFusion 9:
Added support for the following features:
Caching in memory. Memory is now the default cache location.
Caching page fragments.
Caching specific objects, including the ability to put, get, and flush cached objects.
Setting cache dependencies.
Setting an idle timeout.
Getting metadata about cached objects.
The ability to strip white space from cached page fragments.
The ability to throw an exception if an error occurs when flushing a cached object.
Added get and put values
of the action attribute. These values support caching
of objects.
Added dependsOn, id, idleTime, key, metadata, name, stripWhiteSpace, throwOnError, useCache,
and value attributes.
ColdFusion MX:
Deprecated the cachedirectory and timeout attributes.
They might not work, and might cause an error, in later releases.
Added the timespan attribute.
Changed how pages are cached: the default action attribute
value, cache, caches a page on the server and the
client. (In earlier releases, this option cached a page only on
the server.)
Changed the source of the protocol and port values:
the default protocol and port values
are now taken from the current page URL. (In earlier releases, they
were "http" and "80", respectively.)
Changed how session state is handled when caching a page: this tag can cache pages that depend on session state, including pages that are secured with a ColdFusion login. (In earlier releases, the session state was cleared when caching the page, causing authentication to be lost.)
Changed how files are cached: this tag uses a hash() of the URL for the filename to cache a file. (In earlier releases, ColdFusion used the cfcache.map file.)
Attribute |
Actions |
Req/Opt |
Default |
Description |
|---|---|---|---|---|
|
All |
Optional |
|
|
|
|
Optional |
A comma separated list of variables. If any of the variable values change, ColdFusion updates the cache. This attribute can take an expression that returns a list of variables. |
|
|
|
Optional |
Cache in memory |
Absolute path of cache directory. |
|
|
Optional |
Flush all cached pages |
A URL reference. Can include wildcards,
for example: |
|
|
See description |
The identifier for a cached object. This
attribute is required for the any operation on an object. Therefore it
is required for the |
|
|
|
Optional |
No idle timeout |
Flushes the cached item if it is not accessed for the specified time span:
|
|
|
Optional |
The name of a structure variable in which to put object metadata. The get operation returns the following data:
|
|
|
|
Required |
The name of the variable in which to put the retrieved object. |
|
|
|
Optional |
A password. Provide this if the page requires authentication at the web-server level. |
|
|
|
Optional |
The port for the current page |
Port number of the web server from which
the URL for the cached page is requested. In the internal call from |
|
|
Optional |
The current page protocol |
Protocol that is used to create URL from cache.
|
|
|
Optional |
|
Specifies whether to strip any unnecessary white space characters from a cached page fragment. Does not have any effect on cached pages or objects. |
|
|
Optional |
false |
A Boolean value specifying whether to throw
an error if the |
|
|
Optional |
See Description |
The interval until the item is flushed from the cache.
The default action is to flush
the item when it is idle for the time specified by the |
|
|
Optional |
|
Specifies whether to use caching for a page. This attribute can be useful during development., or you could use a function to predict when to use a cache based on the application state. |
|
|
Optional |
A username. Provide this if the page being cached or flushed requires authentication at the web server level. |
|
|
|
Required |
The object to cache. |
ColdFusion 9 additions
The following is new information applies to features added for ColdFusion 9. For additional information, see the History section and the Attributes table.
Page fragments: To cache a page fragment, put the fragment in the body of the tag, between the begin tag and the end tag. Do not use a tag body to cache full pages or objects.
flush: The flush action
can have two formats: One uses the ExpireURL attribute
to specify the page to flush, the other uses the id attribute
to specify the object to flush. When you flush an object, ColdFusion
ignores errors by default. If you specify a throwOnError attribute
with a true value, the action throws the errors,
and you can use a catch block to handle them. This is useful to determine
if you use invalid cache ID values.
From ColdFusion 8 and earlier
The following remaining information for this tag also applied to previous releases.
Use this tag in pages whose content is not updated frequently. Taking this action can greatly improve the performance of your application.
The
output of a cached page is stored in a file on the client browser
and/or the ColdFusion server. Instead of regenerating and downloading
the output of the page each time it is requested, ColdFusion uses
the cached output. ColdFusion regenerates and downloads the page
only when the cache is flushed, as specified by the timespan attribute,
or by invoking cfcache action=flush.
To enable
a simple form of caching, put a cfcache tag, specifying
the timespan attribute, at the top of a page. Each
time the specified time span passes, ColdFusion flushes (deletes)
the copy of the page from the cache and caches a new copy for users
to access.
You can specify client-side caching or a combination of client-side and server-side caching (the default), using the action attribute. The advantage of client-side caching is that it requires no ColdFusion resources; the browser stores pages in its own cache, improving performance. The advantage of combination caching is that it optimizes server performance; if the browser does not have a cache of the page, the server can get data from its own cache. (Adobe recommends that you use combination caching, and do not use server-side only caching.)
If a page contains personalized
content, use the action = "clientcache" option
to avoid the possibility of caching a personalized copy of a page
for other users.
Debug settings have no effect on cfcache unless
the application page enables debugging. When generating a cached
file, cfcache uses cfsetting showDebugOutput = "no".
The cfcache tag
evaluates each unique URL, including URL parameters, as a distinct
page, for caching purposes. For example, the output of http://server/view.cfm?id=1
and the output of http://server/view.cfm?id=2 are cached separately.
The cfcache tag
uses the cfhttp tag to get the contents of a page
to cache. If there is an HTTP error accessing the page, the contents
are not cached. If a ColdFusion error occurs, the error is cached.
For more information, see Caching ColdFusion pages that change infrequently in the Developing ColdFusion Applications.
<!--- This example produces as many cached files as there are URL parameter permutations.
You can see that the page is cached when the timestamp doesn't change.--->
<cfcache
timespan="#createTimeSpan(0,0,10,0)#">
<body>
<h3>This is a test of some simple output</h3>
<cfoutput>
This page was generated at #now()#<br>
</cfoutput>
<cfparam name = "URL.x" default = "no URL parm passed">
<cfoutput>The value of URL.x = # URL.x #</cfoutput>