rvest how to select a specific css node by id

Question

I\'m trying to use the rvest package to scrape data from a web page. In a simple format, the html code looks like this:

   

        
                      

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Answer 1

You can use xpath:

require(rvest)
text <- '<div class="style">
   <input id="a" value="123">
   <input id="b">
</div>'

h <- read_html(text)

h %>% 
  html_nodes(xpath = '//*[@id="a"]') %>%
  xml_attr("value")

The easiest way to get css- and xpath-selector is to use http://selectorgadget.com/. For a specific attribute like yours use chrome's developer toolbar to get the xpath as follows:

Answer 2

This will work just fine with straight CSS selectors:

library(rvest)

doc <- '<div class="style">
   <input id="a" value="123">
   <input id="b">
</div>'

pg <- html(doc)
html_attr(html_nodes(pg, "div > input:first-of-type"), "value")

## [1] "123"

Answer 3

Adding an answer bc I don't see the easy css selector shorthand for selecting by id: using #your_id_name:

h %>% 
  html_node('#a') %>%
  html_attr('value')

which outputs "123" as desired.

Same setup as the others:

require(rvest)
text <- '<div class="style">
   <input id="a" value="123">
   <input id="b">
</div>'

h <- read_html(text)