r - 在 R 中使用 rvest 填充和提交搜索

Question

我正在学习如何填写表格和提交 rvest在 R 中，当我想在 stackoverflow 中搜索 ggplot 标签时，我陷入了困境。这是我的代码:

url<-"https://stackoverflow.com/questions"

(session<-html_session("https://stackoverflow.com/questions"))

(form<-html_form(session)[[2]])
(filled_form<-set_values(form, tagQuery = "ggplot"))
searched<-submit_form(session, filled_form)

我有错误:

Submitting with '<unnamed>'
Error in parse_url(url) : length(url) == 1 is not TRUE

按照这个问题( rvest error on form submission )我尝试了几件事来解决这个问题，但我不能:

filled_form$fields[[13]]$name<-"submit"
filled_form$fields[[14]]$name<-"submit"
filled_form$fields[[13]]$type<-"button"
filled_form$fields[[14]]$type<-"button"

任何帮助家伙

Answer 1

搜索查询在 html_form(session)[[1]]因为没有 submit这种形式的按钮:

<form> 'search' (GET /search)
  <input text> 'q': 

此 workaround似乎工作:

<form> 'search' (GET /search)
  <input text> 'q': 
  <input submit> '': 

给出以下代码序列:

library(rvest)
url<-"https://stackoverflow.com/questions"
(session<-html_session("https://stackoverflow.com/questions"))
(form<-html_form(session)[[1]])

fake_submit_button <- list(name = NULL,
                           type = "submit",
                           value = NULL,
                           checked = NULL,
                           disabled = NULL,
                           readonly = NULL,
                           required = FALSE)
attr(fake_submit_button, "class") <- "input"

form[["fields"]][["submit"]] <- fake_submit_button
(filled_form<-set_values(form, q = "ggplot"))


searched<-submit_form(session, filled_form)

问题是回复有验证码:

searched$url
[1] "https://stackoverflow.com/nocaptcha?s=7291e7e6-9b8b-4b5f-bd1c-0f6890c23573"

您将无法使用 rvest 处理此问题，但在验证码上手动单击后，您会得到您正在寻找的查询:

https://stackoverflow.com/search?q=ggplot

可能更容易使用我的 other answer和:

read_html(paste0('https://stackoverflow.com/search?tab=newest&q=',search))