Setting cache dependencies

Cache dependencies allow the application to automatically clear cached data when related objects are modified.

The system uses dummy cache keys to create dependencies between cached data and other objects. Dummy keys are cache items without any data that represent objects or groups of objects. When an object is modified, the system "touches" the corresponding dummy keys, which causes the cache to delete all items that depend on the given dummy keys.

Sample scenario

A page with the /Products alias path contains a Repeater web part with content caching enabled. The repeater displays a list of products (pages) placed under the Products page. When a visitor requests the Products page, the repeater loads the list of products from the database, and stores the data in the content cache. The cached data has a dependency on the node|corporatesite|/products|childnodes dummy key, which the system automatically creates. If a child page of the Products page is modified, the dummy key is touched, and the cache deletes the dependent data.

The following table shows which dummy cache keys are touched when objects are modified:

Object type Touched dummy keys Sample dummy key values

Pages
(content tree nodes)

node|<site name>|<alias path>|<culture>
node|<site name>|<alias path>
nodeid|<node id>
nodeid|<linked node id>
documentid|<document id>
documentid|<document id>|attachments
nodes|<site name>|<page type code name>|all
nodeguid|<site name>|<node guid>

+ for all ancestors of the modified page:
node|<site name>|<alias path>|childnodes

node|corporatesite|/home|en-us
node|corporatesite|/home
nodeid|12
nodeid|34
documentid|39
documentid|39|attachments
nodes|corporatesite|cms.menuitem|all
nodeguid|corporatesite|a58ed488-5545-48d0- ...

node|corporatesite|/|childnodes

Objects
(not pages)

<object type>|all
<object type>|byid|<id>
<object type>|byname|<code name>
<object type>|byguid|<guid>

Tip: You can find the object type values in the System application on the Object types tab.

cms.user|all
cms.user|byid|53
cms.user|byname|administrator
cms.user|byguid|1ced44f3-f2fc- ...

Metafiles

metafile|<guid>

metafile|1ced44f3-f2fc- ...
Page attachments

cms.attachment|all
documentid|<attachment document id>
documentid|<attachment document id>|attachments
attachment|<guid>

cms.attachment|all
documentid|32
documentid|32|attachments
attachment|1ced44f3-f2fc- ...

Page relationships

nodeid|<node id>|relationships nodeid|5|relationships
Forum attachments forumattachment|<guid> forumattachment|1ced44f3-f2fc- ...
Avatars avatarfile|<guid> avatarfile|1ced44f3-f2fc- ...
Media files mediafile|<guid>
mediafile|preview|<guid>
mediafile|1ced44f3-f2fc- ...
mediafile|preview|1ced44f3-f2fc- ...
Page templates template|<id> template|12
Custom table data records

customtableitem.<custom table code name>|all
customtableitem.<custom table code name>|byid|<id>

customtableitem.customtable.sampletable|all
customtableitem.customtable.sampletable|byid|2

Dependencies on form data records

The system currently does not touch any dummy cache keys when changes occur for data submitted via forms.

As a workaround, developers can prepare custom event handlers for BizFormItemEvents. Use the handler method to touch a custom cache key, and then enter the key into your cache dependencies. For example:

private void FormItem_InsertAfterHandler(object sender, BizFormItemEventArgs e)
{
	// Touches a custom cache key, for example: "customformdata|bizform.contactus"
	CacheHelper.TouchKey("customformdata|" + e.Item.BizFormClassName);
}

Adding custom cache dependencies

You can set custom cache dependencies for the following types of cache:

Create the dependencies by typing the names of dummy cache keys into the appropriate Cache dependencies property. Each dummy key must be on a separate line when entering dependencies in the web part properties dialog. The system automatically clears the related cache when the specified dummy keys are touched (i.e. when the corresponding objects are modified).

Examples

Scenario: You have a web part displaying information about users. You need to clear the web part's partial output cache whenever one of the user's data is modified.

Solution: Add the cms.user|all dummy key into the web part's Partial cache dependencies property. The system touches this dummy key whenever the data of a user in the system changes.

Scenario: You have a web part displaying information about one specific user — the administrator (UserID is 53, UserGuid is 849711D0-739D-412E-92B6-FE40EDCADC4A). You need to clear the web part's partial output cache when the administrator's user account data is modified.

Solution: Add any of the following dummy keys into the web part's Partial cache dependencies property:

  • cms.user|byid|53
  • cms.user|byname|administrator
  • cms.user|byguid|849711D0-739D-412E-92B6-FE40EDCADC4A

Scenario: You have a web part displaying a list of news articles. The web part loads the data from all CMS.News pages on the website. The site's code name is NewsSite. You need to clear the web part's partial output cache when any of the news pages is updated.

Solution: Add the nodes|newssite|cms.news|all dummy key into the web part's Partial cache dependencies property.


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