First I'd like to take a moment and thank the SO community, You helped me many times in the past without me needing to even create an account.
My current problem involves web scraping with R. Not my strong point.
I would like to scrap http://www.cbs.dtu.dk/services/SignalP/
what I have tried:
library(rvest)
url <- "http://www.cbs.dtu.dk/services/SignalP/"
seq <- "MTSKTCLVFFFSSLILTNFALAQDRAPHGLAYETPVAFSPSAFDFFHTQPENPDPTFNPCSESGCSPLPVAAKVQGASAKAQESDIVSISTGTRSGIEEHGVVGIIFGLAFAVMM"
session <- rvest::html_session(url)
form <- rvest::html_form(session)[[2]]
form <- rvest::set_values(form, `SEQPASTE` = seq)
form_res_cbs <- rvest::submit_form(session, form)
#rvest prints out:
Submitting with 'trunc'
rvest::html_text(rvest::html_nodes(form_res_cbs, "head"))
#ouput:
"Configuration error"
rvest::html_text(rvest::html_nodes(form_res_cbs, "body"))
#ouput:
"Exception:WebfaceConfigErrorPackage:Webface::service : 358Message:Unhandled #parameter 'NULL' in form "
I am unsure what is the unhandled parameter. Is the problem in the submit button? I can not seem to force:
form_res_cbs <- rvest::submit_form(session, form, submit = "submit")
#rvest prints out
Error: Unknown submission name 'submit'.
Possible values: trunc
is the problem the submit$name is NULL?
form[["fields"]][[23]]
I tried defining the fake submit button as suggested here: Submit form with no submit button in rvest
with no luck.
I am open to solutions using rvest or RCurl/httr, I would like to avoid using RSelenium
EDIT: thanks to hrbrmstr awesome answer I was able to build a function for this task. It is available in the package ragp: https://github.com/missuse/ragp