Linq Query to display string from XML in a TextBox

Question

I'm trying to make a Linq query that will retrieve a string value from an XML file and place it in a TextBox. I think I need to use FirstorDefault(), but I can't figure out how to use it properly. Here is what I have at the moment:

var comm = from comment in xdoc.Descendants("string")                   
           where comment.Attribute("id").Value == tagBox.Text
           select comment.Element("comment").Value;

textBox.Text = comm; //Essentially

Basically, my XML file looks like this:

<root>
    <string id = "STRING_ID1">
        <element1 />
        <comment> Some string </comment>
        ...
    </string>
</root>

In the first code snippet, tagBox refers to another TextBox that has a string in it which was originally pulled from the id attribute of my string element. The idea is to scan the XML for the matching ID, and simply put the value of the comment element in the textBox.

Peter · Accepted Answer · 2011-08-03 19:28:22Z

3

Just change

textBox.Text = comm;

to

textBox.Text = comm.FirstOrDefault();

answered Aug 3, 2011 at 19:28

Peter

3,9661 gold badge25 silver badges44 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

DaveShaw Over a year ago

comm is an XElement, not an IEnumerable<XElement> because he is using Element("comment").

Sean Glover Over a year ago

Actually comm IS an IEnumerable<XElement>, and that was my issue.

Jeff Mercado Over a year ago

@Dave: It's actually IEnumerable<string>... it was projected to the Value of the XElement.

Peter Over a year ago

@DaveShaw: No, comm is an IEnumerable<string>. comment.Element("comment").Value is only in the select part of the linq query!

dvdvorle · Accepted Answer · 2011-08-03 19:31:09Z

1

Usage of FirstOrDefault would be as follows

var str = (from str in xdoc.Descendants("string")                   
           where str.Attribute("id").Value == tagBox.Text
           select str).FirstOrDefault();

if(str != null)
{
    textBox.Text = str.Element("comment").Value;
}
else
{
    textBox.Text = "";
}

edited Aug 3, 2011 at 19:31

answered Aug 3, 2011 at 19:25

dvdvorle

9711 gold badge12 silver badges27 bronze badges

4 Comments

Tim Over a year ago

Is .Value == tagBox.Text valid in the LINQ expression? I would have thought .Contains(tagBox.Text) would be the way to put run-time values into the query.

dvdvorle Over a year ago

@DaveShaw, you're right, I forgot to remove it. The whole semantics of the code weren't right anyway so I changed it all around.

dvdvorle Over a year ago

@Tim: they're both possible, but they are semantically different. "==" is exact match, and ".Contains()" would be more of a wildcard match. If you want to specify culture and have an exact match I'd use ".Equals()"

Tim Over a year ago

@Mr Happy - thanks for the info. I didn't realize the differences. Good stuff to know.

Collectives™ on Stack Overflow

Linq Query to display string from XML in a TextBox

2 Answers 2

4 Comments

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related