Template:If blank/doc

Purpose: when used as a template output for a query, makes show statements more readable. As a disadvantage, it handles only inline results with a single report property.

Discussion: The inline query parameter "default" is somewhat nonintuitive. It does not fire when there is no text, it fires when the query portion of the statement fails. They are not the same. Consider the following example article that does not have a birth locality property set:


 *   returns ""
 * This query does not display "unknown locality" as one might suspect. Instead it displays a null.  This is because the query portion actually succeeded.  There is indeed an article "Abraham Hunsberger (1786-1860)", so for that reason default text was not invoked. To get default to fire, we must construct a query that will fail.  We ask for birth locality to also have some value.:
 *   returns ""
 * This presents intimidating syntax for contributors. It would be possible to do a template such as
 *   returns ""
 * Where template if blank simply prints value of parameter "return" if there result of the query is blank.