I am using RUBY to screen scrap a web page (created in asp.net) which uses gridview to display data. I am successfully able to read the data displayed on page-1 of the grid but unable to figure out how I can move to the next page in the grid to read all the data.
Problem is the page number hyperlinks are not normal hyperlinks (with URL) but instead are javascript hyperlink which causes postback to the same page..
An example of the hyperlink:-
6
I recommend using Watir, a ruby library designed for browser testing, if you're already using ruby for processing. For one thing, it gives you a much nicer interface to the DOM elements on the page, and it makes clicking links like this easier:
ie.link(:text, '6').click
Then, of course you have easier methods for navigating the table as well. It's easy enough to automate this process:
1..total_number_of_pages.each do |next_page|
ie.link(:text, next_page).click
# table processing goes here
end
I don't know your use case, but this approach has its advantages and disadvantages. For one thing, it actually runs a browser instance, so if this is something you need to frequently run quietly in the background in completely automated way, this may not be the best approach. On the other hand, if it's ok to launch a browser instance, then you don't have to worry about all that postback nonsense, and you can just click the link as if you were a user.
Watir: http://wtr.rubyforge.org/
You'll need to figure out the actual URL.
Option 1a: Open the page in a browser with good developer support (e.g. firefox with the web development tools) and look through the source to find where _doPostBack is defined. Figure out what URL it's constructing. Note that it might not be in the main page source, but instead in something that the page loads.
Option 1b: Ditto, but have ruby do it. If you're fetching the page with Net:HTTP you've got the tools to find the definition of __doPostBack already (the body as a string, ruby's grep, and the ability to request additional files, such as those in script tags).
Option 2: Monitor the traffic between a browser and the page (e.g. with a logging proxy) to find out what the URL is.
Option 3: Ask the owner of the web page.
Option 4: Guess. This may not be as bad as it sounds (e.g. if the original URL ends with "...?page=1" or something) but in general this is the least likely to work.
Edit (in response to your comment on the other question):
Assuming you're using the Net:HTTP library, you can do a postback by just replacing your get with a post, e.g. my_http.post(my_url) instead of my_http.get(my_url)
Edit (in response to danieltalsky's answer):
watir may be a really good solution for you (I'm kicking myself for not having thought of it), but be aware that you may have to manually fire the event or go through other hoops to get what you want. As a specific gotcha, with any asynchronous fetch like this you need to make sure that the full response has come back before you scrape it; that isn't a problem when you're doing the request inline yourself.
You will have to perform the postback. The data is pass with a form POST back to the server. Like Markus said use something like FireBug or the Developer Tools in IE 8 and fiddler to watch the traffic. But honestly this is a web form using the bloated GridView and you will be in for a fun adventure. ;)
You'll need to do some investigation in order to figure out what HTTP request the javascript execution is performing. I've used the Mozilla browser with the Firebug plugin and also the "Live HTTP Headers" plugin to help determine what is going on. It will likely become clear to you which requests you will need to make in order to traverse to the next page. Make sure you pay attention to any cookies getting set.
I've had really good success using Mechanize for scraping. It wraps all of the HTTP communication, html parsing and searching(using Nokogiri), redirection, and holding onto cookies. But it doesn't know how to execute Javascript, which is why you will need to figure out what http request to perform on your own.
Related
I'm still pretty new to AJAX and javascript, but I'm getting there slowly.
I have a web-based application that relies heavily on mySQL and there are individual user accounts that are accessed and the UI is populated with user specific data.
I'm working on getting rid of a tabbed navigation bar that currently loads new pages because all that changes from page to page is information within one box.
The thing is that box needs to reload info from the database, etc.
I have had great help from users here showing that I need to call the database within the php page that ajax is calling.
OK-so pardon the lengthy intro-what I'm wondering is are there any specific limitations to what ajax can call that I need to know about? IE: someone mentioned that it's best not to call script files and that I should remove scripts from the php page that is being called and keep those in the 'parent' page. Any other things like this I need to keep in mind?
To clarify: I'm not looking to discuss the merits/drawbacks of the technology. I'm wondering about specific coding implementation that I need to be aware of (for example-I didn't until yesterday realize that if even if I had established a mySQL connection on the page, that I would need to re establish that connection in my called page as well...makes perfect sense now).
XMLHttpRequest which powers ajax has a number of limitations. I recommend brushing up on the same origin policy. This is a pivotal rule because it limits where AJAX calls can be made.
First, you can't have Javascript embedded in the HTTP response to an AJAX call. That's a security issue.
No mention of the dynamics of the database, but if the data to be displayed in tabs doesn't have to be real-time, why not cache it server-side?
I find that like any other protocol, Ajax works best in tightly controlled conditions. It wouldn't make much sense for updating nearly the whole page, unless you find that the user experience is improved with an on-page 'loader'. Without going into workarounds, disadvantages will include losing the browser back button / history, issues such as the one your friend mentioned, and also embedded resources and other rich content can suffer as well, and just having an extra layer of complexity to deal with in your app. Don't treat it as magic sauce for your app - make sure every use delivers specific results that benefit your client / audience.
IMHO, it's best to put your client side javascript in a separate page and then import it - neater container. one thing I've faced before is how to call xml back which contains code to run such as more javascript - it's worth checking if this is likely earlier on and avoiding, than having to look at evals.
Mildly interesting.
It's not that I'm not familiar with the concept but I'm wondering about what is the best approach when you are creating applications supporting ajax userexperience.
I mostly use ajax with jQuery but also when I want to load information without a pagerefresh. As you will probably know, the XmlHttp Object and the ResponseText provides a nice and easy way to execute a script in the back and display the results e.g. a div.
A bit of a downside of this approach is that its hard to see the actual generated sourcecode. I often take a look at the sourcecode to see if the expected parameters are correctly provided to e.g. formelements.
So I'm curious, what is your approach for creating ajax-data-load functionality? Is it just by the ResponseText property?
Having manually crafted XmlHttpRequest objects for a while, I now use jQuery for all my AJAX-ified stuff. It gives you much better control while coding less.
If you use Firefox, get yourself the Web Developer Toolbar. It has a cool feature called "view generated source code" which generates the HTML code that the browser knows about in the current document as it stands, so it includes the HTML sent back by your AJAX requests.
Also I make it a rule to always tell the user you're loading something rather than relying on the browser to tell them (like Gmail's "Loading" text in the corner for instance.)
I'm trying to log in to a website and save an HTML page automatically (I want to be able to do this on a regular time interval). From the surface, this is a typical modern website where, if the user navigates directly to a "locked" URL, a log-in form pops up, and after logging in, the user is redirected to the intended page.
I gave mechanize a shot (http://wwwsearch.sourceforge.net/mechanize/) but it wasn't finding some form elements which were needed for login (hidden elements that have some values put in by a javascript function that runs when the user clicks the "log in" button).
I played a bit with the "web browser" control in .NET but quickly lost interest because I couldn't even get it to submit a query on the Google page.
I don't care what the language is; I'll learn it to solve this problem. At a minimum it has to work in Windows.
A simple example, say, typing in a query into the Google search box would be a great bonus.
In my experience, the most reliable way is to use javascript. It works well in .Net. To test, browse to the following addresses one after another in Firefox or Internet Explorer:
http://www.google.com
javascript:function f(){document.forms[0]['q'].value='stackoverflow';}f();
javascript:document.forms[0].submit()
That performs a search for "stackoverflow" on Google. To do it in VB .Net using the webbrowser control, do this:
WebBrowser1.Navigate("http://www.google.com")
Do While WebBrowser1.IsBusy OrElse WebBrowser1.ReadyState <> WebBrowserReadyState.Complete
Threading.Thread.Sleep(1000)
Application.DoEvents()
Loop
WebBrowser1.Navigate("javascript:function%20f(){document.forms[0]['q'].value='stackoverflow';}f();")
Threading.Thread.Sleep(2000) 'wait for javascript to run
WebBrowser1.Navigate("javascript:document.forms[0].submit()")
Threading.Thread.Sleep(2000) 'wait for javascript to run
Notice how the space in the URL is converted to %20. I'm not certain if this is necessary but it can't hurt. It is important that the first javascript be in a function. The calls to Sleep() are to wait for Google to load and also for the javascript stuff. The Do While Loop might run forever if the page fails to load so for automation purposes have a counter that will timeout after, say, 60 seconds.
Of course, for Google you can just navigate directly to www.google.com?q=stackoverflow but if your site has hidden input fields, etc, then this is the way to go. Only works for HTML sites - flash is a whole other matter.
If I understand you right, you want to log in to only one webpage, and that form always stays the same. You could either reverse engineer the java script, or debug it via a javascript debugger in the browser (e.g. firebug for firefox). Or you can fill in the form in your browser and look at the http request via a network packet sniffer. Once you have all required form data to submit, you can do the same with your program (thats what I did the last time I had a pretty similar task to do). dont forget to store all cookie data you requested back from the webserver and send it with the next request, to 'stay logged in'.
Its being already discussed here.
Basically its gist is you can use selenium, an open source web automation tool, which has api library available in various languages like java, ruby, etc.
Neoload can handle the form filling with authentication, assuming you don't want to collect data, just perform actions. It's a web stress tool, so it's not really meant to be used as a time-based service, but you COULD just leave it running.
I've used Ruby and Watir (a web app testing suite) for something similar, but it was a very small task (basically visiting URLs from a text file and downloading an image).
There's also an extension called iMacros that can do some automation, but I'm not personally familiar with it (just aware of it).
"I'm trying to log in to a website and save an HTML page automatically"
SAVEAS TYPE=HTM FOLDER=C: FILE=page.html
https://addons.mozilla.org/en-US/firefox/addon/imacros-for-firefox/?src=search
This commands played in iMacros addon will save the page on C: drive and name it page.html
Also,
URL GOTO=www.website.com
Goes on the particular website you want to save. You can also use scripting in iMacros and set different websites in macro.
Right now i'm building a firefox plugin that duplicates some functionality on my website. It takes in an email address and then returns information to the user. The easiest way to do this in the plugin is to use an Iframe and render that super simple form on my website. All of this works great, but to make the plugin really useful, i would like the plugin to have access to the information that the iframe renders, so it can use it in the current window that the user is in.
Is it possible to pass information back through an Iframe in this manner? I know there are quite a few domain access restrictions with Iframes, so any help or insight is appreciated!!
I've done this two ways.
If the iframe is on the same domain as the parent website, you can just, in javascript, access window.parent.
If it isn't, however...I've done a dirty trick. I'll share it here, though, as it may help.
We created a page on the other domain, which would call to window.parent.parent. We put that in a hidden iframe inside the iframed page, and send it a querystring argument or two. It's not pretty, but it gets around cross-domain scripting problems.
This basically means that you have this sort of thing:
admin.example.com
content.example.com - iframe
admin.example.com?contentid=350 - hidden iframe that makes a window.parent.parent call.
Is the point of this whole exercise functional testing of your website? If so, instead of your custom Firefox plugin, consider using Selenium to automate interactions with websites. It works with all major browsers and supports the inspection of page elements you are trying to do (using XPath). It also features a Firefox plugin called Selenium IDE that allows you to conveniently "record" your interactions with a website for automated playback later.
I have a web site which I download 2-3 MB of raw data from that then feeds into an ETL process to load it into my data mart. Unfortunately the data provider is the US Dept. of Ag (USDA) and they do not allow downloading via FTP. They require that I use a web form to select the elements I want, click through 2-3 screens and eventually click to download the file. I'd like to automate this download process. I am not a web developer but somehow it seems that I should be able to use some tool to tell me exactly what put/get/magic goes from the final request to the server. If I had a tool that said, "pass these parameters to this url and wait for a response" I could then hack something together in Perl to automate this process.
I realize that if I deconstructed all 5 of their pages and read through the JavaScript includes and tapped my heals together 3 times I could get this info from what I have access to. But I want a faster and more direct path that does not require me to manually parse all their JS.
Restatement of the final question: Is there a tool or method that will show clearly what the final request request sent from a web form was and how it was structured?
A tamperer's best friends (these are firefox extensions, you could also use something like Wireshark)
HTTPFox
Tamper Data
Best of luck
Use Fiddler2 as a proxy to see what is being passed back and forth. I've done this with success in other similar circumstances
Home page is here: http://www.fiddler2.com/fiddler2/
As with the other responses, except my tool of choice is Charles
What about using a web testing toolkit, like Watir and Ruby ?
Easy to fill in the forms.. just use the output..
Use WatiN and combine it with WatiN TestRecorder (Google for it)
It can "simulate" a user sitting in front of the browser punching in values which you can supply from your own C# code...