XmlValidatingRe ader - just the FAQS?

[Nuevo Registrado]

All,

I am having a tough time figuring out how to code a simple app to read an
xml file and an xsd file and validate the xml file using the xsd without
using a namespace for the schema. Help? Also, is there a .NET XML FAQ?

Thanks,

Will

Here are the details:

----------the error
Validation Error: The 'HeadCount' element is not declared. An error
occurred at file:///d:/xml/config.xml, (2, 2).
Validation Error: The 'Name' element is not declared. An error occurred
at file:///d:/xml/config.xml, (3, 4).
Validation Error: The 'Name' element is not declared. An error occurred
at file:///d:/xml/config.xml, (4, 4).
----------the error
----------config.xml
<?xml version="1.0" encoding="UTF-8"?>
<HeadCount>
<Name>Waldo Pepper</Name>
<Name>Red Pepper</Name>
</HeadCount>
----------config.xml
----------config.xsd
<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema xmlns:xsd="http ://www.w3.org/2001/XMLSchema">
<xsd:element name='HeadCount ' type="HEADCOUNT "/>
<xsd:complexTyp e name="HEADCOUNT ">
<xsd:sequence >
<xsd:element name='Name' type='xsd:strin g' maxOccurs='unbo unded'/>
</xsd:sequence>
<xsd:attribut e name='division' type='xsd:int' use='optional'
default='8'/>
</xsd:complexType >
</xsd:schema>
----------config.xsd

----------doit.cs
class Tester
{
static void Main()
{
String strXml;
String strXsd;

strXml = @"d:\xml\config .xml";

strXsd = @"d:\xml\config .xsd";

Tester cs = new Tester();
cs.Validate(str Xml, strXsd);
}

private void Validate(String strXml, String strXsd)
{
try
{
XmlSchemaCollec tion sc = new XmlSchemaCollec tion();
sc.ValidationEv entHandler += new ValidationEvent Handler
(ValidationCall Back);
sc.Add(null, strXsd);

XmlTextReader textReader = new XmlTextReader(s trXml);
XmlValidatingRe ader validatingReade r = new XmlValidatingRe ader
(textReader);
validatingReade r.ValidationTyp e = ValidationType. Schema;
XmlSchema schema = new XmlSchema();
schema.SourceUr i = strXsd;
validatingReade r.Schemas.Add(s chema);
validatingReade r.ValidationEve ntHandler += new
ValidationEvent Handler(Validat ionCallBack);
while (validatingRead er.Read());
}
catch (System.Excepti on exc)
{
System.Console. Write("big bad error: \n" + exc.ToString()) ;
}
}

private void ValidationCallB ack(object sender, ValidationEvent Args e)
{
Console.WriteLi ne("Validation Error: {0}", e.Message);
}
}
----------doit.cs

[Derek Harmon]

"Nuevo Registrado" <nu***@registra do.com> wrote in message news:Xn******** **************@ 207.46.248.16.. .

read an xml file and an xsd file and validate the xml file using
the xsd without using a namespace for the schema.
The XML schema is fine, and your instance document is valid by it,
so the problem is not with these.
Validation Error: The 'HeadCount' element is not declared. An error
occurred at file:///d:/xml/config.xml, (2, 2).
Validation Error: The 'Name' element is not declared. An error occurred
at file:///d:/xml/config.xml, (3, 4).
Validation Error: The 'Name' element is not declared. An error occurred
at file:///d:/xml/config.xml, (4, 4).
Anytime I get a validation error for every possible piece of XML
in my instance document, I ask myself a question: did I really
load an XML schema, at all?

Because I have to figure that if I'm validating an instance
document against an XML schema without any declarations (i.e.,
an empty one), these are precisely the sorts of validation
errors I'd expect.
----------doit.cs
Starsky & Hutch fan?
XmlSchemaCollec tion sc = new XmlSchemaCollec tion();
sc.ValidationEv entHandler += new ValidationEvent Handler
(ValidationCall Back);
sc.Add(null, strXsd);
These lines _would_ work (and you're right on, passing null
to indicate that the schema targets no namespace), except
that the XmlSchemaCollec tion, sc, is entirely disconnected
from any of the other variables found in this method.
XmlSchema schema = new XmlSchema();
The XmlSchema constructor should only appear in applications
that are directly programming the Schema Object Model (SOM).

Whenever this line appears in an application that is just
validating an instance document against a ready-made schema,
it's got to raise a brightly colored -- if not red -- flag.
schema.SourceUr i = strXsd;
It's probably a common misconception that setting SourceUri
causes a schema to be loaded; this is not actually what
happens.

The SourceUri property exists so that an XmlSchema can be
told what it's base path and resource are. As far as the
XmlSchema knows, it's been created from some nameless stream
of characters and only the application can give it a meaning-
ful context for it to use as it's Base URI. That's what the
SourceUri property is meant for.
validatingReade r.Schemas.Add(s chema);

Adds what I'm afraid is an absolutely empty XmlSchema to the
XmlSchemaCollec tion of this XmlValidatingRe ader. :-(

OK, there are 2 ways to resolve this. The first goes with
your winning strategy at the very top of the method, but then
instead of adding an XmlSchema to an XmlSchemaCollec tion that
isn't connected to anything else -- add it to the XmlSchema-
Collection on your XmlValidatingRe ader.

validatingReade r.Schemas.Add( null, strXsd);

If you still want to access the XmlSchema object you've just
added, that's possible too, since Add() returns the newly
created XmlSchema object.

XmlSchema schema = validatingReade r.Schemas.Add( null, strXsd);
schema.SourceUr i = strXsd;

The second solution is to use the static Read() method of
XmlSchema. Nine times out of 10, this is always what you
want to do instead of using the XmlSchema() constructor
when you're validating an instance document against an
existing XML schema document.

XmlSchema schema = XmlSchema.Read( new XmlTextWriter( strXsd), null);
schema.SourceUr i = strXsd;
validatingReade r.Schemas.Add( schema);

The null argument I passed to Read() is an optional Validation-
EventHandler that allows you to receive notifications of any
warnings or errors caused while loading the XML schema document.

Either of these approaches should allow you to see that the
schema document validates your instance document without any
validation errors. :-)
Derek Harmon

[Nuevo Registrado]

Using the advice in this note, I was able to get it working. Would you
mind taking a look at my solution and telling me if it's overkill - ie.
is there a more succinct solution:

XmlSchema schema = XmlSchema.Read( new XmlTextReader(s trXsd), null);
schema.SourceUr i = strXsd;
XmlValidatingRe ader validatingReade r = new XmlValidatingRe ader(new
XmlTextReader(s trXml));
validatingReade r.Schemas.Add(s chema);
validatingReade r.ValidationEve ntHandler += new ValidationEvent Handler
(ValidationCall Back);
while (validatingRead er.Read());

OK, and while we're on the subject why not supply a Read function like:
Read(XMLFile, XSDFile);
or
Read(XmlTextRea der XmlReader, XmlTextReader XsdReader,
ValidationCallB ack);

is it really that hard to anticipate the likelihood of wanting to do this
- frequently?

Derek, many thanks for your comprehensive and lucid explanation. The
reason that the schema collection was disconnected was an oversight on my
part - I had started off with one tack and finished with another - copy
and paste syndrome. I appreciate your clear answers in the face of what
might have appeared to have been air-headedness. The 'answer' was that
the schema was never 'read' and considering the weak XML related
documentation included in the MSDN library, I might never have 'figured'
it out, if it hadn't been for your kindness. Props!

Thanks,

Will
"Derek Harmon" <lo*******@msn. com> wrote in
news:OZ******** ******@TK2MSFTN GP09.phx.gbl:

"Nuevo Registrado" <nu***@registra do.com> wrote in message
news:Xn******** **************@ 207.46.248.16.. .

read an xml file and an xsd file and validate the xml file using
the xsd without using a namespace for the schema.

The XML schema is fine, and your instance document is valid by it,
so the problem is not with these.

Validation Error: The 'HeadCount' element is not declared. An error
occurred at file:///d:/xml/config.xml, (2, 2).
Validation Error: The 'Name' element is not declared. An error
occurred at file:///d:/xml/config.xml, (3, 4).
Validation Error: The 'Name' element is not declared. An error
occurred at file:///d:/xml/config.xml, (4, 4).

Anytime I get a validation error for every possible piece of XML
in my instance document, I ask myself a question: did I really
load an XML schema, at all?

Because I have to figure that if I'm validating an instance
document against an XML schema without any declarations (i.e.,
an empty one), these are precisely the sorts of validation
errors I'd expect.

----------doit.cs

Starsky & Hutch fan?

XmlSchemaCollec tion sc = new XmlSchemaCollec tion();
sc.ValidationEv entHandler += new ValidationEvent Handler
(ValidationCall Back);
sc.Add(null, strXsd);

These lines _would_ work (and you're right on, passing null
to indicate that the schema targets no namespace), except
that the XmlSchemaCollec tion, sc, is entirely disconnected
from any of the other variables found in this method.

XmlSchema schema = new XmlSchema();

The XmlSchema constructor should only appear in applications
that are directly programming the Schema Object Model (SOM).

Whenever this line appears in an application that is just
validating an instance document against a ready-made schema,
it's got to raise a brightly colored -- if not red -- flag.

schema.SourceUr i = strXsd;

It's probably a common misconception that setting SourceUri
causes a schema to be loaded; this is not actually what
happens.

The SourceUri property exists so that an XmlSchema can be
told what it's base path and resource are. As far as the
XmlSchema knows, it's been created from some nameless stream
of characters and only the application can give it a meaning-
ful context for it to use as it's Base URI. That's what the
SourceUri property is meant for.

validatingReade r.Schemas.Add(s chema);

Adds what I'm afraid is an absolutely empty XmlSchema to the
XmlSchemaCollec tion of this XmlValidatingRe ader. :-(

OK, there are 2 ways to resolve this. The first goes with
your winning strategy at the very top of the method, but then
instead of adding an XmlSchema to an XmlSchemaCollec tion that
isn't connected to anything else -- add it to the XmlSchema-
Collection on your XmlValidatingRe ader.

validatingReade r.Schemas.Add( null, strXsd);

If you still want to access the XmlSchema object you've just
added, that's possible too, since Add() returns the newly
created XmlSchema object.

XmlSchema schema = validatingReade r.Schemas.Add( null, strXsd);
schema.SourceUr i = strXsd;

The second solution is to use the static Read() method of
XmlSchema. Nine times out of 10, this is always what you
want to do instead of using the XmlSchema() constructor
when you're validating an instance document against an
existing XML schema document.

XmlSchema schema = XmlSchema.Read( new XmlTextWriter( strXsd),
null); schema.SourceUr i = strXsd;
validatingReade r.Schemas.Add( schema);

The null argument I passed to Read() is an optional Validation-
EventHandler that allows you to receive notifications of any
warnings or errors caused while loading the XML schema document.

Either of these approaches should allow you to see that the
schema document validates your instance document without any
validation errors. :-)
Derek Harmon

[Derek Harmon]

"Nuevo Registrado" <nu***@registra do.com> wrote in message news:Xn******** *************** @207.46.248.16. ..

Using the advice in this note, I was able to get it working. Would you
mind taking a look at my solution and telling me if it's overkill - ie.
is there a more succinct solution:

XmlSchema schema = XmlSchema.Read( new XmlTextReader(s trXsd), null);
schema.SourceUr i = strXsd;
XmlValidatingRe ader validatingReade r = new XmlValidatingRe ader(new
XmlTextReader(s trXml));
validatingReade r.Schemas.Add(s chema);
validatingReade r.ValidationEve ntHandler += new ValidationEvent Handler
(ValidationCall Back);
while (validatingRead er.Read());

Not overkill, but it can be shortened by one-line into,

XmlSchema schema = validatingReade r.Schemas.Add( null, strXsd);
schema.SourceUr i = strXsd;
XmlValidatingRe ader validatingReade r = new XmlValidatingRe ader(
new XmlTextReader( strXml));
validatingReade r.ValidationEve ntHandler += new ValidationEvent Handler(
ValidationCallB ack);
while (validatingRead er.Read( ));

only because when you Add the file name to the XmlSchemaCollec tion
it will create an XmlTextReader and do the XmlSchema.Read for you.

In fact, since there is only one property on XmlSchema that's of interest
to your application, the first two lines can be compacted into:

validatingReade r.Schemas.Add( null, strXsd).SourceU ri = strXsd;

but that's getting a bit flamboyant for my tastes. I'd rather hold onto an
XmlSchema object reference if there's any chance I'd be interested in
more than one of it's properties in the future.
Derek Harmon