Validate xml against dtd from string

Question

I have an xml file that refers to a local dtd file. But the problem is that my files are being compressed into a single file (I am using Unity3D and it puts all my textfiles into one binary). This question is not Unity3D specific, it is useful for anyone that tries to load a DTD schema from a string.

I have thought of a workaround to load the xml and load the dtd separately and then add the dtd file to the XmlSchemas of my document. Like so:

private void ReadConfig(string filePath)
{
    // load the xml file
    TextAsset text = (TextAsset)Resources.Load(filePath);
    StringReader sr = new StringReader(text.text);
    sr.Read(); // skip BOM, Unity3D catch!

    // load the dtd file
    TextAsset dtdAsset = (TextAsset)Resources.Load("Configs/condigDtd");

    XmlSchemaSet schemaSet = new XmlSchemaSet();
    schemaSet.Add(...); // my dtd should be added into this schemaset somehow, but it's only a string and not a filepath.

    XmlReaderSettings settings = new XmlReaderSettings() { ValidationType = ValidationType.DTD, ProhibitDtd = false, Schemas = schemaSet};
    XmlReader r = XmlReader.Create(sr, settings);

    XmlDocument doc = new XmlDocument();
    doc.Load(r);
}

The xml starts like this, but the dtd cannot be found. Not strange, because the xml file was loaded as a string, not from a file.

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE Scene SYSTEM "configDtd.dtd">

score 2 · Accepted Answer · answered May 09 '12 at 11:15

XmlSchema has a Read method that takes in a Stream and a ValidationEventHandler. If the DTD is a string, you could convert it to a stream

System.Text.Encoding encode = System.Tet.Encoding.UTF8;
MemoryStream ms = new MemoryStream(encode.GetBytes(myDTD));

create the XmlSchema

XmlSchema mySchema = XmlSchema.Read(ms, DTDValidation);

add this schema to the XmlDocument containing the xml you are validating

myXMLDocument.Schemas.Add(mySchema);
myXMLDocument.Schemas.Compile();
myXMLDocument.Validate(DTDValidation);

The DTDValidation() handler would contain code handling what to do if the xml is invalid.

Thanks, it almost seemed to work. But Mono is throwing an xmlexception about declarations that could not be found. I think this would work if I would not be working in mono. So thumbs up for this one. I will try to use xsd files instead. — Marnix, May 09 '12 at 11:35

Validate xml against dtd from string

1 Answers1