How to delete specific nodes from an XElement?

Question

I have created a XElement with node which has XML as below.

I want to remove all the "Rule" nodes if they contain "conditions" node.

I create a for loop as below but it does not delete my nodes

foreach (XElement xx in xRelation.Elements())
{
  if (xx.Element("Conditions") != null)
  {
    xx.Remove();
  }
}

Sample:

<Rules effectNode="2" attribute="ability" iteration="1">
    <Rule cause="Cause1" effect="I">
      <Conditions>
        <Condition node="1" type="Internal" />
      </Conditions>
    </Rule>
    <Rule cause="cause2" effect="I">
      <Conditions>
        <Condition node="1" type="External" />
      </Conditions>
    </Rule>
</Rules>

How can I remove all the "Rule" nodes if they contain "conditions" node?

you can't iterate rule elements with foreach while deleting the items. rather you can collection them in a list and the iterate using for loop and delete them. — Rohit Prakash, Jan 27 '15 at 11:21

Andrey Korneyev · Accepted Answer · 2017-02-14T07:17:18.083

18

You can try this approach:

var nodes = xRelation.Elements().Where(x => x.Element("Conditions") != null).ToList();

foreach(var node in nodes)
    node.Remove();

Basic idea: you can't delete elements of collection you're currently iterating.
So first you have to create list of nodes to delete and then delete these nodes.

edited Feb 14 '17 at 07:17

answered Jan 27 '15 at 11:23

Andrey Korneyev

26,353
15
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71

score 13 · Answer 2 · answered Jan 27 '15 at 11:25

13

You can use Linq:

xRelation.Elements()
     .Where(el => el.Elements("Conditions") == null)
     .Remove();

Or create a copy of the nodes to delete, and delete them after (in case the first method doesn't work):

List nodesToDelete = xRelation.Elements().Where(el => el.Elements("Conditions") == null).ToList();

foreach (XElement el in nodesToDeletes)
{
    // Removes from its parent, but not nodesToDelete, so we can use foreach here
    el.Remove();
}

answered Jan 27 '15 at 11:25

Kilazur

3,089
1
22
48

I don't think your solution at the top can work. el.Elements("Conditions") == null) will always evaluate to not null. – Ciaran Gallagher Dec 05 '22 at 18:49
@CiaranGallagher well, the answer is 7 years old, but it was upvoted 12 times, so I assume it's been a working solution to OP's issues at the time :) – Kilazur Dec 07 '22 at 17:44

score 3 · Answer 3 · edited Dec 08 '22 at 19:24

3

  passiveLead.DataXml.Descendants("Conditions").Remove();

This will remove all descendant elements that match the name 'Conditions' for the XML document.

edited Dec 08 '22 at 19:24

Ciaran Gallagher

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answered Nov 02 '15 at 20:18

user2700757

89
7

3

Can you please add some additional explanation or references for the OP and future readers? – Ryan Gates Nov 02 '15 at 22:29

score 2 · Answer 4 · answered Jan 27 '15 at 11:24

2

I've made a small example for you:

XDocument document = XDocument.Parse(GetXml());
var rulesNode = document.Element("Rules");
if (rulesNode != null)
{
    rulesNode.Elements("Rule").Where(r => r.Element("Conditions") != null).Remove();
}

answered Jan 27 '15 at 11:24

Tomtom

9,087
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score 1 · Answer 5 · answered Dec 22 '18 at 11:24

1

var el = xRelation.XPathSelectElement("/Rules/Rule/Conditions");
while (el != null)
{
      el.Remove();
      el = xRelation.XPathSelectElement("/Rules/Rule/Conditions");
}

answered Dec 22 '18 at 11:24

Mihal By

162
2
12

score -1 · Answer 6 · answered Jan 08 '19 at 06:48

-1

just an idea:

Reverse the Linq "condition" and You will get a List without "Rule" nodes

answered Jan 08 '19 at 06:48

Hans

1

Hi! Small answers must go in comments section. Please wait till you have enough reputation to comment. See https://stackoverflow.com/help/how-to-answer – Ankur Aggarwal Jan 08 '19 at 07:14

How to delete specific nodes from an XElement?

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