xpath choose first table

Question

I have xpath

page.search("//table[@class='campaign']//table")

which returns two tables.

I need to choose only first table. This line doesn't work:

page.search("//table[@class='campaign']//table[1]")

How to choose only first table?

Answer 1

This bugged me, too. I still don't exactly know why your solution does not work. However, this should:

page.search("//table[@class='campaign']/descendant::table[1]")

EDIT: As the docs say,

"The location path //para[1] does not mean the same as the location path /descendant::para[1]. The latter selects the first descendant para element; the former selects all descendant para elements that are the first para children of their parents."

Thanks to your question, I finally understood why this works this way :). So, depending on your structure and needs, this should work.

Answer 2

Instead of using an XPath expression to select the first matching element, you can either find all of them and then pare it down:

first_table = page.search("//table[@class='campaign']//table").first

...or better yet, select only the first by using at:

first_table = page.at("//table[@class='campaign']//table")

Note also that your expression can be found more simply by using the CSS selector syntax:

first_table = page.at("table.campaign table")