Click button after webBrowser1_DocumentCompleted event

Question

I have a C# 4.0 WinForms application, which has a WebBrowser control and 2-buttons.

Clicking the first button sends a URL to the browser to navigate to a specified webSite.

Clicking the second button parses the OuterHtml of the webBrowser1.Document, looking for an "https://..." link for File Download.

The code then uses a webClient.DownloadFileAsync to pull down a file for further use in the application.

The above code successfully works, if I manually click those buttons.

In an effort to automate this for the end-user, I place the first button's click event, i.e. btnDisplayWeb.PerformClick(); in the form's Form1_Load event. This also works, allowing the webBrowser1 to populate its Document with the desired webSite.

However, I am unable to programatically click the 2nd button to acquire the web link for file download.

I have tried to place the 2nd buttons click event within the browser's DocumentCompleted event, as shown below.

private void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
    btnMyUrl.PerformClick();
}

However, from what I've read on StackOverFlow and other sites, it's possible that this particular event gets called more than once, and hence it fails.

I've also attempted to loop for a number of seconds, or even use a Thread.Sleep(xxxx), but the browser window fails to populate until the sleep or timer stops.

I attempted to use the suggestions found on the following StackOverFlow site shown below.

How to use WebBrowser control DocumentCompleted event in C#?

private void webBrowser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
    string url = e.Url.ToString();
    if (!(url.StartsWith("http://") || url.StartsWith("https://")))
    {
        // in AJAX
    }

    if (e.Url.AbsolutePath != this.webBrowser.Url.AbsolutePath)
    {
        // IFRAME 
    }
    else
    {
        // REAL DOCUMENT COMPLETE
    }
}

However, in parsing the OuterHtml, nothing is returned in the first two sections, and in the third section, other elements are returned instead of the desired "https://..." link for File Download.

Interestingly, if I use a webBrowser1.ReadyState event, as shown below, and place a MessageBox inside DocumentCompleted, this seems to allow the browser document to complete, because after clicking the OK button, the parsing is successful.

if (webBrowser1.ReadyState == WebBrowserReadyState.Complete)
{
    MessageBox.Show("waiting", "CHECKING");
    btnMyUrl.PerformClick();
}

However, I then have the difficulty of finding a way to click the OK button of the MessageBox.

Is there another event that occurs after the DocumentCompleted event. OR, can someone suggest how to programmatically close the MessageBox?

If this can be done in code, then I can perform the buttonClick() of the 2nd button in that section of code.

score 0 · Accepted Answer · answered Feb 23 '21 at 21:51

After finding that the addition of a MessageBox allows the webBrowser1.Document to complete, and using webBrowser1.ReadyState event within the webBrowser_DocumentCompleted event, all I needed to do, was to find a way to programmatically close the MessageBox.

Further searching on StackOverFlow revealed the following solution on the site below.

Close a MessageBox after several seconds

Implementing the AutoClosingMessageBox, and setting a time interval, closed the MessageBox and allowed my button click, i.e. btnMyUrl.PerformClick(); to successfully parse the OuterHtml and now the code works properly.

Hopefully, if someone else discovers that placing a MessageBox within the webBrowser_DocumentCompleted event allows the document to complete; the aforementioned AutoClosingMessageBox will assist them as well.

Click button after webBrowser1_DocumentCompleted event

1 Answers1