I am creating an R function that takes a station number, navigates the Canada Hydrometric, and downloads all data for this station. I'm encountering a few problems and they may be due to the radio buttons and/or that the search button isn't named. This is what I have:
station_number <- "08NM083"
url <- "https://wateroffice.ec.gc.ca/search/historical_e.html"
user_a <- httr::user_agent("Mozilla/5.0 (Macintosh; Intel Mac OS X 12_0_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36")
my_session <- session(url, user_a)
form <- html_form(my_session)[[2]]
which gives:
<form> 'search-form' (GET https://wateroffice.ec.gc.ca/search/historical_results_e.html)
<field> (submit) : Search
<field> (radio) search_type: station_name
<field> (text) station_name:
<field> (radio) search_type: station_number
<field> (text) station_number:
<field> (radio) search_type: province
<field> (select) province: AB
<field> (radio) search_type: basin
<field> (select) basin:
<field> (radio) search_type: region
<field> (select) region: ATL
<field> (radio) search_type: coordinate
<field> (number) north_degrees:
<field> (number) north_minutes:
<field> (number) north_seconds:
<field> (number) south_degrees:
<field> (number) south_minutes:
<field> (number) south_seconds:
<field> (number) east_degrees:
<field> (number) east_minutes:
<field> (number) east_seconds:
<field> (number) west_degrees:
<field> (number) west_minutes:
<field> (number) west_seconds:
<field> (select) parameter_type: all
<field> (number) start_year: 1850
<field> (number) end_year: 2023
<field> (number) minimum_years:
<field> (checkbox) latest_year: Y
<field> (select) regulation: all
<field> (select) station_status: all
<field> (select) operation_schedule:
<field> (select) contributing_agency: all
<field> (select) gross_drainage_operator: >
<field> (number) gross_drainage_area:
<field> (select) effective_drainage_operator: >
<field> (number) effective_drainage_area:
<field> (select) sediment: ---
<field> (select) real_time: ---
<field> (select) rhbn: ---
<field> (select) contributed: ---
<field> (submit) : Search
When I fill out the form and submit, however, nothing seems to have changed.
filled <- form %>%
html_form_set(station_number = station_number,
search_type = "station_number")
resp <- session_submit(x = my_session, form = filled)
my_session and resp:
> my_session
<session> https://wateroffice.ec.gc.ca/search/historical_e.html
Status: 200
Type: text/html; charset=UTF-8
Size: 45034
> resp
<session> https://wateroffice.ec.gc.ca/search/historical_e.html
Status: 200
Type: text/html; charset=UTF-8
Size: 45284
Any suggestions are welcomed!
kaliiiiiiiii's suggestion of pasting in the station number into the url has worked wonderfully for this part of my problem! I still cannot figure out how to download the csv file.
Current code:
station_number <- "08NM083"
url <- paste0("https://wateroffice.ec.gc.ca/search/historical_results_e.html?search_type=station_number&station_number=",
station_number,
"&start_year=1850&end_year=2023&minimum_years=&gross_drainage_operator=%3E&gross_drainage_area=&effective_drainage_operator=%3E&effective_drainage_area=")
user_a <- httr::user_agent("Mozilla/5.0 (Macintosh; Intel Mac OS X 12_0_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36")
my_session <- session(url, user_a)
form <- html_form(my_session)[[2]]
filled <- form %>%
html_form_set(check_all = "all")
resp <- session_submit(x = my_session, form = filled, submit = "download")
resp
link <- resp %>%
read_html() %>%
html_element("p+ section .col-lg-4:nth-child(1) a") %>%
html_attr("href")
full_link <- url_absolute(link, url)
And my attempts at downloading the file:
download.file(full_link, destfile = "Downloads/test_hydat.csv")
test <- read_csv(full_link)
The two above contain only html code.
Figured it out! I needed to jump to the "download csv" link and specifically pull the new session's response content. Full code below for anyone who needs to do something similar:
station_number <- "08NM083"
url <- paste0("https://wateroffice.ec.gc.ca/search/historical_results_e.html?search_type=station_number&station_number=",
station_number,
"&start_year=1850&end_year=2023&minimum_years=&gross_drainage_operator=%3E&gross_drainage_area=&effective_drainage_operator=%3E&effective_drainage_area=")
user_a <- httr::user_agent("Mozilla/5.0 (Macintosh; Intel Mac OS X 12_0_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.69 Safari/537.36")
my_session <- session(url, user_a)
form <- html_form(my_session)[[2]]
filled <- form %>%
html_form_set(check_all = "all")
resp <- session_submit(x = my_session, form = filled, submit = "download")
link <- resp %>%
read_html() %>%
html_element("p+ section .col-lg-4:nth-child(1) a") %>%
html_attr("href")
full_link <- url_absolute(link, url)
next_ses <- my_session %>%
session_jump_to(full_link)
writeBin(next_ses$response$content, "Downloads/test_hydat.csv")