Velocity language

The Velocity engine used in Telosys is version 1.7

For more information about the Velocity Templates Language (VTL) see the official web site :

• User guide : http://velocity.apache.org/engine/releases/velocity-1.7/user-guide.html

• Reference guide : http://velocity.apache.org/engine/releases/velocity-1.7/vtl-reference-guide.html

References

A template is a text file mixing fixed parts and dynamic parts based on references to variables and objects. A reference to a variable or an object starts with "$".

Exemple :

• $foo : content of variable "foo"

• $customer.address : get property "address" in object "customer"

• $person.isVIP() : call method "isVIP()" in object "person"

In some cases "Formal Reference Notation" with "${xxx}" is required to avoid ambiguities. Examples :

• ${foo}

• ${customer.address}

• ${person.isVIP()}

Examples :

Current entity is ${entity.name}

#foreach( $attrib in $entity.attributes )
  Do something with $attrib.name and $attrib.type
#end

Comments

A line starting with "##" is a comment. All lines between "#*" and "*#" are a comment block.

## This is a single line comment.

#*
This is a multi-lines comment
with 1 to N lines
*#

Literals

String literals

When using the #set directive, strings that are enclosed in double quote characters will be parsed. But if the string literal is enclosed in single quote characters, it will not be parsed. A string literal can contains multiple lines.

#set($s = "abc $i")## 'i' is replaced by its value

#set($s = 'abc $i')## no variable substitution

#set($s = 
'line 1 $a
line 2 $b
line 3 $c')## 3 lines in the string

Unparsed content

The #[[ do not parse me ]]# syntax allows to easily use large chunks of uninterpreted and unparsed content in a template.

#[[
Unparsed block (all this block will be rendered as is)
$undefined
#set($i = 50)
#foobar #zzz(ee)
#include("foo.txt")
]]#

Operators

Comparison operators

Examples (showing different operators):

Operator	Symbol	Text	Example
Equals / number	==	eq	#if( $foo == 42 )
Equals / string	==	eq	#if( $foo == "bar" )
Equals / object	==	eq	#if( $foo == $bar )
Not Equals	!=	ne	#if( $foo != $bar )
Greater Than	>	gt	#if( $foo > 42 )
Less Than	<	lt	#if( $foo < 42 )
Greater Than or Equal To	>=	ge	#if( $foo >= 42 )
Less Than or Equal To	<=	le	#if( $foo <= 42 )

Note: The == operator can be used to compare numbers, strings, objects of the same class, or objects of different classes. In the last case (when objects are of different classes), the toString() method is called on each object and the resulting Strings are compared.

Logical operators

Operator	Symbol	Text
Logical AND	&&	and
Logical OR	||	or
Logical NOT	!	not

Examples :

#if ( $v > 100 && $v < 200 )
Between 100 and 200 
#end 

#if ( $v == 100 || $v == 102 || $v == 123 )
Var is 100 or 102 or 123 
#end 

#if ( ! ( $v == 100 || $v == 101 ) )
Var is not 100 or 101
#end 

Arithmetic operators

Operator	Symbol	Example
Addition	+	#set( $r = $a + $b )
Subtraction	-	#set( $r = $a - $b )
Multiplication	*	#set( $r = $a * $b )
Division	/	#set( $r = $a / $b )
Modulo	%	#set( $r = $a % 10 )
Increment	(no operator)	#set( $a = $a + 1 )
Decrement	(no operator)	#set( $a = $a - 1 )

Note: when the "+" operator is used with 2 strings, it concatenates these 2 strings.

Range operator

The range operator creates an array of integer objects. It can be used in conjunction with #set and #foreach statements. Syntax : [ first .. last ]

Examples :

## Range from 1 to 5
#foreach( $i in [1..5] )
  $i
#end

## Range from 10 to 12 (size : 3 )
#set( $r = [ 10 .. 12 ] )
range size : $r.size()
#foreach( $i in $r )
  $i
#end

## Range from var to var
#set( $a = 4 )
#set( $b = 8 )
#foreach( $i in [$a..$b] )
  $i
#end

## Range in reverse order
#foreach( $i in [ 4 .. -2 ] )
  $i
#end