Insert new XML data using an XPath

[rcronk]

I'm new to C#/.NET. I am writing some C#/.NET (2.0) classes that will allow someone to get and set values in an XML file using an XPath to point to the location of that data. It's more complicated than this but for simplicity's sake, I've trimmed it down to this.

The problem I'm running into is I want to find the best way to add the data into the XML file if the XPath returns nothing. For example, some XPaths might already exist in the XML file, so I can easily use XmlDocument.Sel ectNodes() to give me a list of the nodes that match and then I can get/set the Value on that node if it's an attribute or InnerText if it's an element, for example.

So, if someone wants to set some data into the XML and SelectNodes() returns nothing, what's the best way for me to add that node where the XPath says it should go? There may be a simple way in the .NET 2.0 framework, but I haven't been able to find it. Since SelectNodes() returns nothing, I don't have a position to insert the data into. I thought of taking off the rightmost part of the XPath and try again, repeating until I get something back and then insert each piece back out to the full XPath, but that seemed kludgy. It would be cool to just have a CreateNode(XPat h, value) or something like that. Ideas?

Here's a simple example:

<a>
  <b>
    <c>Blah</c>
  </b>
</a>

XPath "/a/b/c" would allow us to get/set the Blah value. Fine.

XPath "/a/b/d" would return nothing but the user would want it to create <d> as a sibling of <c> and set/get its value.

[rcronk]

To summarize, (and to get this thread back up to the top again so it has a chance of being answered ;-)) I want to be able to query with xpath and if nothing is found, I want to know, given that specific xpath, the easiest way to insert a node at that xpath location.

[rcronk]

Is anyone out there.......

[Shashi Sadasivan]

Hi,
Have you tried the XPathDocument along with the XPathNavigator class?

More info can be found at How To Query XML with an XPath Expression by Using Visual C# .NET

I havent yet used this for editing xml files, but i hope it can be done.
Do post back if you face any further issues

[rcronk]

Hi,
Have you tried the XPathDocument along with the XPathNavigator class?

More info can be found at How To Query XML with an XPath Expression by Using Visual C# .NET

I havent yet used this for editing xml files, but i hope it can be done.
Do post back if you face any further issues

Unfortunately, I didn't see a way at that link to insert a node that doesn't currently exist by just using an xpath expression. Could you post a few sample source code lines in C# that would insert the node that the xpath "/a/b/d" would point to into the following XML (same example as above) just using the xpath :

<a>
  <b>
    <c>Blah</c>
  </b>
</a>

The output XML after the insert would be:

<a>
  <b>
    <c>Blah</c>
    <d></d>
  </b>
</a>

I have yet to find a way to insert <d></d> without parsing the xpath myself to get it down to "/a/b" to find a place where I could insert the "d" child - which I also have to parse off of the xpath. I don't want to parse xpath expressions manually in order to be able to insert a non-existent node because either I'll have to write a full xpath parser to be sure I'm doing it correctly, or it will fail when it comes across a more complicated xpath as input.

[rcronk]

bump - anyone out there?