getnodebyxpath throws nullreferenceexception

Press Ctrl / CMD + C to copy this to your clipboard.

Copied to clipboard

Flag this post as spam?

This post will be reported to the moderators as potential spam to be looked at

Aximili 177 posts 278 karma points

Jun 02, 2015 @ 12:52

I'm working on a project using Umbraco 6 and WebForms.

In Content, there are Employees. So umbraco.config contains these lines:

  <Employee id="15853" ...>
    <email>xxx</email>
  </Employee>

In C#, how do I get the Employee node having email=xxx? I tried this:

Node nodeEmail = Node.GetNodeByXpath("//Member/email[text()='xxx']");

and it throws this exception:

[NullReferenceException: Object reference not set to an instance of an object.]
   umbraco.NodeFactory.Node.initialize() +172
   umbraco.NodeFactory.Node..ctor(XmlNode NodeXmlNode) +179
   umbraco.NodeFactory.Node.GetNodeByXpath(String xpath) +168

Copy Link

Chriztian Steinmeier 2800 posts 8790 karma points MVP 8x admin c-trib

Jun 02, 2015 @ 12:56
0
Hi Hardi,

In the XPath expression you need to use the document type's alias (i.e. "Employee") - so if it's <Employee> in the XML, it should be Employee in the expression, i.e.:
```
Node nodeEmail = Node.GetNodeByXpath("//Employee/email[. = 'xxx']");
```
/Chriztian
Copy Link
Aximili 177 posts 278 karma points

Jun 02, 2015 @ 15:20
0
Oh I'm sorry I cut and pasted the wrong thing. I can't edit it anymore.

It was already Employee. But it throws a NullReferenceException.

These lines are fine:
```
Node nodeEmail = Node.GetNodeByXpath("//Employees");
```
```
Node nodeEmail = Node.GetNodeByXpath("//Employees/Employee");
```
```
Node nodeEmail = Node.GetNodeByXpath("//Employee");
```
But this throws NullReferenceException
```
Node nodeEmail = Node.GetNodeByXpath("//Employees/Employee/email");
```
Copy Link
Sebastian Dammark 583 posts 1407 karma points

Jun 02, 2015 @ 18:52
2
Try this:
```
Node nodeEmail = Node.GetNodeByXpath("//Employee[email = 'xxx']");
```
Copy Link
Aximili 177 posts 278 karma points

Jun 03, 2015 @ 14:08

0

It works! Thank you Sebastian!

I still don't understand why the other queries were throwing the exception, even though they were fine when tested on XPath testers. But thanks!

Copy Link
Chriztian Steinmeier 2800 posts 8790 karma points MVP 8x admin c-trib

Jun 03, 2015 @ 14:17

1

Hi Hardi,

The error you get is because the code that deals with an umbraco Node, and all of the working XPath expressions return a node - the ones throwing an error, selects a property instead. I didn't catch that your code was using a node (the "nodeEmail" name threw me off, I guess :-). Sebastian's XPath selects the <Employee> node that has an <email> equal to 'xxx', whereas mine selected the actual <email> element. Subtle difference - but if your C# code expects a Node, the error message makes perfect sense.

Does that help understanding?

/Chriztian

Copy Link
Aximili 177 posts 278 karma points

Jun 04, 2015 @ 01:47

0

Ah of course! I was concentrating too much on the XML I forgot about the Node itself! Thank you Chriztian :)

Copy Link
is working on a reply...

Please Sign in or register to post replies