Special Variable Reference

Special variables are variables defined by the FreeMarker engine itself. To access them, you use the .variable_name syntax. For example, you can't write simply version; you have to write .version.

Note:

As of FreeMarker 2.3.23, you can use camel case instead of snake case for special variable names, like dataModel instead of data_model. But know that then within the same template, FreeMarker will enforce the usage of camel case for all identifiers that are part of the template language (user defined names are not affected).

The supported special variables are:

  • auto_esc (since 2.3.24): Boolean value that tells if auto-escaping (based on output format) is on or off at the place where this variable is referred (resolved statically). This is not affected by the deprecated escape directive. This only deals with automatic escaping based on the output format mechanism.
  • caller_template_name (available since FreeMarker 2.3.28): Returns the name (path) of the template from which the current macro or function was called. It's mostly useful if you want to resolve paths relative to the caller template (see an example here). To serve that purpose better, if the caller template is nameless, this will be an empty string (not a missing value). Reading this variable will cause error if you aren't inside a macro or function call. In particular, directives and "methods" implemented in Java will not influence the value of this variable; it's only for macros and functions implemented in templates. (TemplateDirectiveModel implementations can get similar information via the freemarker.core.DirectiveCallPlace object.)
  • current_template_name: The name of the template where we are now (available since FreeMarker 2.3.23). This can be missing (null) if the template was created on-the-fly in Java (via new Template(null, ...)), rather than loaded from a backing store by name (via cfg.getTemplate(name, ...)). Migration notice: If you replace the deprecated template_name with this, note that the later is a 0-length string instead of missing (null) if the template has no name, so you might want to write current_template_name!'' in legacy templates.
  • data_model: A hash that you can use to access the data-model directly. That is, variables you did with global directive are not visible here.
  • error (available since FreeMarker 2.3.1): This variable accessible in the body of the recover directive, where it stores the error message of the error we recover from.
  • globals: A hash that you can use to access the globally accessible variables: the data-model and the variables created with global directive. Note that variables created with assign or macro are not globals, thus they never hide the variables when you use globals.
  • incompatible_improvements (since FreeMarker 2.3.24): The incompatible_improvements setting of the current FreeMarker configuration, as a string.
  • lang: Returns the language part of the current value of the locale setting. For example if .locale is en_US, then .lang is en.
  • locale: Returns the current value of the locale setting. This is a string, for example en_US. For more information about locale strings see the setting directive.
  • locale_object (available since FreeMarker 2.3.21): Returns the current value of the locale setting as a java.util.Locale object, rather than as a string. This meant to be used instead of .locale when you want to pass it as a java.util.Locale object to a Java method. (The Locale object will be wrapped according the object_wrapper setting value. Whether you can actually pass this value to a Java method as a Locale object depends on the object wrapper, but an object wrapper that let you call Java methods directly is very unlikely to not support that.)
  • locals: A hash that you can use to access the local variables (the variables created with the local directive, and the parameters of macro).
  • main: A hash that you can use to access the main namespace. Note that global variables like the variables of data-model are not visible through this hash.
  • main_template_name: The name of the top level template (available since FreeMarker 2.3.23). (In Java, this is the template for which Template.process was called.) This can be missing (null) if the template was created on-the-fly in Java (via new Template(null, ...)), rather than loaded from a backing store by name (via cfg.getTemplate(name, ...)). Migration notice: If you replace the deprecated template_name with this, note that the later is a 0-length string instead of missing (null) if the template has no name, so you might want to write main_template_name!'' in legacy templates.
  • namespace: A hash that you can use to access the current namespace. Note that global variables like the variables of data-model are not visible through this hash.
  • node (alias current_node for historical reasons): The node you are currently processing with the visitor pattern (i.e. with the visit, recurse, ...etc. directives). Also, it initially stores the root node when you use the FreeMarker XML Ant task.
  • now: Returns the current date-time. Usage examples: "Page generated: ${.now}", "Today is ${.now?date}", "The current time is ${.now?time}".
  • Returns the name of the current output format. This value is never missing/null. It's maybe the string "undefined", which is just the name of the default output format.
  • output_encoding (available since FreeMarker 2.3.1): Returns the name of the current output charset. This special variable is not existent if the framework that encapsulates FreeMarker doesn't specify the output charset for FreeMarker. (Programmers can read more about charset issues here...)
  • get_optional_template: This is a method that's used when you need to include or import a template that's possibly missing, and you need to handle that case on some special way. More details...
  • pass: This is a macro that does nothing. It has no parameters. Mostly used as no-op node handler in XML processing.
  • template_name: Don't use it, because its behavior is strange when macros are used; use current_template_name or main_template_name instead (see migration notices there). Gives the name of the main template, or if we are running an included or imported template, the name of that template. When calling macros, it becomes rather confusing: the macro call won't change the value of this special variable, but when nested is called, it changes it to the name of the template that belongs to the current namespace. (Available since FreeMarker 2.3.14.)
  • url_escaping_charset (available since FreeMarker 2.3.1): If exists, it stores the name of the charset that should be used for URL escaping. If this variable doesn't exist that means that nobody has specified what charset should be used for URL encoding yet. In this case the url built-in uses the charset specified by the output_encoding special variable for URL encoding; custom mechanism may follow the same logic. (Programmers can read more about charset issues here...)
  • output_format (since 2.3.24): The name of output format at the place where this variable is referred (resolved statically), such as "HTML", "XML", "RTF", "plainText", "undefined", etc. (The available names can be extended by the programmers, by the registered_custom_output_formats setting.)
  • vars: Expression .vars.foo returns the same variable as expression foo. It's useful if for some reasons you have to use square bracket syntax, since that works only for hash sub variables, so you need an artificial parent hash. For example, to read a top-level variable that has a strange name that would confuse FreeMarker, you can write .vars["A strange name!"]. Or, to access a top-level variable with dynamic name given with variable varName you can write .vars[varName]. Note that the hash returned by .vars does not support ?keys and ?values.
  • version: Returns the FreeMarker version number as string, for example 2.2.8. This can be used to check which FreeMarker version does your application use, but note that this special variable does not exist prior to the 2.3.0 or 2.2.8 versions. The version number of non-final releases contains dash and further info after the numbers, like in 2.3.21-nightly_20140726T151800Z.

Using get_optional_template

This special variable is used when you need to include or import a template that's possibly missing, and you need to handle that case on some special way. It a method (so you meant to call it) that has the following parameters:

  1. The name of the template (can be relative or absolute), like "/commonds/footer.ftl"; similar to the first parameter of the include directive. Required, string.

  2. An optional hash of options, like { 'parse': false, 'encoding': 'UTF-16BE' }. The valid keys are encoding and parse. The meaning of these are the same as of the similarly named include directive parameters.

This method returns a hash that contains the following entries:

  • exists: A boolean that tells if the template was found.

  • include: A directive that, when called, includes the template. Calling this directive is similar to calling the include directive, but of course with this you spare looking up the template again. This directive has no parameters, nor nested content. If exists is false, this key will be missing; see later how can this be utilized with the exp!default operator.

  • import: A method that, when called, imports the template, and returns the namespace of the imported template. Calling this method is similar to calling the import directive, but of course with this you spare looking up the template again, also, it doesn't assign the namespace to anything, just returns it. The method has no parameters. If exists is false, this key will be missing; see later how can this be utilized with the exp!default operator.

When this method is called (like .get_optional_template('some.ftl')), it immediately loads the template if it exists, but doesn't yet process it, so it doesn't have any visible effect yet. The template will be processed only when include or import members of the returned structure is called. (Of course, when we say that it loads the template, it actually looks it up in the template cache, just like the include directive does.)

While it's not an error if the template is missing, it's an error if it does exist but still can't be loaded due to syntactical errors in it, or due to some I/O error.

Note:

If the template fails with "I/O error when trying to load optional template" when the template is missing, that's often because your application uses a custom freemarker.cache.TemplateLoader implementation, which incorrectly (against the API documentation) throws an IOException in the findTemplateSource method instead of returning null if a template is not found. If it's so, the Java programmers need to fix that. Another possibility is of course that it was indeed not possible to tell if the template exists or not due to some technical issues, in which case stopping with error is the correct behavior. See the cause IOException in the Java stack trace to figure out which case it is.

Example, in which depending on if some.ftl exists, we either print "Template was found:" and the include the template as <#include 'some.ftl'> would, otherwise it we print "Template was missing.":

<#assign optTemp = .get_optional_template('some.ftl')>
<#if optTemp.exists>
  Template was found:
  <@optTemp.include />
<#else>
  Template was missing.
</#if>

Example, in which we try to include some.ftl, but if that's missing then we try to include some-fallback.ftl, and if that's missing too then we call the ultimateFallback macro instead of including anything (note the !-s after the include-s; they belong to the exp!default operator):

<#macro ultimateFallback>
  Something
</#macro>

<@(
  .get_optional_template('some.ftl').include!
  .get_optional_template('some-fallback.ftl').include!
  ultimateFallback
) />

Example, which behaves like <#import 'tags.ftl' as tags>, except that if tags.ftl is missing, then it creates an empty tags hash:

<#assign tags = (.get_optional_template('tags.ftl').import())!{}>