Question

我想为函数参数化XPATH过滤器，但是希望有机会指出我想要所有结果。清楚的例子

declare function search-by-author($author as xs:string*) as element()*{
   /Data/Books[@autor=$author]
};

search-by-author(()) -> If null no results even if some books did not have @autor attr
search-by-author('') -> If empty, only shows those books with @author=''
search-by-author(('a','b')) -> Returns books by authors 'a' or 'b'
search-by-author(*) -> THIS MY CURRENT PROBLEM.

我怎么能模仿这个？有没有特殊的参数或语法来传递*作为变量，所以我可以做

 $var = * --> /Data/Books[@autor=$var]

或

 $var = EMPTY --> /Data/Books[@autor=$var] --> /Data/Books[@autor]

谢谢！

Answer 1

使用

declare function search-by-author($author as xs:string*) as element()*{
   /Data/Books[$author='*' or @autor=$author]
};

你可以做到

search-by-author('*')

xQuery变量持有通配符*（任何）

1 个答案: