[[[ iviewweb | Up To iView 5 Web Interface ]]] ====== Using *EXPRESSION in Virtual Folders ====== Using the *EXPRESSION rule type, you may key up to 1024 characters of valid Php code in the 'Comparison Value' field. iView 5 will feed this string to the Php eval() function and return its value. * The code must be valid Php. * Do not enclose the code in quotes - eval() would evaluate that as a string and return NULL. * You may reference the archive index field value using the variable **$fieldValue**. You may want to trim() this value. * The code must use **return**, and should return TRUE, FALSE, or something that the Php interpreter will evaluate to TRUE or FALSE. * **Prefix all variables you use**, except $fieldValue, with u_. Thus you might have variables named $u_firstChar. This is to avoid name conflicts. Examples:


if( trim( $fieldValue ) == "Able Anderson" ) return TRUE; else return FALSE;


$u_firstChar = substr( trim( $fieldValue ), 0, 1 );
 
if( $u_firstChar == 'C' || $u_firstChar == 'D' ) return TRUE; else return FALSE;

A rules specification for the above would look thus: {{pub:iview:vfexpression600.png|}} For more information see [[http://us.php.net/manual/en/function.eval.php]] The ability to paste any Php code into this field is a glaring security and data integrity issue and administration of Virtual Folders should be restricted as appropriate.

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