assign
Synopsis
<#assign name=value>
or
<#assign name1=value1 name2=value2 ... nameN=valueN>
or
<#assign same as above... in namespacehash>
or
<#assign name>
capture this
</#assign>
or
<#assign name in namespacehash>
capture this
</#assign>
Where:
-
name: name
of the variable. It is not expression. However, it can be
written as a string literal, which is useful if the variable
name contains reserved characters, for example
<#assign "foo-bar" = 1>. Note that this
string literal does not expand interpolations (as
"${foo}"); if you need to assign to a
dynamically constructed name, the you have to use this
trick.
-
value: the
value to store. Expression.
-
namespacehash:
a hash that was created for a namespace (by import).
Expression.
Description
With this you can create a new variable, or replace an
existing variable. Note that only top-level variables can be
created/replaced (i.e. you can't create/replace
some_hash.subvar, but
some_hash).
For more information about variables, read this: Template Author's Guide/Miscellaneous/Defining variables in the template
Example: variable seasons will store a
sequence:
 | | |
|
<#assign seasons = ["winter", "spring", "summer", "autumn"]> |
| |
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Example: Increments the numerical value stored in variable
test:
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<#assign test = test + 1> |
| |
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As a convenience feature, you can do more assignments with one
assign tag. For example this will do the same as
the two previous examples:
| | |
|
<#assign
seasons = ["winter", "spring", "summer", "autumn"]
test = test + 1
> |
| |
| | |
If you know what namespaces are: assign
directive creates variables in namespaces. Normally it creates the
variable in the current namespace (i.e. in the namespace associated
with the template where the tag is). However, if you use in
namespacehash then you can
create/replace a variable of another namespace than the current
namespace. For example, here you create/replace variable
bgColor of the namespace used for
/mylib.ftl:
| | |
|
<#import "/mylib.ftl" as my>
<#assign bgColor="red" in my> |
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An extreme usage of assign is when it
captures the output generated between its start-tag and end-tag.
That is, things that are printed between the tags will not be shown
on the page, but will be stored in the variable. For example:
| | |
|
<#macro myMacro>foo</#macro>
<#assign x>
<#list 1..3 as n>
${n} <@myMacro />
</#list>
</#assign>
Number of words: ${x?word_list?size}
${x} |
| |
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will print:
| | |
|
Number of words: 6
1 foo
2 foo
3 foo
|
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Please note that you should not to use this to insert
variables into strings:
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<#assign x>Hello ${user}!</#assign> <#-- BAD PRACTICE! --> |
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You should simply write:
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<#assign x="Hello ${user}!"> |
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