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#*******************************************************************************

#* Loop to collect more game reviews

#*

#*******************************************************************************

#*

# clear workspace

rm(list = ls())

# load necessary packages

library(httr)

library(jsonlite)

library(lubridate)

# gameid of Dota 2 - you can change it!

gameid = 570

# Number of requests

n = 100

# create an empty data frame

game.rev <- data.frame() 

# establish the base path URL

rev.url1 = "https://store.steampowered.com/appreviews/"

# establish the URL extension

rev.url2 = "?json=1&filter=recent&num_per_page=100&cursor="

for (i in 1:n) {

  # create a conditional statement to assign initial query cursor to cursor=* only for i == 1

  if(i == 1){cursor = "*"} 

  # run the API query for batch i.

  rev.request <- GET(url = paste0(rev.url1, gameid, rev.url2, cursor))

  # convert query from Unicode to a string, save as tibble.

  reviews.raw <- content(rev.request, as = "text", encoding = "UTF-8")

  reviews.list <- fromJSON(reviews.raw)

  reviews <- reviews.list$reviews

  # unnest data frame

  reviews <- do.call("data.frame", reviews)

  # # Having issues with 100 reviews per page. Running out of pages and function is aborting.

  # # Must design if/else statement to check if 'recommendationid' exists. If TRUE, continue with loop,

  # # If false, then break.

  if (('recommendationid' %in% names(reviews)) == TRUE) {

  reviews$recommendationid <- as.character(reviews$recommendationid)

  reviews$weighted_vote_score     <- as.numeric(reviews$weighted_vote_score)

  # convert Unix timestamp to date.time format.

  reviews$timestamp_created  <- as_datetime(reviews$timestamp_created)

  reviews$timestamp_updated  <- as_datetime(reviews$timestamp_updated)

  reviews$author.last_played <- as_datetime(reviews$author.last_played)

  # to request the next n reviews, need to extract a custom cursor that is provided within the previous request

  cursor <- fromJSON(content(rev.request, as = "text", encoding = "UTF-8"))$cursor

  # some cursors return characters that are not URL encoded. 

  # Must replace problem pagination "+" with correct character "%2B.

  cursor <- gsub('\\+','%2B', cursor)

  # check if the number of columns are the same

  if(i > 1 & ncol(game.rev) != ncol(reviews)){vars <- intersect(names(reviews),names(game.rev))

  game.rev <- game.rev[,names(game.rev)%in% vars]

  reviews <-reviews[,names(reviews)%in% vars]

  }

  game.rev <- rbind(game.rev, reviews)

  # if recommendationid does not exist in the data frame, then break.

  }else {

    print(paste0("No further recent reviews are available for App ID #",

                 as.character(gameid), ". Query ", as.character(i), " of ",

                 as.character(n), " aborted. No further queries possible."))

    break}

  # Printing status code.

  message(".", appendLF = FALSE) 

  Sys.sleep(time = 0.5)

  message(".", appendLF = FALSE) 

  Sys.sleep(time = 0.5)

  message(".", appendLF = FALSE) 

  Sys.sleep(time = 0.5)

}