c# - Adding read elements without xmlns definition on each element - Stack Overflow

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I'm trying to pull data out of a file in order to split it. I need the Data element, the Header, Reference and Sender that is being used for each splitted file, which will contain these elements plus one Item element per file.

<Data xmlns=";>
    <Header>
        <Contact>
            <Id>MS0199</Id>
        </Contact>
        <ContactRef>GA</ContactRef>
    </Header>
    <Reference>RA0122</Reference>
    <Sender>
        <SubNo>19223</SubNo>
    </Sender>
    <Item id="TA001">
        <Code>IAT-0100</Code>
    </Item>
    <Item id="TA054">
        <Code>MFF-2910</Code>
    </Item> 
</Data>

I'm extracting the "Header data" (Data, Header, Reference, Sender) by this:

        using (XmlReader reader = XmlReader.Create(xmlFile))
        {
            reader.MoveToContent();

            while (reader.Read())
            {
                if (reader.NodeType == XmlNodeType.Element && reader.Name == "Header")
                {
                    hdrval = XElement.Load(reader.ReadSubtree());
                }
                if (reader.NodeType == XmlNodeType.Element && reader.Name == "Reference")
                {
                    refval = XElement.Load(reader.ReadSubtree());
                }
                if (reader.NodeType == XmlNodeType.Element && reader.Name == "Sender")
                {
                    sndval = XElement.Load(reader.ReadSubtree());
                }
                if (reader.NodeType == XmlNodeType.Element && reader.Name == "Item")
                {
                    break;
                }
            }
        }

        XNamespace ns = ";;
        XElement Header = new(ns + "Data",
            hdrval,
            refval,
            sndval,
        );

Problem is that when I look at the resulting output it now says:

<Data xmlns=";>
    <Header xmlns=";>
        <Contact>
            <Id>MS0199</Id>
        </Contact>
        <ContactRef>GA</ContactRef>
    </Header>
    <Reference xmlns=";>RA0122</Reference>
    <Sender xmlns=";>
        <SubNo>19223</SubNo>
    </Sender>
</Data>

Is there a way to stop it from injecting the xmlns definition on every single child I pull out? I want it on the Data element seeing as it's the root element but not on every single child.

It works if I use LINQ with XElement, however the file can be multiple GB's in size so I'm trying to use the XmlReader in order to stream the file rather than loading the whole thing at once.

I'm trying to pull data out of a file in order to split it. I need the Data element, the Header, Reference and Sender that is being used for each splitted file, which will contain these elements plus one Item element per file.

<Data xmlns="http://foo.schema">
    <Header>
        <Contact>
            <Id>MS0199</Id>
        </Contact>
        <ContactRef>GA</ContactRef>
    </Header>
    <Reference>RA0122</Reference>
    <Sender>
        <SubNo>19223</SubNo>
    </Sender>
    <Item id="TA001">
        <Code>IAT-0100</Code>
    </Item>
    <Item id="TA054">
        <Code>MFF-2910</Code>
    </Item> 
</Data>

I'm extracting the "Header data" (Data, Header, Reference, Sender) by this:

        using (XmlReader reader = XmlReader.Create(xmlFile))
        {
            reader.MoveToContent();

            while (reader.Read())
            {
                if (reader.NodeType == XmlNodeType.Element && reader.Name == "Header")
                {
                    hdrval = XElement.Load(reader.ReadSubtree());
                }
                if (reader.NodeType == XmlNodeType.Element && reader.Name == "Reference")
                {
                    refval = XElement.Load(reader.ReadSubtree());
                }
                if (reader.NodeType == XmlNodeType.Element && reader.Name == "Sender")
                {
                    sndval = XElement.Load(reader.ReadSubtree());
                }
                if (reader.NodeType == XmlNodeType.Element && reader.Name == "Item")
                {
                    break;
                }
            }
        }

        XNamespace ns = "http://foo.schema";
        XElement Header = new(ns + "Data",
            hdrval,
            refval,
            sndval,
        );

Problem is that when I look at the resulting output it now says:

<Data xmlns="http://foo.schema">
    <Header xmlns="http://foo.schema">
        <Contact>
            <Id>MS0199</Id>
        </Contact>
        <ContactRef>GA</ContactRef>
    </Header>
    <Reference xmlns="http://foo.schema">RA0122</Reference>
    <Sender xmlns="http://foo.schema">
        <SubNo>19223</SubNo>
    </Sender>
</Data>

Is there a way to stop it from injecting the xmlns definition on every single child I pull out? I want it on the Data element seeing as it's the root element but not on every single child.

It works if I use LINQ with XElement, however the file can be multiple GB's in size so I'm trying to use the XmlReader in order to stream the file rather than loading the whole thing at once.

• c#
• xml
• xml-parsing
• linq-to-xml

Share Improve this question Follow edited Feb 19 at 18:13 dbc 117k2626 gold badges264264 silver badges387387 bronze badges asked Feb 19 at 17:41 JaggenSWEJaggenSWE 2,10622 gold badges2525 silver badges4444 bronze badges 4

• Yes. The namespace definition only has to be on a parent node. Normally adding the definition on the root element is sufficent. – jdweng Commented Feb 19 at 17:56
• Yes, but in this case it automatically adds it to every single child. That's the problem :) – JaggenSWE Commented Feb 19 at 18:00
• It's not adding it, it's already there at XElement.Load. You need to remove it, see stackoverflow/questions/40517306/… – Charlieface Commented Feb 19 at 18:02
• There is nothing wrong with having the definition on every element except it creates a larger file. The real answer is to use XmlReader to read the huge xml file. See my answer here (last answer) to see how to read a huge xml file using Xmlreader : stackoverflow/questions/49139691/… – jdweng Commented Feb 19 at 22:18

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1 Answer 1

Sorted by: Reset to default 3

Your problem is that ReadSubtree() reads the current node as if it were the root of its own well-formed XML document. Therefore it inserts a namespace attribute corresponding to the namespace of the current element unless one is there already.

If you don't want that, avoid ReadSubtree() and call XNode.ReadFrom() directly:

using (var reader = XmlReader.Create(xmlFile, new XmlReaderSettings { IgnoreWhitespace = true } ))
{
    reader.MoveToContent();

    while (!reader.EOF)
    {
        if (reader.NodeType == XmlNodeType.Element && reader.Name == "Header")
        {
            hdrval = (XElement)XNode.ReadFrom(reader);
            // ReadFrom() leaves the reader positioned AFTER the end element, so no nead for an additional Read()
        }
        else if (reader.NodeType == XmlNodeType.Element && reader.Name == "Reference")
        {
            refval = (XElement)XNode.ReadFrom(reader);
        }
        else if (reader.NodeType == XmlNodeType.Element && reader.Name == "Sender")
        {
            sndval = (XElement)XNode.ReadFrom(reader);
        }
        else if (reader.NodeType == XmlNodeType.Element && reader.Name == "Item")
        {
            break; // Stop reading at the first <Item id="xxx"> node
        }
        else
        {
            reader.Read();
        }
    }
}

Notes:

• ReadSubtree() leaves the reader positioned on the EndElement tag, but ReadFrom() leaves it positioned immediately after the EndElement tag. Thus switching from one to another requires rewriting your loop logic slightly, as unconditionally reading the next node may end up skipping some content.

• When you do use ReadSubtree(), you should take note of the following documentation remark:

  You should not perform any operations on the original reader until the new reader has been closed. This action is not supported and can result in unpredictable behavior.

  e.g.

  using (var subReader = reader.ReadSubtree())
      hdrval = XElement.Load(subReader);
  

• I've noticed that XNode.ReadFrom(reader) is loading the insignificant whitespace from your input XML as text nodes in your XElement hierarchy. If you don't want that, create your XmlReader with XmlReaderSettings.IgnoreWhitespace = true:

  Gets or sets a value indicating whether to ignore insignificant white space.

  e.g.:

  using (var reader = XmlReader.Create(
      xmlFile, 
      new XmlReaderSettings { IgnoreWhitespace = true } ))
  {
  

Demo fiddle here.

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