WebBrowser Control c#: finding particular link and "clicking" it programmatically?

Question

I am working on csv downloader project ,i need to download the CSV files generated on the webpage . and using html agility , i found the exact link that contain the link for csv file

<a href="/content/fo/contractvol/datafiles/OPTIDX_NIFTY_CE_31-08-2012_TO_31-08-2012.csv" target="_blank">Download file in csv format</a>

now i want , without any activity from my side , the application must detect this link in the web page ( i could do it by Htmlagility ) and should download the file once the web page fully navigated in Web browser in my app. I tried some example in one of the SO click here post but getting

Error :Object reference not set to an instance of an object.

HtmlElementCollection links = webBrowser.Document.GetElementsByTagName("A"); foreach (HtmlElement link in links) // this ex is given another SO post { if (link.InnerText.Equals("My Assigned")) link.InvokeMember("Click"); }

Can any body suggest how to do it ??

Solved :

I changed to HtmlElementCollection links = webBrowser.Document.GetElementsByTagName("A"); to HtmlElementCollection links = webBrowser1.Document.Links and used

 if (link.InnerText.Contains("My Assigned")) { link.InvokeMember("Click"); }

. any one who better solution?

rene · Accepted Answer · 2012-09-01 12:05:08Z

1

InnerText might be null so build in a safeguard, to check for null:

if ((link.InnerText != null) && (link.InnerText.Equals("My Assigned")) ) link.InvokeMember("Click");

answered Sep 1, 2012 at 12:05

rene

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3 Comments

Vishwa Over a year ago

I changed to HtmlElementCollection links = webBrowser.Document.GetElementsByTagName("A"); to HtmlElementCollection links = webBrowser1.Document.Links it worked . i sthis a best practice ??

rene Over a year ago

You would almost think that GetElementsByTagname is case sensitive. Links is an alternative but it would not only give you Anchors (A) but also LINK and AREA tags, as stated in the msdn doc In your case it is a fine solution.

Erx_VB.NExT.Coder Over a year ago

@Vishwa TagName refers to the name attribute/property of any particular tag, just like TagId refers to the ID attribute/property of any Tag. Since there are unlikely to be tags with the name="A", you are getting that object error. Check out my answer.

Erx_VB.NExT.Coder · Accepted Answer · 2012-09-04 01:51:32Z

Actually, I would get rid of HTMLAgility pack (its pretty bad) and just go/loop through it yourself. Also, don't use innerText, because based on your examples, there doesn't seem to be an innertext in at least one of the links. Use the .href attribute and check for the .csv extension.

link.href.EndsWith(".csv")

And if there are more than one .cvs on each page, look for some url string or innertext property to refine it.

Also, the reason why your .GetElementsByTagName("A") was not working was because TagName refers to the name attribute of any particular TAG. So, you were saying, Get all TAG's with the TagType name="A"... does that make sense? I think there is a .GetElementsByTag[Type] or something like that which you can use to base it on the tag type and not the name attribute of a TAG.

Also, how are you downloading the .csv file? Is a "download dialog" box coming up or are you just showing people in the webbrowser control? (curious how you've handled that part).

Your link.href is not at all working and it showing Error 1 'System.Windows.Forms.HtmlElement' does not contain a definition for 'href' and no extension method 'href' accepting a first argument of type 'System.Windows.Forms.HtmlElement' could be found
@vishwa that is because you are trying to do a .href on a tag that is not an anchor tag, ie: if in your loop you are at a DIV tag, you can't do a .href on that, you need to make sure you it's an A tag, and when you declare it, dont' use HtmlElement, since it's a link, you can usethe appropriate Declaration for that (HtmlAnchorElement or whatever it's called, can't remember the exact name, you will see it in intellisense).

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