Whixh XML Parser to use?

Question

Whixh XML Parser to use?

Peter Volz 1,295

Hello all

According to this post:

https://stackoverflow.com/questions/15136264/how-can-i-say-a-file-is-svg-without-using-a-magic-number

To detect if a file is xml or svg , check for initial <?xml will not work, sometimes, xml documents won't start with that preamble, best way is to use a real XML parser to test that the file is well-formed XML that contains the svg top-level element, however, the given code is Phyton which I don't understand at all:

Anyone knows the best .NET xml parser to use and how to achieve the similar function?

Thanks indeed :)

Hui Liu-MSFT 48,676 Microsoft External Staff

Hi,@Peter Volz.Welcome Microsoft Q&A.

In the .NET framework, the best XML parser to detect if a file is XML or SVG is the XmlReader class.

Here's an example of how you can use XmlReader to determine if a file is XML or SVG. You could try to refer to it.

using System.Xml;

public bool IsXmlOrSvgFile(string filePath)
{
    try
    {
        using (XmlReader reader = XmlReader.Create(filePath))
        {
            while (reader.Read())
            {
                if (reader.NodeType == XmlNodeType.Element && (reader.Name == "svg" || reader.Name == "svg:svg"))
                {
                    return true; // File is SVG
                }
            }
        }
        
        return true; // File is XML (no SVG element found)
    }
    catch (XmlException)
    {
        return false; // File is not well-formed XML
    }
}

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Peter Volz 1,295 Reputation points

2023-06-15T00:19:03.1233333+00:00

Hello, thanks, seems not working on these SVG files:

https://dev.w3.org/SVG/tools/svgweb/samples/svg-files/anim1.svg
Castorix31 90,681 Reputation points

2023-06-15T08:22:07.0266667+00:00

ID2D1DeviceContext5::CreateSvgDocument can be used to check a .SVG, but it is a bit a sledgehammer to crack a nut...

Hui Liu-MSFT 48,676 Microsoft External Staff

Hi,@Peter Volz. Does the following code meet your needs? If not, could you share me a minimal example containing svg files and steps that can reproduce the problem to reproduce the problem and analyze it?

 public void f(string filePath)
        {
       

            bool isSvgFile = string.Equals(System.IO.Path.GetExtension(filePath), ".svg", StringComparison.OrdinalIgnoreCase);

            if (isSvgFile)
            {
                MessageBox.Show("The file is an SVG file.");
            }
            else
            {
                MessageBox.Show("The file is not an SVG file.");
            }
        }

Peter Volz 1,295 Reputation points

2023-06-15T11:18:06.4166667+00:00

Thanks, not extension based, however, the exception was DTD prohibited related, seems that:

XmlReaderSettings.DtdProcessing > Ignore or Parse

will solve the problem, which one do you recommend? Ignore or Parse

and for XmlReaderSettings, do you have any suggestion to alter the default values to validate general XMLs and distinguish svg? :)
Dewayne Basnett 1,381 Reputation points

2023-06-15T14:17:29.2833333+00:00
If you have a svg file it can be read with XElement regardless of the presence of the xml declaration

<?xml version
Hui Liu-MSFT 48,676 Reputation points Microsoft External Staff

2023-06-16T02:30:14.69+00:00

Hi,@Peter Volz.The appropriate choice depends on your specific requirements and the level of DTD validation you need.

XmlReaderSettings.DtdProcessing.Ignore: This option ignores the DTD completely. It allows parsing the XML without performing DTD validation. If you are not concerned about DTD validation and just want to extract the data from the XML, this option can be sufficient. It avoids potential exceptions related to DTD usage.

XmlReaderSettings.DtdProcessing.Parse: This option enables DTD processing and performs DTD validation during parsing. It ensures that the XML adheres to the DTD rules. If you require DTD validation and want to ensure that the XML complies with the specified DTD, you cOULD choose this option. And note that enabling this option can introduce potential security risks if the XML contains untrusted or malicious external entities.

3 answers

Your answer

Hui Liu-MSFT 48,676 Reputation points Microsoft External Staff

2023-06-12T02:09:10.0833333+00:00

Hi,@Peter Volz.Welcome Microsoft Q&A.

In the .NET framework, the best XML parser to detect if a file is XML or SVG is the XmlReader class.

Here's an example of how you can use XmlReader to determine if a file is XML or SVG. You could try to refer to it.

using System.Xml; public bool IsXmlOrSvgFile(string filePath) { try { using (XmlReader reader = XmlReader.Create(filePath)) { while (reader.Read()) { if (reader.NodeType == XmlNodeType.Element && (reader.Name == "svg" || reader.Name == "svg:svg")) { return true; // File is SVG } } } return true; // File is XML (no SVG element found) } catch (XmlException) { return false; // File is not well-formed XML } }
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This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Peter Volz 1,295 Reputation points

2023-06-15T00:19:03.1233333+00:00

Hello, thanks, seems not working on these SVG files:

https://dev.w3.org/SVG/tools/svgweb/samples/svg-files/anim1.svg
Castorix31 90,681 Reputation points

2023-06-15T08:22:07.0266667+00:00

ID2D1DeviceContext5::CreateSvgDocument can be used to check a .SVG, but it is a bit a sledgehammer to crack a nut...
Hui Liu-MSFT 48,676 Reputation points Microsoft External Staff

2023-06-15T08:47:13.4966667+00:00

Hi,@Peter Volz. Does the following code meet your needs? If not, could you share me a minimal example containing svg files and steps that can reproduce the problem to reproduce the problem and analyze it?

public void f(string filePath) { bool isSvgFile = string.Equals(System.IO.Path.GetExtension(filePath), ".svg", StringComparison.OrdinalIgnoreCase); if (isSvgFile) { MessageBox.Show("The file is an SVG file."); } else { MessageBox.Show("The file is not an SVG file."); } }
Peter Volz 1,295 Reputation points

2023-06-15T11:18:06.4166667+00:00

Thanks, not extension based, however, the exception was DTD prohibited related, seems that:

XmlReaderSettings.DtdProcessing > Ignore or Parse

will solve the problem, which one do you recommend? Ignore or Parse

and for XmlReaderSettings, do you have any suggestion to alter the default values to validate general XMLs and distinguish svg? :)
Dewayne Basnett 1,381 Reputation points

2023-06-15T14:17:29.2833333+00:00

If you have a svg file it can be read with XElement regardless of the presence of the xml declaration

<?xml version
Hui Liu-MSFT 48,676 Reputation points Microsoft External Staff

2023-06-16T02:30:14.69+00:00

Hi,@Peter Volz.The appropriate choice depends on your specific requirements and the level of DTD validation you need.

XmlReaderSettings.DtdProcessing.Ignore: This option ignores the DTD completely. It allows parsing the XML without performing DTD validation. If you are not concerned about DTD validation and just want to extract the data from the XML, this option can be sufficient. It avoids potential exceptions related to DTD usage.

XmlReaderSettings.DtdProcessing.Parse: This option enables DTD processing and performs DTD validation during parsing. It ensures that the XML adheres to the DTD rules. If you require DTD validation and want to ensure that the XML complies with the specified DTD, you cOULD choose this option. And note that enabling this option can introduce potential security risks if the XML contains untrusted or malicious external entities.

Answer 1

P a u l 10,761

You can use XmlReader. You call MoveToContent to move to the first element in the document, then the XmlReader instance will refer to the svg tag (or non-svg if it's a normal XML file):

using System.Xml;

{
	var xml = """
		 <svg width="400" height="110">
		  <rect width="300" height="100" style="fill:rgb(0,0,255);stroke-width:3;stroke:rgb(0,0,0)" />
		  Sorry, your browser does not support inline SVG.  
		</svg>
		""";

	using var xmlReader = XmlReader.Create(new StringReader(xml));

	xmlReader.MoveToContent();

	if (xmlReader.Name.Equals("svg", StringComparison.OrdinalIgnoreCase)) {
		Console.WriteLine("It's an SVG!");
	} else {
		Console.WriteLine("It is NOT an SVG!");
	}
}

{
	var xml = """
		<?xml version="1.0" encoding="UTF-8"?>
		<note>
		  <to>Tove</to>
		  <from>Jani</from>
		  <heading>Reminder</heading>
		  <body>Don't forget me this weekend!</body>
		</note>
		""";

	using var xmlReader = XmlReader.Create(new StringReader(xml));

	xmlReader.MoveToContent();

	if (xmlReader.Name.Equals("svg", StringComparison.OrdinalIgnoreCase)) {
		Console.WriteLine("It's an SVG!");
	} else {
		Console.WriteLine("It is NOT an SVG!");
	}
}

If you're reading from a file like your question suggests then you can just pass the filename to XmlReader.Create instead of the StringReader.

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This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Peter Volz 1,295 Reputation points

2023-06-15T00:19:10.5133333+00:00

Hello, thanks, seems not working on these SVG files:

https://dev.w3.org/SVG/tools/svgweb/samples/svg-files/anim1.svg
P a u l 10,761 Reputation points

2023-06-15T18:18:29.6266667+00:00
I'm not sure if you found the answer already but there's an DtdProcessing setting that needs to be set to avoid <DOCTYPE /> elements at the top of the SVG causing an exception to be thrown due to a potential security risk:

var response = await new HttpClient().GetAsync("https://dev.w3.org/SVG/tools/svgweb/samples/svg-files/anim1.svg"); var xml = await response.Content.ReadAsStringAsync(); using var xmlReader = XmlReader.Create(new StringReader(xml), new XmlReaderSettings { DtdProcessing = DtdProcessing.Ignore }); xmlReader.MoveToContent(); if (xmlReader.Name.Equals("svg", StringComparison.OrdinalIgnoreCase)) { Console.WriteLine("It's an SVG!"); } else { Console.WriteLine("It is NOT an SVG!"); }

Setting this to DtdProcessing.Ignore will just mean that XmlReader will safely skip over that element if it encounters it, which is fine for our case because we're only parsing the document to read the first element.

Answer 2

Peter Volz 1,295

Hello, thanks, seems not working on these SVG files:

https://dev.w3.org/SVG/tools/svgweb/samples/svg-files/anim1.svg

Answer 3

XElement use

        Dim doc As XElement = <svg width="500" height="500">
                                  <rect id="rec" x="300" y="100" width="300" height="100" style="fill:lime">
                                      <animate attributeName="x" attributeType="XML" begin="0s" dur="6s" fill="freeze" from="300" to="0"/>
                                      <animate attributeName="y" attributeType="XML" begin="0s" dur="6s" fill="freeze" from="100" to="0"/>
                                      <animate attributeName="width" attributeType="XML" begin="0s" dur="6s" fill="freeze" from="300" to="800"/>
                                      <animate attributeName="height" attributeType="XML" begin="0s" dur="6s" fill="freeze" from="100" to="300"/>
                                      <animate attributeName="fill" attributeType="CSS" from="lime" to="red" begin="2s" dur="4s" fill="freeze"/>
                                  </rect>
                              </svg>



        Dim s As String = doc.ToString
        Stop 'look at s, no <?xml version="1.0" encoding="utf-8"?>
        IO.File.WriteAllText("C:\Users\foo\Desktop\svgTest.svg", s)

        doc = Nothing
        Stop
        doc = XElement.Load("C:\Users\foo\Desktop\svgTest.svg")
        Stop

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Whixh XML Parser to use?

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