C# Using XPATH to select specific element with known values, then delete
I am new to xpath in C# and I am trying to select an element that has two specific values. This is what the XML format looks like
<?xml version="1.0" encoding="utf-8"?>
<Manager>
<SSH>
<Tunnels>
<Port>
<Local>443</Local>
<Remote>443</Remote>
</Port>
<Port>
<Local>5432</Local>
<Remote>5432</Remote>
</Port>
<Port>
<Local>19</Local>
<Remote>21</Remote>
</Port>
<Port>
<Local>19</Local>
<Remote>22</Remote&g开发者_StackOverflowt;
</Port>
</Tunnels>
</SSH>
</Manager>
I was trying to select a 'Port' that had the values from a previous form so i can delete that specific entry from the xml. This was the code i was using:
//remove children from selected
XmlNode _xmlTunnel = _xml.SelectSingleNode("/Manager/SSH/Tunnels/Port[Local=" + _local + "] | /Manager/SSH/Tunnels/Port[Remote=" + _remote + "]");
MessageBox.Show("Local " + sshList.SelectedItems[0].Text + " Remote " + sshList.SelectedItems[0].SubItems[1].Text +"\n\n" + _xmlTunnel.InnerText);
_xmlTunnel.RemoveAll();
//remove all empties
XmlNodeList emptyElements = _xml.SelectNodes(@"//*[not(node())]");
for (int i = emptyElements.Count -1; i >= 0; i--) {
emptyElements[ i ].ParentNode.RemoveChild(emptyElements[ i ]); }
This code works fine until I have two Ports with the same Local Value. It always selects the first element that it comes to (i.e. Local=19 and Remote=21, even if you try to select the node where Local=19 and Remote=22). I tried switching the xpath expression to 'and' instead of '|' in the SelectSingleNode method but that errors out with a "Expression must evaluate to a node-set". Which makes me think that I am evaluating out to a boolean when I use 'and'.
Is the better way to do this by a loop where a select the first element and loop until the second one matches? As I said before i do not have much experience with xpath/xml expressions in C#, perhaps there is a better way. If it helps I am using windows forms and .net 4.0, in this form the port values fill a two column list view in detail view.
You need to "and" 2 conditions on Port node like:
"/Manager/SSH/Tunnels/Port[Local=" + _local + " and Remote=" + _remote + "]"
In your case you are doing union of 2 sets where Local=19 and another where Remote=21.
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