R/getDataForTag.R

In stephaniereinders/rscrapps: Scrape app information from the Google Play Store

#' getDataForTag
#'
#' Scrape an app page in the Google Play Store for information associated with a specific html tag.
#'
#' @param app_url The url for an app page in the Google Play Store
#' @param html_tag An html tag. E.g. "div"
#' @param html_attribute An html attribute associated with the html tag. E.g. "class"
#' @param html_attribute_value The value associated with the html attribute. E.g. "KmO8jd"
#'
#' @return data
#' @export
#'
#' @import rvest
#' @import xml2
#' @import magrittr
#' @importFrom assertthat assert_that
#'
#' @examples
#' app_url <- "https://play.google.com/store/apps/details?id=com.dinaga.photosecret"
#' getDataForTag(app_url, "div", "class", "KmO8jd")
#' getDataForTag(app_url, "a", "class", "hrTbp R8zArc")
getDataForTag <- function(app_url, html_tag, html_attribute, html_attribute_value) {

  # # Checks
  # assert_that(
  #   # app_url needs to be a character
  #   is.character(app_url),
  #
  #   # app_url must start with the string "https://play.google.com/store/apps/details?id="
  #   startsWith(app_url, "https://play.google.com/store/apps/details?id="),
  #
  #   # html_tag, html_attribute, and html_attribute_value are characters
  #   is.character(html_tag),
  #   is.character(html_attribute),
  #   is.character(html_attribute_value)
  # )

  # Combine html_tag, html_attribute, and html_attribute value into properly formatted search text
  search_text <- paste0("//", html_tag, "[contains(@", html_attribute, ",'", html_attribute_value, "')]")

  # Scrape the app page
  data <- app_url %>%
    read_html() %>%
    html_nodes("body") %>%
    xml2::xml_find_all(search_text) %>%
    html_text()

  return(data)
}