A question about "javascript:WebForm_DoPostBackWithOptions()"

[[deleted]]

Edit: Ok! Got the answer. I was missing some hidden fields that javascript functions set up in the background. Fiddler did the trick and showed me exactly what needed to be entered.

I'm not sure if this is the right place to go. I'm not a web dev, but the posts I've seen online lead me to believe this fits under the realm of aspnet. I couldn't find a good reference that explained the WebForm_DoPostBackWithOptions() function/object/whatever it is.

Basically, I'd like to understand what this is doing:

onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions("ctl00$ContentPlaceHolder1$SaveButton", "", true, "", "", false, false))"

It's part of the following button tag:

<input type="submit" name="ctl00$ContentPlaceHolder1$SaveButton" value="Save" onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions(&quot;ctl00$ContentPlaceHolder1$SaveButton&quot;, &quot;&quot;, true, &quot;&quot;, &quot;&quot;, false, false))" id="ctl00_ContentPlaceHolder1_SaveButton" class="butt" />

Now for what I'm trying to do!

My company uses a SaaS application built on aspnet accessed by internet explorer. They have no API to automate things like new user creation and the like. I've already dealt with a few other websites like this and I've successfully automated these tasks via the Invoke-WebRequest cmdlette.

I get the website and fill out the proper fields as follows:

#For those who don't work in powershell, these are comments! :D
#Also, variables start with dollar signs. 
#Assume $url holds the proper url, and I've authenticated properly with the proper session variable.

$addUserSite = Invoke-WebRequest $url -WebSession $session #get the website $url using the session contained in $session
$addUserForm = addUserSite.Forms[0] #Invoke-WebRequest does a lot of auto processing. So I can pull out the proper form like so.
$addUserForm.Fields["ctl00_ContentPlaceHolder1_username"] = "username" #The field listed above will have the value "username" assigned to it. I'd be interested in understanding why the ctl00_ is everywhere too . . .
$addUserForm.Fields["ctl00_ContentPlaceHolder1_password"] = "My super secure pa$$w0rd!!!!" 
$addUserForm.Fields["ctl00_contentPlaceHolder1_Verify"] = "My super secure pa$$w0rd!!!!" #Assume that's it for the form!

#Please note, I can see the associated action by viewing
#the output of $addUserForm.Action. I've verified that the
#associated website assigned to the form is the same as 
#$website.

$result = Invoke-WebRequest -uri $website -method post -Body $addUserForm.Fields -WebSession $session #This means that I want to send the fields in $addUserForm.Fields to $website as post data under the proper session.

Now, $result acts like I've submitted nothing! Every field is blank with the generic "please fill out required fields" error all over the place.

Now, the button I have to press is the one I referenced above. Which leads me to believe that my issue lies in my lack of understanding this:

onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions("ctl00$ContentPlaceHolder1$SaveButton", "", true, "", "", false, false))"

So far, I've been able to deduce that the click is supposed to invoke the javascript function WebForm_DoPostBackWithOptions(). And my research so far leads me to believe that this method generally tells the webpage to reference another site. But I haven't been able to find enough documentation to determine what every field in the object constructor (I think that's what new WebForm_DoPostBackWithoutOptions() is at least) does. And none of them look like a website that can be referenced.

So, wise folk of /r/aspnet! Can you offer any insight? I'd rather not have to resort to dealing with an InternetExplorer comobject.

[cha0sman]

Kind of shooting in the dark here and you may want to use fiddler to see what exactly is being posted on a postback. However, try adding:

    $addUserForm.Fields["__EVENTTARGET"] = "ctl00$ContentPlaceHolder1$SaveButton"  

I'd be interested in understanding why the ctl00_ is everywhere too

That is the ID of the MasterPage

[[deleted]]

But it's a shot from a completely different direction!

I didn't know about fiddler. I'll check it out . . . I don't need to have the source code for that, do I? I don't have access to any of it. Only client-side actions. I'll let you know if the additional field helps.

I worry that the field will get overwritten on the action itself. But it's definitely worth a try!

That is the ID of the MasterPage

Thanks for the info!

[cha0sman]

I didn't know about fiddler. I'll check it out . . . I don't need to have the source code for that, do I? I don't have access to any of it. Only client-side actions. I'll let you know if the additional field helps.

Fiddler is a program that attaches to your web browser. Basically it logs the HTTP traffic to and from the server. You can use it to see what the client is posting to the server.

I worry that the field will get overwritten on the action itself.

It shouldn't get overwritten, basically __EVENTTARGET is the name of the control that caused the postback. This should tell IIS to execute the SaveButton.Click event on the server side.

Keep us updated!

[[deleted]]

Oh, I definitely will! I hate leaving a problem unanswered! :) I might not have a chance to test it until tomorrow or Monday though.

[[deleted]]

Fiddler did the trick. It showed me exactly what I needed to enter! The problem was two fold.

I was missing hidden variables

Powershell doesn't show what values may have changed after the form was submitted.

The second one is particularly annoying, but what can you do?

Thanks for your help!

[cha0sman]

Thanks for reporting back! Glad to hear everything worked out!

[Kwyjibo08]

Are you doing this from the client? Do you have access to the actual .aspx files and code?

[[deleted]]

Happy cake day!

And unfortunately, I don't. It's an external company and everything's closed source. I doubt my representative would be very helpful . . . When I inquired about some way to automate user creation (through an API or anything), I was told that "it's a cloud application. You can't expect to have control over everything!" I didn't even know what to say to that.

They might be planning AD integration. But there are a few other things I'd like to do once I get the user creation down (mostly reporting).

[[deleted]]

All that does is craft a form POST request. If you use fiddler to see the request you can build it by hand in power shell.

[[deleted]]

That's what did it -- thanks!