Ruby Net::HTTP::Post 提交表单

Question

我正在创建一个网站抓取工具。有一个表格用来改变当前页面。

这是我为 POST 请求提交表单的方式，但它似乎一遍又一遍地获取相同的页面。

这里是一些示例代码：

pages = {
 "total_pages" => 19,
 "p1" => '1234/1456/78990/123324345/12143343214345/231432143/12432412/435435/',
 "p2" => '1432424/123421421/345/435/6/65/5/34/3/2/21/1243',
..
..
..    
}


idx = 1
p_count = pages["total_pages"]

#set up the HTTP request to change pages to get all the auction results
uri = URI.parse("http://somerandomwebsite.com?listings")
http = Net::HTTP.new(uri.host, uri.port)
req = Net::HTTP::Post.new(uri.request_uri)

p_count.times do
  puts "On loop sequence: #{idx}"
  pg_num = "p#{idx}"
  pg_content = pages["#{pg_num}"]
  req.set_form_data({"page" => "#{pg_num}", "#{pg_num}" => "#{pg_content}"})

  response = http.request(req)
  page = Nokogiri::HTML(response.body)
  idx = idx + 1
end

看起来page 永远不会改变。每次我希望确保正确的参数被传递时，有没有办法查看完整请求的样子？似乎几乎不可能确定有关req 的任何信息。

Answer 1

调试 HTTP 的一个好方法是利用 http://httpbin.org：

require 'net/http'
uri = URI('http://httpbin.org/post')
res = Net::HTTP.post_form(uri, 'q' => 'ruby', 'max' => '50')
puts res.body

返回：

# >> {
# >>   "args": {}, 
# >>   "data": "", 
# >>   "files": {}, 
# >>   "form": {
# >>     "max": "50", 
# >>     "q": "ruby"
# >>   }, 
# >>   "headers": {
# >>     "Accept": "*/*", 
# >>     "Accept-Encoding": "gzip;q=1.0,deflate;q=0.6,identity;q=0.3", 
# >>     "Content-Length": "13", 
# >>     "Content-Type": "application/x-www-form-urlencoded", 
# >>     "Host": "httpbin.org", 
# >>     "User-Agent": "Ruby"
# >>   }, 
# >>   "json": null, 
# >>   "origin": "216.69.191.1", 
# >>   "url": "http://httpbin.org/post"
# >> }

也就是说，我建议不要使用 Net::HTTP。 Ruby 有很多很棒的 HTTP 客户端，它们可以让您更轻松地编写代码。例如，这里使用HTTPClient：

require 'httpclient'
clnt = HTTPClient.new
res = clnt.post('http://httpbin.org/post', 'q' => 'ruby', 'max' => '50')
puts res.body

# >> {
# >>   "args": {}, 
# >>   "data": "", 
# >>   "files": {}, 
# >>   "form": {
# >>     "max": "50", 
# >>     "q": "ruby"
# >>   }, 
# >>   "headers": {
# >>     "Accept": "*/*", 
# >>     "Content-Length": "13", 
# >>     "Content-Type": "application/x-www-form-urlencoded", 
# >>     "Date": "Thu, 09 Feb 2017 20:03:57 GMT", 
# >>     "Host": "httpbin.org", 
# >>     "User-Agent": "HTTPClient/1.0 (2.8.3, ruby 2.4.0 (2016-12-24))"
# >>   }, 
# >>   "json": null, 
# >>   "origin": "216.69.191.1", 
# >>   "url": "http://httpbin.org/post"
# >> }

这是未经测试的代码，因为你没有告诉我们足够多，但这是我开始做你正在做的事情的地方：

require 'httpclient'

BASE_URL = 'http://somerandomwebsite.com?listings'
PAGES = [
 '1234/1456/78990/123324345/12143343214345/231432143/12432412/435435/',
 '1432424/123421421/345/435/6/65/5/34/3/2/21/1243',
]

clnt = HTTPClient.new

PAGES.each.with_index(1) do |page, idx|
  puts "On loop sequence: #{idx}"

  response = clnt.post(BASE_URL, 'page' => idx, idx => page)

  doc = Nokogiri::HTML(response.body)
  # ...
end