java - Template recursive structure with apache velocity -

i have recursive data structure, tree, node may have child nodes , on. i'm trying generate json-like file of structure. thought of using #parse directive. in context store root node , in templatename template's name.

{     "name" = "$node.name",     "value" = "$node.value"      #if ($node.childrens.size() > 0)     ,     "childrens" = {         #foreach ($child in $node.childrens)             ## next statement not work             #parse ($child.type + ".vm", $child)         #end     }     #end } 

the apache velocity documentation states #parse directive only takes 1 argument.

in examples have seen use of #set directive before calling template, if depth of tree higher 2 not work because variable used in #set directive stored in same context when going depth 1 2 variable overwritten.

the reason use #parse instead of macro suggested @sergiu dumitriu because each node may rendered in different way depending on it's property $node.type. have template each type 1 person adding template particular type not have mess other template, mean, maybe achieved having switch on type property; implies ways of rendering defined in same file.

is there way of using velocity apply templates recursive data structures?

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solution based on both answers sergiu dumitriu final template looks like:

#macro ( displaynode $node) {     #set ( $parsenode = $node )     #set ( $parsetemplate = $parsenode.type + ".vm" )     #parse ( $parsetemplate )     #set ( $parsenode = $node )     #set ( $parsetemplate = "common.vm" )     #parse ( $parsetemplate ) } #end 

the common.vm has structure shown in question.

you should not use #parse, since it's costly operation. define macro , use recursively instead.

#macro(displaynode $node) {     "name" = "$node.name",     "value" = "$node.value"##     #if ($node.childrens.size() > 0),     "childrens" = {         #foreach ($child in $node.children)             #displaynode($child)         #end     }     #end } #end 

if template name variable, can use #evaluate construct template name dynamically:

        #set ($d = '$')         #foreach ($child in $node.children)             #evaluate("#display${child.type}node(${d}child)")         #end