IF Statements

The %IF% construct gives Foswiki the power to include content in topics based on the value of simple expressions.

On this page:

Syntax
- Examples
Context identifiers
Query syntax
- Examples

Syntax

%IF{"CONDITION" then="THEN" else="ELSE"}%

In the example above, if CONDITION evaluates to TRUE, then THEN will be included in the topic; otherwise ELSE will be included.

Note that because of the way Foswiki evaluates, then whatever is in the THEN and ELSE parameters will already have been expanded by the time the condition is actually evaluated. The standard Format Tokens can be used in the THEN and ELSE parameters when you need to delay evaluation of (for example) a macro.

The basic syntax of a condition is the same as the syntax used for queries, with the addition of the following special operators:

`context`	True if the current context is set (see below)
`allows`	`'X' allows 'Y'` is true if web/topic 'X' exists and allows access mode 'Y' for the current user. Web access rights are only checked if there is no topic called 'X'.
`istopic`	`istopic 'X'` is true if topic 'X' exists
`isweb`	`isweb 'X'` is true if web 'X' exists
`ingroup`	`'X' ingroup 'Y'` is true if user 'X' is in group 'Y'. 'X' can be a login name or a wikiname.
`defined`	True if a preference setting or url parameter of this name is defined.
`isempty`	True if a preference setting, url parameter or session variable of this name has an empty value. It is equivalent to the expression `(defined(x) \|\| $x='')`
`$`	expands a URL parameter or macro name. Plugin handlers are not called. You can pass a limited subset of parameters to macros by enclosing the parameter string in single quotes; for example, `$ 'MACRO{value}'`. The `'MACRO{value}'` string may not contain quotes (' or ").

Examples

1. Macro defined or not

%IF{
   "defined 'WIKINAME'"
   then="WIKINAME is defined"
   else="WIKINAME is not defined"
}%

2. Compare macro definition

You are %IF{
   "$ WIKINAME='WikiGuest' and not defined 'OPEN_DAY'"
   then="not"
}% allowed to
%IF{
   "context view"
   then="view"
   else="edit"
}% this Foswiki today.

3. URL parameter

%IF{
   "defined 'search'"
   then="Search: $percentURLPARAM{search}$percent"
   else="No search passed in"
}%

4. Range test on URL parameter

url param t is %IF{
   "0 < $ t and $ t < 1000"
   then="in"
   else="out of"
}% range.

5. Text comparison of URL parameter

%IF{
   "$'URLPARAM{scope}'='text'"
   then="Plain text search"
}%

6. Configuration item set or not (item must be one of {ScriptSuffix}, {LoginManager}, {AuthScripts}, {LoginNameFilterIn}, {AdminUserLogin}, {AdminUserWikiName}, {SuperAdminGroup}, {UsersTopicName}, {AuthRealm}, {MinPasswordLength}, {Register}{AllowLoginName}, {Register}{EnableNewUserRegistration}, {Register}{NeedVerification}, {Register}{RegistrationAgentWikiName}, {AllowInlineScript}, {DenyDotDotInclude}, {UploadFilter}, {NameFilter}, {AccessibleCFG}, {AntiSpam}{EmailPadding}, {AntiSpam}{HideUserDetails}, {AntiSpam}{RobotsAreWelcome}, {Stats}{TopViews}, {Stats}{TopContrib}, {Stats}{TopicName}, {UserInterfaceInternationalisation}, {UseLocale}, {Site}{Locale}, {Site}{CharSet}, {DisplayTimeValues}, {DefaultDateFormat}, {Site}{LocaleRegexes}, {UpperNational}, {LowerNational}, {PluralToSingular}, {EnableHierarchicalWebs}, {WebMasterEmail}, {WebMasterName}, {NotifyTopicName}, {SystemWebName}, {TrashWebName}, {SitePrefsTopicName}, {LocalSitePreferences}, {HomeTopicName}, {WebPrefsTopicName}, {UsersWebName}, {TemplatePath}, {LinkProtocolPattern}, {NumberOfRevisions}, {MaxRevisionsInADiff}, {ReplaceIfEditedAgainWithin}, {LeaseLength}, {LeaseLengthLessForceful}, {Plugins}{WebSearchPath}, {PluginsOrder}, {Cache}{Enabled}, {Validation}{Method}, {Register}{DisablePasswordConfirmation})

User details are %IF{
   "{AntiSpam}{HideUserDetails}"
   then="hidden"
   else="shown"
}%

expands to: User details are hidden

7. Plugin enabled test

TablePlugin is %IF{
   "context TablePluginEnabled"
   then="enabled"
   else="disabled"
}%.

expands to:
Table Plugin is enabled.

8. Check access permissions

You %IF{"'%TOPIC%' allows 'change'" then="can" else="cannot"}% change this topic.
You %IF{"'Sandbox.TestTopic' allows 'change'" then="can" else="cannot"}% change Sandbox.TestTopic.
You %IF{"'Sandbox' allows 'change'" then="can" else="cannot"}% change Sandbox web

expands to:
You cannot change this topic. You can change Test Topic?. You can change Sandbox web

9. Check topic existance

Topic Sandbox.TestTopic %IF{"istopic 'Sandbox.TestTopic'" then="exists" else="does not exist"}%
Web Sandbox.TestTopic %IF{"isweb 'Sandbox'" then="exists" else="does not exist"}%

expands to:
Topic Test Topic? does not exist Web Test Topic? exists

10. Group membership

You are %IF{
   "'%USERNAME%' ingroup 'AdminGroup'"
   then="an admin"
   else="a normal user"
}%

expands to:
You are a normal user

Configuration items are defined in configure. You cannot see the value of a configuration item, you can only see if the item is set or not.

Context identifiers

Context identifiers are used in Foswiki to label various stages of the rendering process. They are especially useful for skin authors to find out where they are in the rendering process. The following context identifiers are available:

id	context
`absolute_urls`	Set if absolute URLs are required
`attach`	in attach script (see Command And CGIScripts)
`authenticated`	a user is authenticated
`body_text`	when the body text is being processed in a view (useful in plugin handlers)
`can_login`	current environment supports login
`changes`	in changes script (see Command And CGIScripts)
`command_line`	the running script was run from the command line, and not from CGI
`diff`	in rdiff script (see Command And CGIScripts)
`edit`	in edit script (see Command And CGIScripts)
`footer_text`	when the footer text is being processed in a view (useful in plugin handlers)
`header_text`	when the header text is being processed in a view (useful in plugin handlers)
`i18n_enabled`	when user interface I18N support is enabled (i.e., user can choose the language for UI)
`inactive`	if active links such as 'edit' and 'attach' should be disabled
`login` and `logon`	in login / logon script (see Command And CGIScripts)
`manage`	in manage script (see Command And CGIScripts)
`mirror`	if this is a mirror
`new_topic`	if the topic doesn't already exist
`oops`	in oops script (see Command And CGIScripts)
`preview`	in preview script (see Command And CGIScripts)
`register`	in register script (see Command And CGIScripts)
`rename`	in rename script (see Command And CGIScripts)
`resetpasswd`	in resetpasswd script (see Command And CGIScripts)
`rss`	if this is an RSS skin rendering
`save`	in save script (see Command And CGIScripts)
`search`	in search script (see Command And CGIScripts)
`statistics`	in statistics script (see Command And CGIScripts)
`textareas_hijacked`	provided for use by editors that highjack textareas, and want to signal this fact. This is used by skins, for example, so they can suppress extra controls when textareas have been hijacked.
`upload`	in upload script (see Command And CGIScripts)
`view`	in view script (see Command And CGIScripts)
`viewfile`	in viewfile script (see Command And CGIScripts)
`rest`	in rest script (see Command And CGIScripts)
`registration_supported`	registration is supported by the current User Mapper?
`registration_enabled`	set if `{Register}{EnableNewUserRegistration}` is on, and registrationis supported
`passwords_modifyable`	set if the password manager supports changing the password / email

In addition there is a context identifier for each enabled plugin; for example, if GallousBreeksPlugin is installed and enabled, then the context ID GallousBreeksPluginEnabled will be set. Other extensions may set additional context identifiers.

The %IF% statement is deliberately kept simple. In particular, note that there is no way to conditionally execute a Set statement. If you need more sophisticated control over formatting, then consider using the Spread Sheet Plugin.

Query syntax

Note that while the query syntax can be used to access form fields, there are some contexts in which an IF statement may be used where there is no topic context, or the topic context is not what you want. In these cases you can use the / operator to indicate the name of the topic:

Examples

Display the value of a form field if the topic has form field "Summary":

%FORMFIELD{
   "%IF{
      "'%TOPIC%'/Summary"
      then="Summary"
   }%"
}%

The IF macro is expanded before FORMFIELD. Read more

Test if the topic has attachments:

%IF{
   "'%TOPIC%'/attachments"
   then="has attachments"
}%

Test if the topic has an attachment with 'receipt' or 'Receipt' in the name:

%IF{
   "'%TOPIC%'/attachments[lc(name)~'*receipt*']"
   then="has 'receipt' attachment"
}%

Test if a topic text contains a certain word:

%IF{
   "'%SYSTEMWEB%.WebHome'/lc(text)~'*welcome*'"
   then="contains 'welcome'"
}%

Wiki Tools

IF Statements

Syntax

Examples

Context identifiers

Query syntax

Examples