如何在 Xpath 节点集内使用 Selenium 按索引选择指定的节点？

我在写一个硒的测试案例。下面是我用来匹配数据表中所有“修改”按钮的 xpath 表达式。

//img[@title='Modify']

我的问题是，如何通过索引访问匹配的节点集

//img[@title='Modify'][i]

还有

//img[@title='Modify' and position() = i]

但都不管用。 I also tried with XPath checker(One firefox extension). There're totally 13 matches found, then I have totally no idea how am I gonna select one of them.. 还是 XPath 支持指定的不在同一父节点下的节点选择？

190914 次浏览
小开

There is no i in XPath.

Either you use literal numbers: //img[@title='Modify'][1]

Or you build the expression string dynamically: '//img[@title='Modify']['+i+']' (but keep in mind that dynamic XPath expressions do not work from within XSLT).

Or does XPath support specified selection of nodes which are not under same parent node?

Yes: (//img[@title='Modify'])[13]

This //img[@title='Modify'][i] means "any <img> with a title of 'Modify' and a child element named <i>."

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//img[@title='Modify'][i]

is short for

/descendant-or-self::node()/img[@title='Modify'][i]

hence is returning the i'th node under the same parent node.

You want

/descendant-or-self::img[@title='Modify'][i]
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最佳答案

This is a FAQ:

//someName[3]

means: all someName elements in the document, that are the third someName child of their parent -- there may be many such elements.

What you want is exactly the 3rd someName element:

(//someName)[3]

Explanation: the [] has a higher precedence (priority) than //. Remember always to put expressions of the type //someName in brackets when you need to specify the Nth node of their selected node-list.

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(//*[@attribute='value'])[index] to find target of element while your finding multiple matches in it

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There is no i in xpath is not entirely true. You can still use the count() to find the index.

Consider the following page

<html>


<head>
<title>HTML Sample table</title>
</head>


<style>
table, td, th {
border: 1px solid black;
font-size: 15px;
font-family: Trebuchet MS, sans-serif;
}
table {
border-collapse: collapse;
width: 100%;
}


th, td {
text-align: left;
padding: 8px;
}


tr:nth-child(even){background-color: #f2f2f2}


th {
background-color: #4CAF50;
color: white;
}
</style>


<body>
<table>
<thead>
<tr>
<th>Heading 1</th>
<th>Heading 2</th>
<th>Heading 3</th>
<th>Heading 4</th>
<th>Heading 5</th>
<th>Heading 6</th>
</tr>
</thead>
<tbody>
<tr>
<td>Data row 1 col 1</td>
<td>Data row 1 col 2</td>
<td>Data row 1 col 3</td>
<td>Data row 1 col 4</td>
<td>Data row 1 col 5</td>
<td>Data row 1 col 6</td>
</tr>
<tr>
<td>Data row 2 col 1</td>
<td>Data row 2 col 2</td>
<td>Data row 2 col 3</td>
<td>Data row 2 col 4</td>
<td>Data row 2 col 5</td>
<td>Data row 2 col 6</td>
</tr>
<tr>
<td>Data row 3 col 1</td>
<td>Data row 3 col 2</td>
<td>Data row 3 col 3</td>
<td>Data row 3 col 4</td>
<td>Data row 3 col 5</td>
<td>Data row 3 col 6</td>
</tr>
<tr>
<td>Data row 4 col 1</td>
<td>Data row 4 col 2</td>
<td>Data row 4 col 3</td>
<td>Data row 4 col 4</td>
<td>Data row 4 col 5</td>
<td>Data row 4 col 6</td>
</tr>
<tr>
<td>Data row 5 col 1</td>
<td>Data row 5 col 2</td>
<td>Data row 5 col 3</td>
<td>Data row 5 col 4</td>
<td>Data row 5 col 5</td>
<td>Data row 5 col 6</td>
</tr>
<tr>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
</tr>
</tbody>
</table>


</br>


<table>
<thead>
<tr>
<th>Heading 7</th>
<th>Heading 8</th>
<th>Heading 9</th>
<th>Heading 10</th>
<th>Heading 11</th>
<th>Heading 12</th>
</tr>
</thead>
<tbody>
<tr>
<td>Data row 1 col 1</td>
<td>Data row 1 col 2</td>
<td>Data row 1 col 3</td>
<td>Data row 1 col 4</td>
<td>Data row 1 col 5</td>
<td>Data row 1 col 6</td>
</tr>
<tr>
<td>Data row 2 col 1</td>
<td>Data row 2 col 2</td>
<td>Data row 2 col 3</td>
<td>Data row 2 col 4</td>
<td>Data row 2 col 5</td>
<td>Data row 2 col 6</td>
</tr>
<tr>
<td>Data row 3 col 1</td>
<td>Data row 3 col 2</td>
<td>Data row 3 col 3</td>
<td>Data row 3 col 4</td>
<td>Data row 3 col 5</td>
<td>Data row 3 col 6</td>
</tr>
<tr>
<td>Data row 4 col 1</td>
<td>Data row 4 col 2</td>
<td>Data row 4 col 3</td>
<td>Data row 4 col 4</td>
<td>Data row 4 col 5</td>
<td>Data row 4 col 6</td>
</tr>
<tr>
<td>Data row 5 col 1</td>
<td>Data row 5 col 2</td>
<td>Data row 5 col 3</td>
<td>Data row 5 col 4</td>
<td>Data row 5 col 5</td>
<td>Data row 5 col 6</td>
</tr>
<tr>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
<td><button>Modify</button></td>
</tr>
</tbody>
</table>


</body>
</html>

The page has 2 tables and has 6 columns each with unique column names and 6 rows with variable data. The last row has the Modify button in both the tables.

Assuming that the user has to select the 4th Modify button from the first table based on the heading

Use the xpath //th[.='Heading 4']/ancestor::thead/following-sibling::tbody/tr/td[count(//tr/th[.='Heading 4']/preceding-sibling::th)+1]/button

The count() operator comes in handy in situations like these.

Logic:

  1. Find the header for the Modify button using //th[.='Heading 4']
  2. Find the index of the header column using count(//tr/th[.='Heading 4']/preceding-sibling::th)+1

Note: Index starts at 0

  1. Get the rows for the corresponding header using //th[.='Heading 4']/ancestor::thead/following-sibling::tbody/tr/td[count(//tr/th[.='Heading 4']/preceding-sibling::th)+1]

  2. Get the Modify button from the extracted node list using //th[.='Heading 4']/ancestor::thead/following-sibling::tbody/tr/td[count(//tr/th[.='Heading 4']/preceding-sibling::th)+1]/button

小开

Here is the solution for index variable

Let's say, you have found 5 elements with same locator and you would like to perform action on each element by providing index number (here, variable is used for index as "i")

for(int i=1; i<=5; i++)
{
string xPathWithVariable = "(//div[@class='className'])" + "[" + i + "]";
driver.FindElement(By.XPath(xPathWithVariable)).Click();
}

It takes XPath :

(//div[@class='className'])[1]
(//div[@class='className'])[2]
(//div[@class='className'])[3]
(//div[@class='className'])[4]
(//div[@class='className'])[5]

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