If

Templating System : Designer Guide : Tag Reference : If

Summary

The if tag is used to output a template section only when certain conditions are met. It has the form <if expression>.

Expression Syntax

The expressions used in the <if> tag have the following form

x₀ [not] opx₁x₂ ...

The operator op determines the number operands (x ₀ , ... x _n-1 ).

The following operators are available:

• binary
  • x₀gt  x₁
  • x₀ge  x₁
  • x₀lt  x₁
  • x₀le  x₁
  • x₀eq  x₁
  • x₀ne  x₁
• n-ary
  • x₀in  x₁x₂x₃ ...
• ternary
  • x₀between  x₁x₂
• unary
  • x₀nil
  • x₀defined
  • x₀odd
  • x₀even
  • x₀true
  • x₀false

Any of these operators can be prefixed with not to invert the outcome.

Usage Examples

<if @x@ eq 5>True</if>
<if @x@ eq "Greta">True</if>

<if @x@ ne 5>True</if>
<if @x@ ne "Greta">True</if>

<if @x@ lt 5>True</if>
<if @x@ le 5>True</if>

<if @x@ gt 5>True</if>
<if @x@ ge 5>True</if>

<if @x@ true>True</if>
<if @x@ false>False</if>

<if @x@ odd>True</if>
<if @x@ even>True</if>

<if @x@ between 3 6>True</if>
<if @x@ not between 3 6>True</if>

<if @x@ eq 5 and @y@ eq 2>True</if>
<if @x@ ge 5 or @y@ le 2>True</if>

<if @s@ nil>True</if>
<if @s@ not nil>True</if>

<if @z@ in "Greta" "Fred" "Sam">True</if>
<if @z@ not in "Greta" "Fred" "Sam">True</if>

Notes

• Any legal variables that may be referenced in the template may also be used in if statements. Words not surrounded with the commercial at sign (@) are interpreted literally.

• Phrases with spaces in them must be enclosed in quotes to be grouped correctly:

    <if @datasource.variable@ eq "blue sky">
      <td bgcolor="#0000ff">
    </if>

• The elseif tag may be used following an if block to specify an alternate conditional template section.

    <if @datasource.variable@ eq "blue">
      <td bgcolor="#0000ff">
    </if>
    <elseif @datasource.variable@ eq "red">
      <td bgcolor=red>
    </elseif>
    <else>
      <td bgcolor="#ffffff">
    </else>

• The else tag may be used following an if block to specify an alternate template section when a condition is not true:

    <if @datasource.variable@ eq "blue">
      <td bgcolor="#0000ff">
    </if>
    <else>
      <td bgcolor="#ffffff">
    </else>

• Compound expressions can be created by combining terms with the and and or keywords, as illustrated above. Any number of statements may be connected in this fashion. There is no way to group statements to change the order of evaluation.

• When a variable is tested using the nil operator, it will return true if the variable is undefined or if the value of the variable is an empty string.

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