Question
Using HTML Agility Pack and LINQ, I'm attempting to get all cells from an HTML table. I've used LINQ to pick the tags from the HTML source that I imported into a HtmlAgilityPack.HtmlDocument. However, it crashes in the second record after using foreach to iterate the result.
A portion of the HTML source is shown here:
<tr>
<td class='city'>New York</td>
<td>Card 1</td>
</tr>
<tr>
<td class='city'>London</td>
<td>Card 2</td>
</tr>
<tr>
<td class='city'>Tokyo</td>
<td>Card 3</td>
</tr>
<tr>
<td class='city'>Berlin</td>
<td>Card 4</td>
</tr>
This is what I created:
htmlDoc.LoadHtml(await msgRecived.Content.ReadAsStringAsync());
var tds=
from td in htmlDoc.DocumentNode.Descendants("td")
where td.Attributes["class"].Value == "city"
select td.InnerText;
foreach (var td in tds)
{
citiesText = citiesText + " " + td;
}
If I use the following syntax instead of the foreach command:
citiesText = tds.ElementAt(0);
It returns A new York but crashes with Reference to an instance of an object not set. when I attempt ElementAt(1).
Any help? Thanks
Accepted Answer
You must make certain thatAttributes["class"]
is notnull
:
var tds =
from td in doc.DocumentNode.Descendants("td")
where td.Attributes["class"] != null && td.Attributes["class"].Value == "city"
select td.InnerText;
The following<td>
Recovered has noclass
so that whenever you accessAttributes["class"]
Consequently, you're receivingnull
the call.Value
on null
is the source of the exception.
As an alternative, you mayGetAttributeValue
:
var tds =
from td in doc.DocumentNode.Descendants("td")
where td.GetAttributeValue("class", null) == "city"
select td.InnerText;
Popular Answer
Just a hunch, but I think you're just focusing on the first element's td. Perhaps you need
Instead, use htmlDoc.DocumentNode.Descendants("table").
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