CODEWITHSUNDEEP
xpath
Charu
Charu

Reputation: 2717

Object reference not set to an instance of an object when adding element using xpath for xml

I have an xml file and want to add a child element to one of the nodes, don't know why xpath is throwing null exception. It is surely because of i maybe giving wrong xpath value. What would be the xpath to add element here :

XPath i am using:

//SESSIONANALYSER/KER/MODES/NI/STATEINFORMATION[@TYPE='PREPAID']/INIT/INPUT

Here's where i want to add the child element:

<KER> 
    <MODES>
      <NI>
        <STATEINFORMATION TYPE="PREPAID">
          <INIT INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="LP6ACTIVATION">
             **<I have to add a child element here>**

in the following xml:

<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="jk" PARAMETERS="k" POSSIBLEACTIONS1="k" MAINTAINSESSION="h" RESPONSE="l" NEXTLEVEL=";"></METHOD>
              <METHOD NAME="SENDMESSAGE" PARAMETERS="23" POSSIBLEACTIONS1="FALLOUTONSUCCESS" MAINTAINSESSION="yes" RESPONSE="format" NEXTLEVEL="msdfm"></METHOD>
              <METHOD NAME="payments" PARAMETERS="parametervalue" POSSIBLEACTIONS1="fg,f" MAINTAINSESSION="fdjfg89" RESPONSE="ndfgm" NEXTLEVEL="msdfm"></METHOD>
              <METHOD NAME="payments" PARAMETERS="l" POSSIBLEACTIONS1="l" MAINTAINSESSION="l" RESPONSE="l" NEXTLEVEL="l"></METHOD>
              <METHOD NAME="payments" PARAMETERS="l" POSSIBLEACTIONS1="l" MAINTAINSESSION="l" RESPONSE="l" NEXTLEVEL="l"></METHOD>
              <METHOD NAME="payments" PARAMETERS="k" POSSIBLEACTIONS1="k" MAINTAINSESSION="k" RESPONSE="k" NEXTLEVEL="k"></METHOD>
              <METHOD NAME="payments" PARAMETERS="L" POSSIBLEACTIONS1="L" MAINTAINSESSION="L" RESPONSE="L" NEXTLEVEL="L"></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>
          <FAILUREREGION INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="LOWBALANCE">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="1" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="SETPSOFAILED">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="2" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="UCIPDEBIT">
              <METHOD NAME="UNSETPSOINMINSAT" PARAMETERS="SLN7" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_UNSETPSO_FALSE" MAINTAINSESSION="NO" RESPONSE="-6" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="3" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="UNSETPSO">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="4" NEXTLEVEL="" />
            </INPUT>
          </FAILUREREGION>
        </STATEINFORMATION>
        <STATEINFORMATION TYPE="POSTPAID">
          <INIT INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="SLN7DEACTIVATION">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="5" NEXTLEVEL="" />
            </INPUT>
          </INIT>
        </STATEINFORMATION>
      </NI>
    </MODES>
  </AP>
  <TN>
    <MODES>
      <NI>
        <STATEINFORMATION TYPE="PREPAID">
          <INIT INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="LPC16ACTIVATION">
              <METHOD NAME="SETPSOINUCIP" PARAMETERS="LPC16" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LP26ACTIVATION">
              <METHOD NAME="SETPSOINUCIP" PARAMETERS="LP26" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LP49ACTIVATION">
              <METHOD NAME="SETPSOINUCIP" PARAMETERS="LP49" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LPT16ACTIVATION">
              <METHOD NAME="SETPSOINUCIP" PARAMETERS="LPT16" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LP60ACTIVATION">
              <METHOD NAME="SETPSOINUCIP" PARAMETERS="LP60" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LPC16DEACTIVATION">
              <METHOD NAME="UNSETPSOINUCIP" PARAMETERS="LPC16" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LP26DEACTIVATION">
              <METHOD NAME="UNSETPSOINUCIP" PARAMETERS="LP26" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <!--<METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />-->
            </INPUT>
            <INPUT VALUE="LP49DEACTIVATION">
              <METHOD NAME="UNSETPSOINUCIP" PARAMETERS="LP49" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LPT16DEACTIVATION">
              <METHOD NAME="UNSETPSOINUCIP" PARAMETERS="LPT16" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LP60DEACTIVATION">
              <METHOD NAME="UNSETPSOINUCIP" PARAMETERS="LP60" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
          </INIT>
          <FAILUREREGION INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="LOWBALANCE">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="1" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="SETPSOFAILED">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="2" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="UCIPDEBIT">
              <METHOD NAME="UNSETPSOINMINSAT" PARAMETERS="SLN7" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_UNSETPSO_FALSE" MAINTAINSESSION="NO" RESPONSE="-6" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="3" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="UNSETPSO">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="4" NEXTLEVEL="" />
            </INPUT>
          </FAILUREREGION>
        </STATEINFORMATION>
        <STATEINFORMATION TYPE="POSTPAID">
          <INIT INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="5" NEXTLEVEL="" />
            </INPUT>
          </INIT>
        </STATEINFORMATION>
      </NI>
    </MODES>
  </TN>
  <KER>
    <MODES>
      <NI>
        <STATEINFORMATION TYPE="PREPAID">
          <INIT INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="LP6ACTIVATION">
              <METHOD NAME="SETPSOINUCIP" PARAMETERS="LP6" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LPSP15ACTIVATION">
              <METHOD NAME="SETPSOINUCIP" PARAMETERS="LPSP15" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LP6DEACTIVATION">
              <METHOD NAME="UNSETPSOINUCIP" PARAMETERS="LP6" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LPSP15DEACTIVATION">
              <METHOD NAME="UNSETPSOINUCIP" PARAMETERS="LPSP15" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="LP6SUBSCRIPTION">
              <METHOD NAME="CHECKSUBSCRIBERBALANCE" PARAMETERS="LP6" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_LOWBALANCE_INSUFFICIENTBALANCE" MAINTAINSESSION="NO" RESPONSE="-3" NEXTLEVEL="" />
              <METHOD NAME="SETPSOINUCIP" PARAMETERS="LP6" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="FIREUCIPDEBIT" PARAMETERS="LP6" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_CHARGINGFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="0" NEXTLEVEL="" />
            </INPUT>
          </INIT>
          <FAILUREREGION INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="LOWBALANCE">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="1" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="CHARGINGFAILED">
              <METHOD NAME="UNSETPSOINUCIP" PARAMETERS="LP6" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_SETPSOFAILED_FALSE" MAINTAINSESSION="NO" RESPONSE="-4" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="6" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="SETPSOFAILED">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="2" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="UCIPDEBIT">
              <METHOD NAME="UNSETPSOINMINSAT" PARAMETERS="SLN7" POSSIBLEACTIONS="FALLOUTON_FAILUREREGION_UNSETPSO_FALSE" MAINTAINSESSION="NO" RESPONSE="-6" NEXTLEVEL="" />
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="3" NEXTLEVEL="" />
            </INPUT>
            <INPUT VALUE="UNSETPSO">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="4" NEXTLEVEL="" />
            </INPUT>
          </FAILUREREGION>
        </STATEINFORMATION>
        <STATEINFORMATION TYPE="POSTPAID">
          <INIT INVALIDINPUTRESPONSE="-2">
            <INPUT VALUE="">
              <METHOD NAME="SENDMESSAGE" PARAMETERS="" POSSIBLEACTIONS="FALLOUTONSUCCESS" MAINTAINSESSION="NO" RESPONSE="5" NEXTLEVEL="" />
            </INPUT>
          </INIT>
        </STATEINFORMATION>
      </NI>
    </MODES>
  </KER>
</SESSIONANALYSER>

Upvotes: 4

Views: 312

Answers (2)

Dimitre Novatchev
Dimitre Novatchev

Reputation: 243539

The XPath expression you are evaluating:

//SESSIONANALYSER/KER/MODES/NI/STATEINFORMATION[@TYPE='PREPAID']/INIT/INPUT

selects not just one but six INPUT elements.

You specified that you want to add a new element after the first of these.

Therefore, use this XPath expression, which selects exactly one (the wanted) INPUT element:

(//SESSIONANALYSER/KER/MODES/NI/STATEINFORMATION[@TYPE='PREPAID']/INIT/INPUT)[1]

Most XPath engines provide a SelectNodes() method that returns the selected nodes in a NodeList and the programmer needs to iterate through this collection -- even when only a single node was selected -- bear this in mind.

Upvotes: 2

MattH
MattH

Reputation: 38245

I'm not sure why you have BH in your xpath.

This xpath query select just one element from your sample and I think it's the one that you want:

/SESSIONANALYSER/KER/MODES/NI/STATEINFORMATION[@TYPE='PREPAID']
    /INIT[@INVALIDINPUTRESPONSE='-2']
    /INPUT[@VALUE='LP6ACTIVATION']

Upvotes: 1

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