返回多元素 HTML 作为 xquery 结果

发布于 2024-10-17 18:50:03 字数 790 浏览 4 评论 0原文

我在返回多元素 HTML 结果时遇到问题（我不知道这个结果的名称）。为了更清楚地说明这一点，请参阅下面的代码。

<body>
  <h1>Nobel prize winners</h1>{
  for $subject in distinct-values(doc("nobel.xml")//subject)
    let $sn := $subject`
    return <div><h2>{$sn}</h2><ul>
       {for $row in doc("nobel.xml")/nobel/row
          let $name := $row/winner/text()
          let $year := $row/yr/text()
          where $row/subject/text()=$subject
          order by $year
          return <li> ({$year} {$name} </li>
        }</ul></div>
  }
</body>

该代码可以工作，但您可以注意到我必须将

和

放在 的开头和结尾return 部分，这是我实际上不想要的。我的问题是，有什么办法可以去掉吗？我尝试过 { } 和 ( ) ，但两者都不起作用。

原文

I have a problem with returning multi-element HTML result (I dont know the name for this). To make it clearer, please see the code below.

<body>
  <h1>Nobel prize winners</h1>{
  for $subject in distinct-values(doc("nobel.xml")//subject)
    let $sn := $subject`
    return <div><h2>{$sn}</h2><ul>
       {for $row in doc("nobel.xml")/nobel/row
          let $name := $row/winner/text()
          let $year := $row/yr/text()
          where $row/subject/text()=$subject
          order by $year
          return <li> ({$year} {$name} </li>
        }</ul></div>
  }
</body>

That code will work, but you can notice that I have to put that <div> and </div> in the beginning and the end of the return part, which I actually don't want. My question is, is there any way to remove it? I have tried with { } and ( ) and both don't work.

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去了角落 2024-10-24 18:50:03

以下是 XQuery 1.0 语法的语法规则，取自 XQuery 1.0 w3c 规范：

[31]    Expr          ::=    ExprSingle ("," ExprSingle)* 
[32]    ExprSingle    ::=    FLWORExpr
                           | QuantifiedExpr
                           | TypeswitchExpr
                           | IfExpr
                           | OrExpr 
[33]    FLWORExpr    ::=    (ForClause | LetClause)+ WhereClause? 
                                             OrderByClause? "return" ExprSingle

可以清楚地看到，return 标记（关键字）后面必须跟有单个表达式。

但是，通过删除 div 元素，您拥有：

<body>
    <h1>Nobel prize winners</h1>
    {
     for $subject in
           distinct-values(doc("nobel.xml")//subject)
      let $sn := $subject
        return
            <h2>{$sn}</h2>
                <ul>
                  {for $row in doc("nobel.xml")/nobel/row
                    let $name := $row/winner/text()
                    let $year := $row/yr/text()
                    where $row/subject/text()=$subject
                    order by $year
                       return
                         <li> ({$year} {$name} </li>
                  }
                </ul>
        }
</body>

正如我们可以清楚地看到的，return 关键字后面没有跟随单个表达式，由 XQuery 1.0 语法定义。

解决方案：明确指定 return 关键字后面的元素序列，作为序列：

<body>
    <h1>Nobel prize winners</h1>
    {
     for $subject in
           distinct-values(doc("nobel.xml")//subject)
      let $sn := $subject
        return
          (
            <h2>{$sn}</h2>,
                <ul>
                  {for $row in doc("nobel.xml")/nobel/row
                    let $name := $row/winner/text()
                    let $year := $row/yr/text()
                    where $row/subject/text()=$subject
                    order by $year
                       return
                         <li> ({$year} {$name} </li>
                  }
                </ul>
          )
        }
</body>

注意，return后面的元素序列 现在被括号包围，并且序列中的元素由逗号分隔。

现在，当上面的 XQuery 代码在此 nobel.xml 文件上执行时：

<nobel>
 <row>
  <subject>Lit</subject>
  <winner>Solzhenitsin</winner>
  <yr>1969</yr>
 </row>
</nobel>

生成所需的正确结果：

<body>
    <h1>Nobel prize winners</h1>
    <h2>Lit</h2>
    <ul>
        <li> (1969Solzhenitsin</li>
    </ul>
</body>

Here are the syntax rule for the grammar of XQuery 1.0 , as taken from the XQuery 1.0 w3c spec.:

[31]    Expr          ::=    ExprSingle ("," ExprSingle)* 
[32]    ExprSingle    ::=    FLWORExpr
                           | QuantifiedExpr
                           | TypeswitchExpr
                           | IfExpr
                           | OrExpr 
[33]    FLWORExpr    ::=    (ForClause | LetClause)+ WhereClause? 
                                             OrderByClause? "return" ExprSingle

As can be clearly seen, the return token (keyword) must be followed by a single expression.

However, by getting rid of the div element you have:

<body>
    <h1>Nobel prize winners</h1>
    {
     for $subject in
           distinct-values(doc("nobel.xml")//subject)
      let $sn := $subject
        return
            <h2>{$sn}</h2>
                <ul>
                  {for $row in doc("nobel.xml")/nobel/row
                    let $name := $row/winner/text()
                    let $year := $row/yr/text()
                    where $row/subject/text()=$subject
                    order by $year
                       return
                         <li> ({$year} {$name} </li>
                  }
                </ul>
        }
</body>

As we can clearly see, the return keyword is not followed by a single expression, as defined by the XQuery 1.0 grammar.

Solution: Clearly specify the sequence of elements that follow the return keyword, as a sequence:

<body>
    <h1>Nobel prize winners</h1>
    {
     for $subject in
           distinct-values(doc("nobel.xml")//subject)
      let $sn := $subject
        return
          (
            <h2>{$sn}</h2>,
                <ul>
                  {for $row in doc("nobel.xml")/nobel/row
                    let $name := $row/winner/text()
                    let $year := $row/yr/text()
                    where $row/subject/text()=$subject
                    order by $year
                       return
                         <li> ({$year} {$name} </li>
                  }
                </ul>
          )
        }
</body>

Notice that the sequence of elements following return is now surrounded by brackets, and that the elements in the sequence are delimited by a comma.

Now, when the above XQuery code is executed on this nobel.xml file:

<nobel>
 <row>
  <subject>Lit</subject>
  <winner>Solzhenitsin</winner>
  <yr>1969</yr>
 </row>
</nobel>

the wanted, correct result is produced:

<body>
    <h1>Nobel prize winners</h1>
    <h2>Lit</h2>
    <ul>
        <li> (1969Solzhenitsin</li>
    </ul>
</body>

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返回多元素 HTML 作为 xquery 结果

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