InvalidSelectorException: Message: invalid selector: The result of the xpath expression is [object Attr]. It should be an element using XPath Selenium

This error message...

selenium.common.exceptions.InvalidSelectorException: Message: invalid selector: The result of the xpath expression "//a[following-sibling::input[@value="ST"]]/@href" is: [object Attr]. It should be an element.

......implies that your XPath expression was not a valid xpath expression.

For the record Selenium WebDriver supports xpath-1.0 only which returns the set of node(s) selected by the xpath.

You can find the xpath-1.0 specifications in XML Path Language (XPath) Version 1.0

Where as the xpath expression you have used:

driver.find_element_by_xpath('//a[following-sibling::input[@value="ST"]]/@href')

Is a xpath-2.0 based expression and would typically return an object Attr. A couple of examples:

• //@version: selects all the version attribute nodes that are in the same document as the context node
• ../@lang: selects the lang attribute of the parent of the context node

You can find the xpath-2.0 specifications in XML Path Language (XPath) 2.0 (Second Edition)

Solution

To locate the desired element with a href attribute connected to a student named "John Doe" based on the following-sibling input value of ST you can use either of the following xpath based Locator Strategies:

• Using preceding:

  driver.find_element_by_xpath("//input[@value='ST']//preceding::a[1]").click()
  

• Using preceding-sibling:

  driver.find_element_by_xpath("//input[@value='ST']//preceding-sibling::a[@href]").click()