的Perl和XPath：考慮層次

Question

我想提取XML的屬性值考慮層級：

<?xml version="1.0" encoding="UTF-8"?> 
<database> 
    <row1s> 
    <row1 name="fox" category="mammal"> 
     <row2s> 
     <row2 type="1"/> 
     <row2 type="2"/> 
     </row2s> 
    </row1> 
    <row1 name="horse" category="mammal"> 
     <row2s> 
     <row2 type="3"/> 
     </row2s> 
    </row1> 
    <row1 name="bee" category="insect"> 
     <row2s/> 
    </row1> 
    <row1 name="wasp" category="insect"> 
     <row2s/> 
    </row1> 
    </row1s> 
</database> 

這是Perl代碼我提取值：

use strict; 
use DBI; 
use XML::XPath; 
use XML::XPath::XMLParser; 

my $xrow1; 
my $xrow2; 

my $xp = XML::XPath->new (filename => "animals3.xml"); 

my $node_list1 = $xp->find ("//row1s/row1"); 

foreach my $row1 ($node_list1->get_nodelist()) { 
    $xrow1 = $row1->getAttribute("name"); 
    print "Level row1 gives: $xrow1\n"; 

    my $node_list2 = $xp->find ("//row2s/row2"); 

    foreach my $row2 ($node_list2->get_nodelist()) { 
    $xrow2 = $row2->getAttribute("type");  
    print "Level row2 gives: $xrow2\n"; 
    } 
} 

我得到的是：

Level row1 gives: fox 
Level row2 gives: 1 
Level row2 gives: 2 
Level row2 gives: 3 
Level row1 gives: horse 
Level row2 gives: 1 
Level row2 gives: 2 
Level row2 gives: 3 
Level row1 gives: bee 
Level row2 gives: 1 
Level row2 gives: 2 
Level row2 gives: 3 
Level row1 gives: wasp 
Level row2 gives: 1 
Level row2 gives: 2 
Level row2 gives: 3 

對於每個級別1，我從級別2獲得所有屬性值。這不是什麼iw螞蟻。我想只輸出correpondent級別1的水平2項，但我要的是：

Level row1 gives: fox 
Level row2 gives: 1 
Level row2 gives: 2 
Level row1 gives: horse 
Level row2 gives: 3 
Level row1 gives: bee 
Level row1 gives: wasp 

我將不勝感激任何提示如何解決這個問題。

謝謝。

Answer 1

領先/表示絕對路徑。

my $node2 = $xp->find("//row2s/row2"); 

應該

my $node2 = $xp->find("row2s/row2", $row1); 

---

評論：

• 無論$node1也不$node2是節點。選擇更好的名字。

• 聲明你所做的變量部分無視聲明它們的目的。他們應該在適當的循環中聲明。

Answer 2

下修復和簡化你的腳本：

use strict; 
use warnings; 

use XML::XPath; 
use XML::XPath::XMLParser; 

#my $xp = XML::XPath->new(filename => "animals3.xml"); 
my $xp = XML::XPath->new(ioref => \*DATA); 

for my $row1 ($xp->findnodes('//row1s/row1')){ 
    printf "Level row1 gives: %s\n", $row1->getAttribute("name"); 

    for my $row2 ($row1->findnodes('.//row2s/row2')) { 
     printf "Level row2 gives: %s\n", $row2->getAttribute("type"); 
    } 
} 

__DATA__ 
<?xml version="1.0" encoding="UTF-8"?> 
<database> 
    <row1s> 
    <row1 name="fox" category="mammal"> 
     <row2s> 
     <row2 type="1"/> 
     <row2 type="2"/> 
     </row2s> 
    </row1> 
    <row1 name="horse" category="mammal"> 
     <row2s> 
     <row2 type="3"/> 
     </row2s> 
    </row1> 
    <row1 name="bee" category="insect"> 
     <row2s/> 
    </row1> 
    <row1 name="wasp" category="insect"> 
     <row2s/> 
    </row1> 
    </row1s> 
</database> 

輸出：

Level row1 gives: fox 
Level row2 gives: 1 
Level row2 gives: 2 
Level row1 gives: horse 
Level row2 gives: 3 
Level row1 gives: bee 
Level row1 gives: wasp