Marklogic-如何在Xquery中分配动态变量 [英] Marklogic - How to assign dynamic variable in Xquery

问题描述

我尝试了下面提到的XQuery.

I have tried below mentioned XQuery .

declare variable $path  as xs:string :="D:\Mongo\";

    let $uri :="/MJ/1932/Vol1/Part1/387.xml"
    let $x := fn:normalize-space(fn:replace($uri,"/"," "))
    for $i in fn:tokenize($x, " ")
    let $j := fn:concat($path,$i)
    return($j)

实际输出

    D:\Mongo\MJ
    D:\Mongo\1932
    D:\Mongo\Vol1
    D:\Mongo\Part1
    D:\Mongo\387.xml

预期输出

D:\Mongo\MJ
D:\Mongo\MJ\1932
D:\Mongo\MJ\1932\Vol1
D:\Mongo\MJ\1932\Vol1\Part1
D:\Mongo\MJ\1932\Vol1\Part1\387.xml

请建议我，如何更改动态变量值.

Please Suggest me , how to change the dynamically variable value.

推荐答案

XQuery是一种功能编程语言，它暗示变量是不可变的.您不能简单地增加或附加到已定义的变量.通常，使用递归函数来构造结果.

XQuery is a functional programming language, which implies variables are immutable. You cannot simply increment or append to a defined variable. Typically, a recursive function is used instead to construct the result.

此示例(有更多简洁的示例，我想使各个部分分开并易于理解)以递归方式创建路径，每次执行时都附加一个级别. $path前缀是单独添加的，以免混淆不同的任务.

This examples (there are more concise ones, I wanted to keep the individual parts split apart and simple to understand) recursively creates the path, appending another level each time executed. The $path prefix is appended separately to not mix up the different tasks.

declare variable $path  as xs:string :="D:\Mongo\";
declare variable $uri as xs:string := "/MJ/1932/Vol1/Part1/387.xml";

declare function local:add-path($parts as xs:string*) as xs:string* {
  let $head := $parts[1]
  let $tail := $parts[position() > 1]
  return
    if ($head)
    then (
      $head,
      for $path in local:add-path($tail)
      return string-join(($head, $path), "\")
    )
    else ()

};

for $uri in local:add-path(fn:tokenize(fn:normalize-space(fn:replace($uri,"/"," ")), " "))
return concat($path, $uri)

在这种情况下，另一种方法是在位置计数器上循环并将零件连接到该位置:

In this specific case, an alternative would be to loop over a position counter and join the parts up to this position:

declare variable $path  as xs:string :="D:\Mongo\";
declare variable $uri as xs:string := "/MJ/1932/Vol1/Part1/387.xml";

let $parts := fn:tokenize(fn:normalize-space(fn:replace($uri,"/"," ")), " ")
for $i in (1 to count($parts))
return concat($path, string-join($parts[position() <= $i], '\'))

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