# OpenWGA 7.10 - WebTML reference

WebTML tags » [All tags]## <tml:[All tags] if ="itemexpression">

#### Purpose:

If the condition in the if Item-Expression is false the tag is not rendered.

May be combined with if_equals. In this case the item-expression is compared with this if_equal value to evaluate as true or false.

#### Description:

The "unless" expression has priority over the "if" expression. When both are present and evaluate true then the tag is cancelled.

#### Boolean item expression

A simple expression syntax to use WebTML items for evaluating a boolean result. Consisting of:- Item term: Just anything that is valid in this.item() as item name, like names of content items, WebTML variables, Renderer/Controller property expressions
- Boolean Operators: & being "and", | being "or", between those item terms. There may be only one type of boolean operator on one expression, so "a | b", "a & b & c" is valid, "a | b & c" is invalid.
- Brackets to form sub expressions, where again a single boolean operator can be used, differing from the one on the main expression: "(a | b) & c"
- Exclamation mark operators to negate either item expressions or sub expressions: "!a", "!(a & b)"
- Equals operator = being "equals". Must be the last operator in the expressen. Not valid in combination with if_equals.

If not used together with if_equals every item term is evaluated for its boolean value by the rules of TMLContext.isTrue(). Then the boolean values are combined in the ways determined by operators to form a result value.

If combined with if_equals or if equals operator (=) is used each item term is compared against the equals-expression and the results are combined in the ways determined by operators to form a final result value. So a&b=1 means a and b must be 1, a|b=1 means a or b must be 1.

#### Value(s):

#### Examples:

<tml:input name="product" if="products_available"/>

<tml:case if="$mc.value=100">...</tml:case>

<tml:case if="$mc-value" if_equals="100">...</tml:case>