Understanding Selectors

Let’s start by Understanding Selectors. A simple selector is either a type selector or universal selector followed immediately by zero or more attribute selectors, ID selectors, or pseudo-classes, in any order. Moreover, it matches only if all of its components match. Therefore, a selector is a chain of one or more simple selectors separated by combinators. Not to mention, combinators are white space, “>”, and “+”. However, white space may appear between a combinator and the simple selectors around it.

In the same vein, the elements of the document tree that match a selector are called subjects of the selector. Moreover, a selector consists of a single simple selector matches any element satisfying its requirements. Further, prepending a simple selector and combinator to a chain imposes additional matching constraints, so the subjects of a selector are always a subset of the elements matching the last simple selector.

Selectors

Certainly, Capybara does not try to guess what kind of selector you are going to give it, and will always use CSS by default. If you want to use XPath, you’ll need to do:

within(:xpath, ‘//ul/li’) { … }

find(:xpath, ‘//ul/li’).text

find(:xpath, ‘//li[contains(.//a[@href = “#”]/text(), “foo”)]’).value

Alternatively you can set the default selector to XPath:

Capybara.default_selector = :xpath

find(‘//ul/li’).text

Moreover, Capybara allows you to add custom selectors, which can be very useful if you find yourself using the same kinds of selectors very often:

Capybara.add_selector(:id) do

xpath { |id| XPath.descendant[XPath.attr(:id) == id.to_s] }

end

 

Capybara.add_selector(:row) do

xpath { |num| “.//tbody/tr[#{num}]” }

end

 

Capybara.add_selector(:flash_type) do

css { |type| “#flash.#{type}” }

end

So, The block given to xpath must always return an XPath expression as a String, or an XPath expression generated through the XPath gem. Moreover, you can now use these selectors like this:

find(:id, ‘post_123’)

find(:row, 3)

find(:flash_type, :notice)

The above example clearly explains working with windows. We hope this is section is now clear to you. But, in case you need more assistance, we’re always here to help. So, try the links below for further assistance.

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