Using GetElementsById to search a website

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C#

{
            string entry = Titleentry.Text;

            HtmlElementCollection theElementCollection;
            HtmlDocument filters = webBrowser1.Document;

            theElementCollection = webBrowser1.Document.GetElementsByTagName("input");

            foreach (HtmlElement curElement in theElementCollection)
            {
                if ((curElement.GetAttribute("id").ToString() == "searchTitle"))
                {
                    curElement.SetAttribute("value", entry);
                }
            }
filters.GetElementById("filterSortBy").GetAttribute("option").Select("price_low_high");


            //foreach (HtmlElement curElement in option)
            //{
            //    if option = ("price_low_high");
            //}

            theElementCollection = webBrowser1.Document.GetElementsByTagName("button");

            foreach (HtmlElement curElement in theElementCollection)
            {
                if (curElement.GetAttribute("id").Equals("searchSubmit"))
                {
                    curElement.InvokeMember("click");
                }
            }

the marked statement gives me the following message:

Error 1 The type arguments for method 'System.Linq.Enumerable.Select(System.Collections.Generic.IEnumerable, System.Func)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

what I am trying to do is get elements by ID from a website since if I try elements by tag name it is choosing the incorrect element

I tried using html collections but it says cannot implicitly convert html elements to html collections

Update:

The sample of the HTML code:

<select name="searchSortBy" id="filterSortBy"> 
  <option value="popularity" label="Most popular" selected="selected">Most popular</option> 
  <option value="price_low_high" label="Price, low to high">Price, low to high</option> 
  <option value="price_high_low" label="Price, high to low">Price, high to low</option> 
</select>

thanks

Posted 24-Oct-13 1:35am

slayasty

Updated 24-Oct-13 4:01am

Timberbird

v4

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Comments

Timberbird 24-Oct-13 8:21am

Looks like the problem is in this part: .Select("price_low_high"). GetAttribute("option") returns a string containg the value of the "option" attribute, and then you try to select something from that string. I must admit I don't understand what you are trying to achieve with this method call, but anyway String.Select() has different syntax.

slayasty 24-Oct-13 8:42am

what i am trying to do is selecting the option: setting price lowest first from the filters of the website. maybe i need to use different html elements or something?

Timberbird 24-Oct-13 9:27am

So let me guess: you have a structure like the following:
<select id="filterSortBy">
<option value="val1"> Filter type 1 </option>
<option value="val2"> Filter type 2 </option>
<option value="price_low_high"> Sort by price ascending </option>

</select>
,
and you want to select an "option" element that has value "price_low_high" (i.e. the third one), right? Correct me if I'm wrong. It would be good to add sample HTML fragment you're trying to parse to the original question.

slayasty 24-Oct-13 9:51am

yep thats exactly what i want to do. here is the html for the filter sort:

<select name="searchSortBy" id="filterSortBy">
<option value="popularity" label="Most popular" selected="selected">Most popular</option>
<option value="price_low_high" label="Price, low to high">Price, low to high</option>
<option value="price_high_low" label="Price, high to low">Price, high to low</option>
</select>

thanks

Timberbird 24-Oct-13 10:08am

You could try the following:

HtmlElement pElement = (HtmlElement) filters.GetElementById("filterSortBy").GetElementsByTagName("option").Where(pOption => pOption.GetAttribute("value").Equals("price_low_high", StringComparison.InvariantCultureIgnoreCase) ).FirstOrDefault();

slayasty 24-Oct-13 10:31am

mm i did try this tho it gave this error:

System.StringComparison.InvariantCultureIgnoreCase cannot be used like a method

also how was pElement used in that structure since it isnt directly used?

Timberbird 25-Oct-13 3:48am

I believe that's because you wrote something like StringComparison.InvariantCultureIgnoreCase(). As to the code - my bad, I thought HtmlElementCollection implements IEnumerable<t> interface. You can either use foreach/while cycles then, or convert HtmlElementCollection to any collection that supports LINQ queries, e.g.:

List<HtmlElement> pList = new List<HtmlElement>();
foreach (HtmlElement pItem in pCollection)
{
pList.Add(pItem);
}

HtmlElement pElement = (HtmlElement)
pList.Where(pOption => pOption.GetAttribute("value").Equals("price_low_high", StringComparison.InvariantCultureIgnoreCase)).SingleOrDefault();

What do you mean by "pElement isn't directly used"? pElement is the one you're trying to find - "<option>" with ID "price_low_high"

slayasty 25-Oct-13 7:38am

ah i see. regarding pElement since I it is only being declared as an htmlelement and not used in the code directly(forgive my newbieness in this)

I tried that new code and it says that pCollection does not exist in the current context, what do i need to declare? where can i find this collection that supports linq? i have searched google but with no good answer.

another problem that it gives me is System.Windows.Forms.HtmlElementCollection' does not contain a definition for 'pList' and no extension method 'pList' accepting a first argument of type 'System.Windows.Forms.HtmlElementCollection' could be found (are you missing a using directive or an assembly reference?)

thanks and sorry for all the troubles.

Timberbird 25-Oct-13 8:36am

Oh yes, one more line I didn't copy:
HtmlElementCollection pCollection = filters.GetElementById("filterSortBy").GetElementsByTagName("option");

slayasty 25-Oct-13 9:09am

Cannot convert type 'System.Windows.Forms.HtmlElementCollection' to 'System.Windows.Forms.HtmlElement'

the one line htmlelement pElement = (HtmlElement) is saying this.

Timberbird 25-Oct-13 9:32am

Aren't you missing .SingleOrDefault(); part? Could you post the code you have now?

slayasty 25-Oct-13 9:53am

sure, this is the code currently:

string entry = Titleentry.Text;

HtmlElementCollection theElementCollection;
HtmlDocument filters = webBrowser1.Document;

theElementCollection = webBrowser1.Document.GetElementsByTagName("input");

foreach (HtmlElement curElement in theElementCollection)
{
if ((curElement.GetAttribute("id").ToString() == "searchTitle"))
{
curElement.SetAttribute("value", entry);
}
}

List<HtmlElement> pList = new List<HtmlElement>();
foreach (HtmlElement pItem in theElementCollection)
{
pList.Add(pItem);
}

HtmlElement pElement = (HtmlElement)
filters.GetElementById("filterSortBy").GetElementsByTagName("option");
pList.Where(pOption => pOption.GetAttribute("value").Equals("price_low_high", StringComparison.InvariantCultureIgnoreCase)).SingleOrDefault();

Timberbird 25-Oct-13 10:08am

Oh I see. You messed it up a bit. Instead of lines:

List<HtmlElement> pList = new List<HtmlElement>();
foreach (HtmlElement pItem in theElementCollection) { pList.Add(pItem); }
HtmlElement pElement = (HtmlElement)filters.GetElementById("filterSortBy").GetElementsByTagName("option");
pList.Where(pOption => pOption.GetAttribute("value").Equals("price_low_high", StringComparison.InvariantCultureIgnoreCase)).SingleOrDefault();

there must be the following:

HtmlElementCollection pCollection = filters.GetElementById("filterSortBy").GetElementsByTagName("option");
List<HtmlElement> pList = new List<HtmlElement>();
foreach (HtmlElement pItem in pCollection) { pList.Add(pItem); }
HtmlElement pElement =
(HtmlElement) pList.Where(pOption => pOption.GetAttribute("value").Equals("price_low_high", StringComparison.InvariantCultureIgnoreCase)).SingleOrDefault();

slayasty 25-Oct-13 10:27am

oh i see. thats why you where confused when i asked you about the pElement. the format was screwed up so i didnt understand very well :P

i debugged that code and it seems that even tough the price low to high is found, its not setting that option do i need to use setattribute or something like that?

Timberbird 28-Oct-13 7:27am

I guess you need to select this option and submit the form to the server? If I'm right here are two ways to achieve this purpose: invoke "click" event or set "checked" attribute (I believe you must set it to either "true" or "checked")

slayasty 28-Oct-13 7:53am

yea it needs to be select and the form is submitted using the search button. that link will help alot. thanks for all the help you gave me :)

Timberbird 1-Nov-13 5:53am

You're welcome :)

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