尝试使用linq将xml修改为xml和xpath

Question

I am not able to modify xml using linq to xml. Here's the code i am using:

In below code Parameters[0] has value 'payments'

XElement modMethodXElement = new XElement(xdoc1.XPathSelectElement("//INPUT[@VALUE='SLN7DEACTIVATION']/METHOD[@NAME='"+Parameters[0]+"']"));
                modMethodXElement.SetAttributeValue("PARAMETERS", "ParameterValue");

And here's part of xml i am trying to modify:

SESSIONANALYSER>
  <AP>
    <MODES>
      <NI>
        <STATEINFORMATION TYPE="PREPAID">
          <INIT INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="SLN7ACTIVATION">
              <METHOD NAME="CHECKSUBSCRIBERBALANCE" PARAMETERS="SLN7" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SETPSOINUCIP" PARAMETERS="SLN7" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="SLN7DEACTIVATION">
              <METHOD NAME="UNSETPSOINUCIP" PARAMETERS="SLN7" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              ***<METHOD NAME="payments" PARAMETERS="fsdg" POSSIBLEACTIONS1="fg,f" MAINTAINSESSION="fdjfg89" RESPONSE="ndfgm" NEXTLEVEL="msdfm"></METHOD>***
              <METHOD NAME="SENDMESSAGE" PARAMETERS="23" POSSIBLEACTIONS1="FALLOUTONSUCCESS" MAINTAINSESSION="yes" RESPONSE="format" NEXTLEVEL="msdfm"></METHOD>
              <METHOD NAME="payments" PARAMETERS="12" POSSIBLEACTIONS1="FALLOUTONSUCCESS" MAINTAINSESSION="yes" RESPONSE="format" NEXTLEVEL="msvm"></METHOD>
              <METHOD NAME="SENDMESSAGE" PARAMETERS="23" POSSIBLEACTIONS1="FALLOUTONSUCCESS" MAINTAINSESSION="yes" RESPONSE="0" NEXTLEVEL="3"></METHOD>
              <METHOD NAME="SENDMESSAGE" PARAMETERS="23" POSSIBLEACTIONS1="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="format" NEXTLEVEL="3"></METHOD>
            </INPUT>
          </INIT>

Answer 1

I'm not sure why you want to create a new instance of XElement? I would simply select the given element like this, and xdoc1 will contain the changed attribute after.

        XElement modMethodXElement = xdoc1.XPathSelectElement("//INPUT[@VALUE='SLN7DEACTIVATION']/METHOD[@NAME='" + arg + "']");

        modMethodXElement.SetAttributeValue("PARAMETERS", "ParameterValue");