C# - WebBrowser manipulation, setting/getting attributes, clicking elements, etc...

[detlion1643]

I've been doing a lot of application development with WebBrowsers lately. I also notice the occasional thread that pops up asking how to do stuff regarding the 'net (login to a site, click something on a site, etc).

First thing is first, let's create a WebBrowser and navigate it to here:

//new WebBrowser, or add the control to a form instead
System.Windows.Forms.WebBrowser wb = new System.Windows.Forms.WebBrowser;
//Hook the document completed event so we know when a page is completely loaded up
wb.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(wb_DocumentCompleted);
//Navigate to google
wb.Navigate("http://www.vbforums.com");

private void wb_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{

}

Now, let's see how to work with the document of the webpage in order to fill in the correct values for logging in.

There are a couple of ways to do this. First off, if the element has an "id=***", we know that the same id can not exist anywhere else on the same page. So:

//inside of the document completed event
//here's the html for the username: <input type="text" class="textbox default-value" name="vb_login_username" id="navbar_username" size="10" accesskey="u" tabindex="101" value="User Name" />
//here's the html for the password: <input type="password" class="textbox" tabindex="102" name="vb_login_password" id="navbar_password" size="10" />
//here's the html for the button to click: <input type="submit" class="loginbutton" tabindex="104" value="Log in" title="Enter your username and password in the boxes provided to login, or click the 'register' button to create a profile for yourself." accesskey="s" />

//fill in the value for the username element
((WebBrowser)sender).Document.GetElementById("navbar_username").SetAttribute("value", "username");
//fill in the value for the password element
((WebBrowser)sender).Document.GetElementById("navbar_password").SetAttribute("value", "password");
//click the login element
HtmlElementCollection htmlcol = ((WebBrowser)sender).Document.GetElementsByTagName("input");
for (int i = 0; i < htmlcol.Count; i++)
            {
                if (htmlcol[i].GetAttribute("value") == "Log in")
                {
                    htmlcol[i].InvokeMember("click");
                }
            }

Of course, if an element doesn't have an "id=***", we can still get to the element. We just need to figure out what property/attribute we can use to identify them apart.

//inside of the document completed event
//here's the html for the text to fill in to search for (without id): <input type="text" class="textbox default-value" name="vb_login_username" size="10" accesskey="u" tabindex="101" value="User Name" />
//here's the html for the password (without id: <input type="password" class="textbox" tabindex="102" name="vb_login_password" size="10" />
//here's the html for the button to click (without id): <input type="submit" class="loginbutton" tabindex="104" value="Log in" title="Enter your username and password in the boxes provided to login, or click the 'register' button to create a profile for yourself." accesskey="s" />

//get a collection of the input elements on the page
HtmlElementCollection htmlcol = ((WebBrowser)sender).Document.GetElementsByTagName("input");
//loop the input elements
for(int i=0; i<htmlcol.Count; i++)
{
	if (htmlcol[i].Name == "vb_login_username") //this is the only element with a name of "vb_login_username"
	{
		htmlcol[i].SetAttribute("value", "username");
	}
        else if (htmlcol[i].Name == "vb_login_;password") //this is the only element with a name of "vb_login_username"
	{
		htmlcol[i].SetAttribute("value", "password");
	}
}

//click the login element

for (int i = 0; i < htmlcol.Count; i++)
            {
                if (htmlcol[i].GetAttribute("value") == "Log in")
                {
                    htmlcol[i].InvokeMember("click");
                }
            }

You can use the above and modify it to any ID, or any element you can identify. This is how you can login to websites and the such.

*Remember, pretty much any element can accept clicks. If the element you need to click is an <img *** *** *** > element, just loop the "img" tag collections instead of "input" or "button" and call the same .InvokeMember("click");

------

There a lot of other elements we can manipulate as well. Radio buttons, checkboxes, and dropdown lists I have manipulated in my applications before. It's the same concept in general.

Dropdown lists:
//this is the dropdown list for the "Show threads from the ..." at the bottom of the codebank sub forum I'm currently looking at

//inside a document completed event
//get a collection of the parent "select" elements first
HtmlElementCollection htmlcol = ((WebBrowser)sender).Document.GetElementsByTagName("select");
for(int i=0; i<htmlcol.Count; i++)
{
	if(htmlcol[i].Name = "daysprune") //if the select element is the dropdown we need to select something for
	{
		//create another element collection for the child elements of the "select" element
		HtmlElementCollection htmlcolchild = htmlcol[i].Children;
		for(int j=0; j<htmlcolchild.Count; j++)
		{
			//<option value="1" >Last Day</option>
				//...
			//<option value="-1" selected="selected">Beginning</option>

			//*** Notice the selected="selected" part

			//if we want to select the "Last Day" instead
			if(htmlcolchild[j].InnerText == "Last day") //inner text gets the text between the beginning/end of the element without the attributes
			{
				htmlcolchild[j].SetAttribute("selected", "selected") //set the selected attribute for the last day, instead of the "beginning"
				break;
			}
		}
	}
}

//to make the changes go through, we need to click the "show threads" element
//<input type="submit" class="button" value="Show Threads" />
htmlcol = ((WebBrowser)sender).Document.GetElementsByTagName("input");
for(int i=0; i<htmlcol.Count; i++)
{
	if(htmlcol[i].GetAttribute("value") == "Show Threads")
	{
		htmlcol[i].InvokeMember("click");
		break;
	}
}

I hope this helps people out! Some of it caused me great fustration when I learned it.