[ACCEPTED]-Case insensitive XML parser in c#-xpath

An XMl document can have two different elements named respectively: MyName and myName -- that are intended to be different. Converting/treating them as the same name is an error that can have gross consequences.

In case the above is not the case, then 7 here is a more precise solution, using XSLT 6 to process the document into one that only 5 has lowercase element names and lowercase 4 attribute names:

<xsl:stylesheet version="1.0"
 xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
 <xsl:output omit-xml-declaration="yes" indent="yes"/>
 <xsl:strip-space elements="*"/>

 <xsl:variable name="vUpper" select=
 "'ABCDEFGHIJKLMNOPQRSTUVWXYZ'"/>

 <xsl:variable name="vLower" select=
 "'abcdefghijklmnopqrstuvwxyz'"/>

 <xsl:template match="node()|@*">
     <xsl:copy>
       <xsl:apply-templates select="node()|@*"/>
     </xsl:copy>
 </xsl:template>

 <xsl:template match="*[name()=local-name()]" priority="2">
  <xsl:element name="{translate(name(), $vUpper, $vLower)}"
   namespace="{namespace-uri()}">
       <xsl:apply-templates select="node()|@*"/>
  </xsl:element>
 </xsl:template>

 <xsl:template match="*" priority="1">
  <xsl:element name=
   "{substring-before(name(), ':')}:{translate(local-name(), $vUpper, $vLower)}"
   namespace="{namespace-uri()}">
       <xsl:apply-templates select="node()|@*"/>
  </xsl:element>
 </xsl:template>

 <xsl:template match="@*[name()=local-name()]" priority="2">
  <xsl:attribute name="{translate(name(), $vUpper, $vLower)}"
   namespace="{namespace-uri()}">
       <xsl:value-of select="."/>
  </xsl:attribute>
 </xsl:template>

 <xsl:template match="@*" priority="1">
  <xsl:attribute name=
   "{substring-before(name(), ':')}:{translate(local-name(), $vUpper, $vLower)}"
   namespace="{namespace-uri()}">
     <xsl:value-of select="."/>
  </xsl:attribute>
 </xsl:template>
</xsl:stylesheet>

when this transformation is applied on any XML document, for example this one:

<authors xmlns:user="myNamespace">
  <?ttt This is a PI ?>
  <Author xmlns:user2="myNamespace2">
    <Name idd="VH">Victor Hugo</Name>
    <user2:Name idd="VH">Victor Hugo</user2:Name>
    <Nationality xmlns:user3="myNamespace3">French</Nationality>
  </Author>
  <!-- This is a very long comment the purpose is
       to test the default stylesheet for long comments-->
  <Author Period="classical">
    <Name>Sophocles</Name>
    <Nationality>Greek</Nationality>
  </Author>
  <author>
    <Name>Leo Tolstoy</Name>
    <Nationality>Russian</Nationality>
  </author>
  <Author>
    <Name>Alexander Pushkin</Name>
    <Nationality>Russian</Nationality>
  </Author>
  <Author Period="classical">
    <Name>Plato</Name>
    <Nationality>Greek</Nationality>
  </Author>
</authors>

the wanted, correct result (element and attribute names converted to lowercase) is produced:

<authors><?ttt This is a PI ?>
   <author>
      <name idd="VH">Victor Hugo</name>
      <user2:name xmlns:user2="myNamespace2" idd="VH">Victor Hugo</user2:name>
      <nationality>French</nationality>
   </author><!-- This is a very long comment the purpose is
       to test the default stylesheet for long comments-->
   <author period="classical">
      <name>Sophocles</name>
      <nationality>Greek</nationality>
   </author>
   <author>
      <name>Leo Tolstoy</name>
      <nationality>Russian</nationality>
   </author>
   <author>
      <name>Alexander Pushkin</name>
      <nationality>Russian</nationality>
   </author>
   <author period="classical">
      <name>Plato</name>
      <nationality>Greek</nationality>
   </author>
</authors>

Once the document is converted 3 to your desired form, then you can perform 2 any desired processing on the converted 1 document.

You can create case-insensitive methods 1 (extensions for usability), e.g.:

public static class XDocumentExtensions
{
    public static IEnumerable<XElement> ElementsCaseInsensitive(this XContainer source,  
        XName name)
    {
        return source.Elements()
            .Where(e => e.Name.Namespace == name.Namespace 
                && e.Name.LocalName.Equals(name.LocalName, StringComparison.OrdinalIgnoreCase));
    }
}

XML is text. Just ToLower it before loading to 6 whatever parser you are using.

So long as 5 you don't have to validate against a schema 4 and don't mind the values being all lower 3 case, this should work just fine.

The fact 2 is that any XML parser will be case sensitive. If 1 it were not, it wouldn't be an XML parser.

I use another solution. The reason people 10 want this is because you don't want to duplicate 9 the name of the property in the class file 8 in an attribute as well. So what I do is 7 add a custom attribute to all properties:

[AttributeUsage(AttributeTargets.Property)]
public class UsePropertyNameToLowerAsXmlElementAttribute: XmlElementAttribute
{
    public UsePropertyNameToLowerAsXmlElementAttribute([CallerMemberName] string propertyName = null)
    : base(propertyName?.ToLower())
    {
    }
}

This 6 way the XML serializer can map lower case 5 properties to CamelCased classes.

The properties 4 on the classes still have a decorator that 3 says that something is different, but you 2 don't have the overhead of marking every 1 property with a name:

public class Settings
{
    [UsePropertyNameToLowerAsXmlElement]
    public string VersionId { get; set; }

    [UsePropertyNameToLowerAsXmlElement]
    public int? ApplicationId { get; set; }
}

I would start by converting all tags and 2 attribute names to lowercase, leaving values 1 untouched, by using SAX parsing, ie. with XmlTextReader.