我可以在与XQJ绑定的变量中让XQuery评估{$ expression}吗? [英] Can I make XQuery evaluate { $expression } within variables bound with XQJ?
问题描述
要模拟XQuery Update中的自动增量值,在第一次运行<root count="0"/>
的情况下,以下操作可以正常工作:
To mimic an auto-increment value in XQuery Update, the following works fine, assuming <root count="0"/>
when running this for the first time:
let $count := /root/@count
return (
insert node <node id='{ $count }'/> into /root,
replace value of node $count with $count + 1
)
...很好地屈服:
<root count="1">
<node id="0">
</root>
However, I'd like to define the node in my Java code, and then bind that as an org.w3c.dom.Node
or Document
, or even String
. Like:
String expr =
" declare variable $n external; "
+ " let $count := /root/@count; "
+ " return ( "
+ " insert node $n into /root, "
+ " replace value of node $count with $count + 1 "
+ " ) ";
XQConnection xqc = ...;
XQPreparedExpression xqp = xqc.prepareExpression(expr);
// org.w3c.dom.Node node is <node id='{ $count }'/>
xqp.bindNode(new QName("n"), node, null);
xqp.executeQuery();
但是,这只是在属性中留下了文本 { $count }
.将节点绑定为xs:string
值具有相同的效果.
However, this just leaves me the text { $count }
in the attribute. Binding the node as an xs:string
value has the same effect.
当然,这是防止"XQuery注入"的好方法.还有:是否有任何方法可以使XQuery Update进程成为我在变量本身中包含的括起来的表达式?
Of course, this is a nice protection against "XQuery injection". Still then: is there any way to make XQuery Update process an enclosed expression I have in the variables themselves?
(也非常欢迎在XQuery中使用自动增量值的任何其他聪明的主意,但请参见
(Any other smart ideas to use auto-increment values in XQuery are very welcome too, but then see Auto increment with XQuery Update?)
推荐答案
说到注入...为什么不只是将节点作为字符串传递并使用basex:eval()?
Speaking of injection...why not just pass the node as a string and use basex:eval()?
String node = "<node id='{ $count }'/>";
String expr =
...
+ " insert node xquery:eval($n) into /root, "
...
上方,xquery:
指的是BaseX模块.
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