使用 BaseX/XQuery 将 XML 转换为 CSV

Question

我正在尝试将大量 xml 转换为单个 csv 文件。 xml 的简化结构如下所示：

<Receipts>
    <Receipt>
        <Field1 attribute1="a"/>
        <Fields2>
            <Field2 attribute2="1"/>
            <Field2 attribute2="2"/>
        </Fields2>
        <Field4 attribute4="4a"/>
    </Receipt>
    <Receipt>
        <Field1 attribute1="b"/>
        <Field4 attribute4="4b"/>
    </Receipt>
    <Receipt>
        <Field1 attribute1="c"/>
        <Fields2>
            <Field2 attribute2="3"/>
        </Fields2>
        <Field3 attribute3="c3"/>
        <Field4 attribute4="4c"/>
    </Receipt>
</Receipts>

而我想要得到的csv结果是

Attribute1,Attribute2,Attribute3,Attribute4
a,1,,4a
a,2,,4a
b,,,4b
c,3,c3,4c

我的代码基于this answer，但我只能在 csv 上为每个收据添加一行，并连接所有属性 2，或者只返回具有 Fields2 元素和 Field2 的收据， 那是： 要么这样：

Attribute1,Attribute2,Attribute3,Attribute4
a,1 2,,4a
b,,,4b
c,3,c3,4c

或者这个：

Attribute1,Attribute2,Attribute3,Attribute4
a,1,,4a
a,2,,4a
c,3,c3,4c

我的第一种情况的代码是：

declare option output:method "csv";
declare option output:csv "header=yes, separator=comma";

    declare context item := document {<Receipts>
    <Receipt>
        <Field1 attribute1="a"/>
        <Fields2>
            <Field2 attribute2="1"/>
            <Field2 attribute2="2"/>
        </Fields2>
        <Field4 attribute4="4a"/>
    </Receipt>
    <Receipt>
        <Field1 attribute1="b"/>
        <Field4 attribute4="4b"/>
    </Receipt>
    <Receipt>
        <Field1 attribute1="c"/>
        <Fields2>
            <Field2 attribute2="3"/>
        </Fields2>
        <Field3 attribute3="c3"/>
        <Field4 attribute4="4c"/>
    </Receipt>
</Receipts>};



for $x in //Receipt
return 
<csv>
  <record>
    <Attribute1>{$x/Field1/@attribute1/data()}</Attribute1>
    <Attribute2>{$x/Fields2/Field2/@attribute2/data()}</Attribute2>
    <Attribute3>{$x/Field3/@attribute3/data()}</Attribute3>
    <Attribute4>{$x/Field4/@attribute4/data()}</Attribute4>
  </record>
</csv>

第二种情况是：

declare option output:method "csv";
declare option output:csv "header=yes, separator=comma";

    declare context item := document {<Receipts>
    <Receipt>
        <Field1 attribute1="a"/>
        <Fields2>
            <Field2 attribute2="1"/>
            <Field2 attribute2="2"/>
        </Fields2>
        <Field4 attribute4="4a"/>
    </Receipt>
    <Receipt>
        <Field1 attribute1="b"/>
        <Field4 attribute4="4b"/>
    </Receipt>
    <Receipt>
        <Field1 attribute1="c"/>
        <Fields2>
            <Field2 attribute2="3"/>
        </Fields2>
        <Field3 attribute3="c3"/>
        <Field4 attribute4="4c"/>
    </Receipt>
</Receipts>};



for $x in //Receipt for $y in $x/Fields2/Field2
return 
<csv>
  <record>
    <Attribute1>{$x/Field1/@attribute1/data()}</Attribute1>
    <Attribute2>{$y/@attribute2/data()}</Attribute2>
    <Attribute3>{$x/Field3/@attribute3/data()}</Attribute3>
    <Attribute4>{$x/Field4/@attribute4/data()}</Attribute4>
  </record>
</csv>

Answer 1

经过更深入的搜索，我找到了解决方案。在第二个 for 循环的第二个选项上，您应该添加 allowing empty 函数，以便代码最终看起来像这样：

declare option output:method "csv";
declare option output:csv "header=yes, separator=comma";

    declare context item := document {<Receipts>
    <Receipt>
        <Field1 attribute1="a"/>
        <Fields2>
            <Field2 attribute2="1"/>
            <Field2 attribute2="2"/>
        </Fields2>
        <Field4 attribute4="4a"/>
    </Receipt>
    <Receipt>
        <Field1 attribute1="b"/>
        <Field4 attribute4="4b"/>
    </Receipt>
    <Receipt>
        <Field1 attribute1="c"/>
        <Fields2>
            <Field2 attribute2="3"/>
        </Fields2>
        <Field3 attribute3="c3"/>
        <Field4 attribute4="4c"/>
    </Receipt>
</Receipts>};



for $x in //Receipt for $y allowing empty in $x/Fields2/Field2
return 
<csv>
  <record>
    <Attribute1>{$x/Field1/@attribute1/data()}</Attribute1>
    <Attribute2>{$y/@attribute2/data()}</Attribute2>
    <Attribute3>{$x/Field3/@attribute3/data()}</Attribute3>
    <Attribute4>{$x/Field4/@attribute4/data()}</Attribute4>
  </record>
</csv>

返回请求者 CSV：

Attribute1,Attribute2,Attribute3,Attribute4
a,1,,4a
a,2,,4a
b,,,4b
c,3,c3,4c