pineapples has asked for the wisdom of the Perl Monks concerning the following question:

Perl MONKs, I am trying to use Perl and Lib::XML to conditionally replace XML tags but to preserve the order of the XML input file(which is why I cannot use XML:Simple) Consider the following XML 
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE POWERMART SYSTEM "powrmart.dtd">
<POWERMART CREATION_DATE="10/19/2010 07:15:27" REPOSITORY_VERSION="179
+.88">
<REPOSITORY NAME="IT_REP" VERSION="179" CODEPAGE="Latin1" DATABASETYPE
+="DB2">
<FOLDER NAME="CADM" GROUP="" OWNER="Administrator" SHARED="NOTSHARED" 
+DESCRIPTION="" PERMISSIONS="rwx---r-x" UUID="ad49ad64-d86a-4823-9c04-
+2d881fe79240">
    <MAPPING DESCRIPTION ="" ISVALID ="YES" NAME ="m_EQ_Hist_Alloc_Att
+rib_build" OBJECTVERSION ="1" VERSIONNUMBER ="1">
        <TRANSFORMATION DESCRIPTION ="" NAME ="expr_seq_alloc_attrib_i
+d_RPT" OBJECTVERSION ="1" REUSABLE ="NO" TYPE ="Expression" VERSIONNU
+MBER ="1">
            <TRANSFORMFIELD DATATYPE ="bigint" DEFAULTVALUE ="" DESCRI
+PTION ="" NAME ="NEXTVAL" PICTURETEXT ="" PORTTYPE ="INPUT" PRECISION
+ ="19" SCALE ="0"/>
            <TRANSFORMFIELD DATATYPE ="bigint" DEFAULTVALUE ="" DESCRI
+PTION ="" EXPRESSION ="IIF(SEQ_START_VAL= 0, (IIF(ISNULL(:LKP.LKP_T_A
+lloc_Attrib_Seq(1)), 0, :LKP.LKP_T_Alloc_Attrib_Seq(1))), SEQ_START_V
+AL)" EXPRESSIONTYPE ="GENERAL" NAME ="SEQ_START_VAL" PICTURETEXT ="" 
+PORTTYPE ="LOCAL VARIABLE" PRECISION ="19" SCALE ="0"/>
            <TRANSFORMFIELD DATATYPE ="bigint" DEFAULTVALUE ="ERROR(&a
+pos;transformation error&apos;)" DESCRIPTION ="" EXPRESSION ="SEQ_STA
+RT_VAL+NEXTVAL" EXPRESSIONTYPE ="GENERAL" NAME ="OUT_NEXTVAL" PICTURE
+TEXT ="" PORTTYPE ="OUTPUT" PRECISION ="19" SCALE ="0"/>
            <TABLEATTRIBUTE NAME ="Tracing Level" VALUE ="Normal"/>
            <METADATAEXTENSION DATATYPE ="STRING" DESCRIPTION ="" DOMA
+INNAME ="User Defined Metadata Domain" ISCLIENTEDITABLE ="YES" ISCLIE
+NTVISIBLE ="YES" ISREUSABLE ="NO" ISSHAREREAD ="NO" ISSHAREWRITE ="NO
+" MAXLENGTH ="256" NAME ="Blank" VALUE ="&apos;&apos;" VENDORNAME ="I
+NFORMATICA"/>
        </TRANSFORMATION>
        <TRANSFORMATION DESCRIPTION ="" NAME ="expr_seq_alloc_attrib_i
+d_REV_HIST" OBJECTVERSION ="1" REUSABLE ="NO" TYPE ="Sequence" VERSIO
+NNUMBER ="1">
            <TRANSFORMFIELD DATATYPE ="bigint" DEFAULTVALUE ="" DESCRI
+PTION ="" NAME ="NEXTVAL" PICTURETEXT ="" PORTTYPE ="INPUT" PRECISION
+ ="19" SCALE ="0"/>
            <TRANSFORMFIELD DATATYPE ="bigint" DEFAULTVALUE ="" DESCRI
+PTION ="" EXPRESSION ="IIF(SEQ_START_VAL= 0, (IIF(ISNULL(:LKP.LKP_T_A
+lloc_Attrib_Seq(1)), 0, :LKP.LKP_T_Alloc_Attrib_Seq(1))), SEQ_START_V
+AL)" EXPRESSIONTYPE ="GENERAL" NAME ="SEQ_START_VAL" PICTURETEXT ="" 
+PORTTYPE ="LOCAL VARIABLE" PRECISION ="19" SCALE ="0"/>
            <TRANSFORMFIELD DATATYPE ="bigint" DEFAULTVALUE ="ERROR(&a
+pos;transformation error&apos;)" DESCRIPTION ="" EXPRESSION ="SEQ_STA
+RT_VAL+NEXTVAL" EXPRESSIONTYPE ="GENERAL" NAME ="OUT_NEXTVAL" PICTURE
+TEXT ="" PORTTYPE ="OUTPUT" PRECISION ="19" SCALE ="0"/>
            <TABLEATTRIBUTE NAME ="Tracing Level" VALUE ="Normal"/>
            <METADATAEXTENSION DATATYPE ="STRING" DESCRIPTION ="" DOMA
+INNAME ="User Defined Metadata Domain" ISCLIENTEDITABLE ="YES" ISCLIE
+NTVISIBLE ="YES" ISREUSABLE ="NO" ISSHAREREAD ="NO" ISSHAREWRITE ="NO
+" MAXLENGTH ="256" NAME ="Blank" VALUE ="&apos;&apos;" VENDORNAME ="I
+NFORMATICA"/>
        </TRANSFORMATION>
</MAPPING>
</FOLDER>
</REPOSITORY>
</POWERMART>

[download]
I want to change the transformations where the TYPE ="Sequence" and change all DATATYPES in those transformations to "integer" ie the second set of transformation tags. So the above XML should be :- 
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE POWERMART SYSTEM "powrmart.dtd">
<POWERMART CREATION_DATE="10/19/2010 07:15:27" REPOSITORY_VERSION="179
+.88">
<REPOSITORY NAME="IT_REP" VERSION="179" CODEPAGE="Latin1" DATABASETYPE
+="DB2">
<FOLDER NAME="CADM" GROUP="" OWNER="Administrator" SHARED="NOTSHARED" 
+DESCRIPTION="" PERMISSIONS="rwx---r-x" UUID="ad49ad64-d86a-4823-9c04-
+2d881fe79240">
    <MAPPING DESCRIPTION ="" ISVALID ="YES" NAME ="m_EQ_Hist_Alloc_Att
+rib_build" OBJECTVERSION ="1" VERSIONNUMBER ="1">
        <TRANSFORMATION DESCRIPTION ="" NAME ="expr_seq_alloc_attrib_i
+d_RPT" OBJECTVERSION ="1" REUSABLE ="NO" TYPE ="Expression" VERSIONNU
+MBER ="1">
            <TRANSFORMFIELD DATATYPE ="bigint" DEFAULTVALUE ="" DESCRI
+PTION ="" NAME ="NEXTVAL" PICTURETEXT ="" PORTTYPE ="INPUT" PRECISION
+ ="19" SCALE ="0"/>
            <TRANSFORMFIELD DATATYPE ="bigint" DEFAULTVALUE ="" DESCRI
+PTION ="" EXPRESSION ="IIF(SEQ_START_VAL= 0, (IIF(ISNULL(:LKP.LKP_T_A
+lloc_Attrib_Seq(1)), 0, :LKP.LKP_T_Alloc_Attrib_Seq(1))), SEQ_START_V
+AL)" EXPRESSIONTYPE ="GENERAL" NAME ="SEQ_START_VAL" PICTURETEXT ="" 
+PORTTYPE ="LOCAL VARIABLE" PRECISION ="19" SCALE ="0"/>
            <TRANSFORMFIELD DATATYPE ="bigint" DEFAULTVALUE ="ERROR(&a
+pos;transformation error&apos;)" DESCRIPTION ="" EXPRESSION ="SEQ_STA
+RT_VAL+NEXTVAL" EXPRESSIONTYPE ="GENERAL" NAME ="OUT_NEXTVAL" PICTURE
+TEXT ="" PORTTYPE ="OUTPUT" PRECISION ="19" SCALE ="0"/>
            <TABLEATTRIBUTE NAME ="Tracing Level" VALUE ="Normal"/>
            <METADATAEXTENSION DATATYPE ="STRING" DESCRIPTION ="" DOMA
+INNAME ="User Defined Metadata Domain" ISCLIENTEDITABLE ="YES" ISCLIE
+NTVISIBLE ="YES" ISREUSABLE ="NO" ISSHAREREAD ="NO" ISSHAREWRITE ="NO
+" MAXLENGTH ="256" NAME ="Blank" VALUE ="&apos;&apos;" VENDORNAME ="I
+NFORMATICA"/>
        </TRANSFORMATION>
        <TRANSFORMATION DESCRIPTION ="" NAME ="expr_seq_alloc_attrib_i
+d_REV_HIST" OBJECTVERSION ="1" REUSABLE ="NO" TYPE ="Sequence" VERSIO
+NNUMBER ="1">
            <TRANSFORMFIELD DATATYPE ="integer" DEFAULTVALUE ="" DESCR
+IPTION ="" NAME ="NEXTVAL" PICTURETEXT ="" PORTTYPE ="INPUT" PRECISIO
+N ="19" SCALE ="0"/>
            <TRANSFORMFIELD DATATYPE ="integer" DEFAULTVALUE ="" DESCR
+IPTION ="" EXPRESSION ="IIF(SEQ_START_VAL= 0, (IIF(ISNULL(:LKP.LKP_T_
+Alloc_Attrib_Seq(1)), 0, :LKP.LKP_T_Alloc_Attrib_Seq(1))), SEQ_START_
+VAL)" EXPRESSIONTYPE ="GENERAL" NAME ="SEQ_START_VAL" PICTURETEXT =""
+ PORTTYPE ="LOCAL VARIABLE" PRECISION ="19" SCALE ="0"/>
            <TRANSFORMFIELD DATATYPE ="integer" DEFAULTVALUE ="ERROR(&
+apos;transformation error&apos;)" DESCRIPTION ="" EXPRESSION ="SEQ_ST
+ART_VAL+NEXTVAL" EXPRESSIONTYPE ="GENERAL" NAME ="OUT_NEXTVAL" PICTUR
+ETEXT ="" PORTTYPE ="OUTPUT" PRECISION ="19" SCALE ="0"/>
            <TABLEATTRIBUTE NAME ="Tracing Level" VALUE ="Normal"/>
            <METADATAEXTENSION DATATYPE ="STRING" DESCRIPTION ="" DOMA
+INNAME ="User Defined Metadata Domain" ISCLIENTEDITABLE ="YES" ISCLIE
+NTVISIBLE ="YES" ISREUSABLE ="NO" ISSHAREREAD ="NO" ISSHAREWRITE ="NO
+" MAXLENGTH ="256" NAME ="Blank" VALUE ="&apos;&apos;" VENDORNAME ="I
+NFORMATICA"/>
        </TRANSFORMATION>
</MAPPING>
</FOLDER>
</REPOSITORY>
</POWERMART>

[download]
I came up with this code below. I seem to be able to identify the Transformation Type, but after that I cannot seem to identify the child nodes to identify the datatype. I am a beginner to Perl so any help would be greatly achieved, even if it looks obvious. Thank you very much! 
 my $parser = XML::LibXML->new();
  my $tree = $parser->parse_file($inputfile);
  my $root = $tree->getDocumentElement;
  my $sequence = 'Sequence';        
      
  my $querysequence = '//REPOSITORY/FOLDER/MAPPING/TRANSFORMATION/@TYP
+E';

my @typenodes = $root->findnodes($querysequence);
   
 foreach my $sequencetransform (@typenodes) {
       my $literal = $sequencetransform->to_literal;
        #print $literal;
        if ( $literal == 'Sequence' ) {
              print $literal;
        my @datatypenodes = $sequencetransform->findnodes('TRANSFORMFI
+ELD/@DATATYPE');
           foreach my $sequencetransform_data (@datatypenodes) {
        print "am i here?";
        print Dumper $sequencetransform->findnodes('TRANSFORMFIELD/@DA
+TATYPE');
           #my $literal1 = $sequencetransform_data->to_literal;
        print $literal1;
             if ( $literal1 == 'bigint' ) { 
                $sequencetransform_data->setValue('integer'); 

                   }
            }    
     }
 }

[download]

Replies are listed 'Best First'.
Re: Perl and Lib::XML usage
by ikegami (Patriarch) on Oct 25, 2010 at 21:43 UTC

    You are searching for a subset of 

    .../MAPPING/TRANSFORMATION/@TYPE/TRANSFORMFIELD/@TYPE

    [download]

    An attribute cannot have a child element, so that can't possibly match. Solution: 

    for ($root->findnodes(
    '/POWERMART/REPOSITORY/FOLDER/MAPPING' .
    '/TRANSFORMATION[@TYPE="Sequence"]' .
    '/TRANSFORMFIELD[@TYPE="bigint"]'
)) {
    $_->setAttribute('TYPE', 'integer');
}

    [download]

    Square brackets specify which nodes to filter through, like a SELECT clause in SQL.

[reply]
[d/l]
[select]
      Thanks a bunch Perl Monks. This particular solution work a treat. But thanks to all who contributed, each one of you had valid comments that I can learn from.
[reply]
Re: Perl and Lib::XML usage
by chromatic (Archbishop) on Oct 26, 2010 at 06:50 UTC
    if ( $literal == 'Sequence' )

    String equality (eq) will work much better.

[reply]
[d/l]
      Just want to add a line. The expression if ( $literal == 'Sequence' ) will always return true if $literal can not be converted to a numeric value. Both the operands will be converted to 0 (due to '==' operator) and a warning will be given if use warnings is used.
[reply]
[d/l]
[select]
Re: Perl and Lib::XML usage
by NetWallah (Canon) on Oct 25, 2010 at 19:48 UTC
    Your XML tag: 
     <MAPPING DESCRIPTION ="" ISVALID ="YES" NAME ="m_EQ_Hist_Alloc_Attrib
+_build" OBJECTVERSION ="1" VERSIONNUMBER ="1">

    [download]
    seems not to be closed. Here is the error I get: 
    Entity: line 21: parser error : Opening and ending tag mismatch: MAPPI
+NG line 0 and FOLDER
</FOLDER>
         ^ at libxmltest.pl line ...

    [download]

         Syntactic sugar causes cancer of the semicolon.        --Alan Perlis

[reply]
[d/l]
[select]
      Apologies I have updated the XML
[reply]
Re: Perl and Lib::XML usage
by choroba (Cardinal) on Oct 26, 2010 at 08:17 UTC
    Things get much simpler when using XML::XSH2. In fact, you would just need:
    open 867322.xml ;
for /POWERMART/REPOSITORY/FOLDER/MAPPING/TRANSFORMATION[@TYPE="Sequenc
+e"]/TRANSFORMFIELD set @DATATYPE "integer" ;
save :b ;

    [download]
[reply]
[d/l]
Re: Perl and Lib::XML usage
by aquarium (Curate) on Oct 25, 2010 at 23:09 UTC
    almost feels like dusting off a xsl processor to do this, instead of perl code.
    the hardest line to type correctly is: stty erase ^H
[reply]

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