Xml Schema error

Question

I am using Visual Studio 2008 Pro and programming in Visual Basic and having some issues with Xml schemas.

I’ve created an Xml schema file that I hope to use to validate an Xml data file. I want to be able to control whether and how the datafile is read when it contains an error. My goal is to validate and import the data (from the Xml file) to a dataSet and then process it. It looks like I am having problems with the the Xml shema. When I try to read the data I get errors for each element and line of data in the Xml table. The errors look like this:

 

Validation Error: Could not find schema information for the element 'TFRTable'.

 

I have included my code, Xml schema and a piece of the Xml data file below. Any plain language help would be much appreciated.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim ds As New DataSet, rdr As XmlReader
Dim myXmlFile As String = "C:\someFile.xml", schemaFile As String = " C:\someFile.xsd"
rdr = readXmlWithXmlReader(schemaFile, myXmlFile)
ds.ReadXml(rdr, XmlReadMode.IgnoreSchema)
DataGridView1.DataSource = ds
DataGridView1.DataMember = ds.Tables(0).TableName
End Sub
Function readAndValidate(ByVal schemaFileStr As String, ByVal xmlFileStr As String) As XmlReader
        Dim xsc As XmlSchemaSet = New XmlSchemaSet()
        xsc.Add(Nothing, schemaFileStr)  
        Dim settings As New XmlReaderSettings()
        settings.ConformanceLevel = ConformanceLevel.Document
        settings.IgnoreWhitespace = True
        settings.IgnoreComments = True
        settings.ValidationType = ValidationType.Schema
        settings.Schemas = xsc
        settings.ValidationFlags = XmlSchemaValidationFlags.ReportValidationWarnings
        AddHandler settings.ValidationEventHandler, AddressOf validator
        Dim reader As XmlReader = XmlReader.Create(xmlFileStr, settings)
       While reader.Read()
       End While
       Return reader
End Function
Sub validator(ByVal sender As Object, ByVal e As ValidationEventArgs)
        Console.WriteLine("Validation Error: {0}", e.Message)
End Sub

XML Schema:

<?xml version="1.0" encoding="utf-8"?>

<xs:schema id="FertSchema"

    targetNamespace="http://tempuri.org/FertSchema.xsd"

    elementFormDefault="qualified"

    xmlns="http://tempuri.org/FertSchema.xsd"

    xmlns:mstns="http://tempuri.org/FertSchema.xsd"

    xmlns:xs="http://www.w3.org/2001/XMLSchema">

  <xs:simpleType name="yearType" >

    <xs:restriction base="xs:unsignedShort">

      <xs:minInclusive value="1971" />

      <xs:maxInclusive value ="2101"/>

    </xs:restriction>

   </xs:simpleType>

  <xs:simpleType name="tfrType" >

    <xs:restriction base="xs:decimal">

      <xs:minInclusive value="0" />

      <xs:maxExclusive value="1" />

    </xs:restriction>

  </xs:simpleType>

  <xs:simpleType name="frType" >

    <xs:restriction base="xs:decimal">

      <xs:minInclusive value="0" />

      <xs:maxExclusive value="10" />

    </xs:restriction>

  </xs:simpleType>

    <xs:element name="TFRTable">

    <xs:complexType>

      <xs:sequence>

        <xs:element maxOccurs="unbounded" minOccurs="1" name="TFRRow">

          <xs:complexType>

            <xs:sequence>

              <xs:element name="Year" minOccurs="1"  type="yearType"  />

              <xs:element minOccurs="1"  name="tfr" type="tfrType"/>

              <xs:element minOccurs="1"  name="fr1519" type="frType" />

              <xs:element minOccurs="1"  name="fr2024" type="frType"/>

              <xs:element minOccurs="1"  name="fr2529" type="frType"/>

              <xs:element minOccurs="1"  name="fr3034" type="frType"/>

              <xs:element minOccurs="1"  name="fr3539" type="frType"/>

              <xs:element minOccurs="1"  name="fr4044" type="frType"/>

              <xs:element minOccurs="1"  name="fr4549" type="frType"/>

              <xs:element  minOccurs="1" name="mbr" type="frType" />

            </xs:sequence>

          </xs:complexType>

        </xs:element>

      </xs:sequence>

    </xs:complexType>

  </xs:element>

  </xs:schema>

Extract from XML table file:

<? xml version="1.0" encoding="UTF-8" standalone="yes"?>

<TFRTable xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

<TFRRow>

<Year>1971</Year>

<tfr>2.1271</tfr>

<fr1519>0.03988 </fr1519>

<fr2024>0.1293</fr2024>

<fr2529>0.13774</fr2529>

<fr3034>0.07526</fr3034>

<fr3539>0.03334</fr3539>

<fr4044>0.0093</fr4044>

<fr4549>0.0006</fr4549>

<mbr>0.51314</mbr>

</TFRRow> 

.

.

</TFRTable>

Answer 1

Hi Siansun,

Thanks for you post.

This forum is a VB.Net forum. There is a special forum to deal with XML issue. For better support, I will move this thread to XML, System.Xml, MSXML and XmlLite forum. It will cost a little time to involve the members in this forum. I appreciate your patience.

Sorry for any incontinences and have a nice day.

---

Mark Liu-lxf [MSFT]
MSDN Community Support | Feedback to us

Answer 2

OK. Noted. Thanks

Answer 3

Your schema has a target namespace in which it defines its elements, your XML instance document however does not use any namespace.

And your .NET code enables warnings for the XmlReader, yet then you simply output Console.WriteLine("Validation Error: {0}", e.Message) without checking the e.Severity type.

I think the validation event handler outputs a warning and that warning is correct, as your instance document has a root element named "TFRTable" in no namespace while your schema wants an element of that name in the target namespace. So you could use

  <TFRTable xmlns="http://tempuri.org/FertSchema.xsd">...</TFRTable>

in your instance document, that should avoid the warning the validating XmlReader emits to your validation event handler.

---

MVP Data Platform Development My blog

Answer 4

Martin, thanks for that. You're right. It was a warning and not an error. Your suggestion did remove the warning. By the way, in case you tried to reproduce what I did, there was an error in the xml code listing: in the orginal listing the maxExclusive value for "tfrType" was set to 1; it should have been set to 10, as shown below.

I still have a problem with the code, however; the data does not get read into the dataSet, so I end up with an empty dataSet. Any thoughts/suggestions?

Thanks

 <xs:simpleType name="tfrType" >
    <xs:restriction base="xs:decimal">
      <xs:minInclusive value="0" />
      <xs:maxExclusive value="10" />
    </xs:restriction>
  </xs:simpleType>

Answer 5

Please explain in more detail what you want to achieve, usually you would either use a validating XmlReader to validate an XML document or you would use a DataSet with ReadXmlSchema first, then ReadXml to load data in a DataSet. Admittedly the second way does not validate all the items that a validating XmlReader checks.

As for your code, you seem to want to use an XmlReader for validation to be passed in to ReadXml, that is not going to work as XmlReader is a forwards only, one time way to read through an XML document. If you use one XmlReader to read through the XML document and then pass that XmlReader on to another method then there are no more nodes to be consumed by that other method. Thus if you really want to validate first and then read the document into a DataSet I would suggest that you set up your XmlReader without doing the while Read() loop, instead you pass in the XmlReader to the ReadXml method of the DataSet, that way the DataSet should consume the XmlReader and the reader will do the validation. Or as an alternative separate the two steps, use your XmlReader for validation, then simply do DataSet.ReadXml(fileLocation) to read the XML into the data set.

---

MVP Data Platform Development My blog

Answer 6

Martin your comments were very helpful. I removed the 'While Read()' loop and everything worked fine. I also found an alternate solution that involves reading the Xml file and Xsd file each into an XDocument, then using the 'Validate' extension method on the Xml-document.

Sub validateFile(ByVal xmlDoc As XDocument, ByVal xsdDoc As XDocument)
'== Validate the xml file
Dim schemaSet As New XmlSchemaSet schemaSet.Add(Nothing, xsdDoc.CreateReader)
xmlDoc.Validate(schemaSet, AddressOf validator)
End Sub
 
Sub validator(ByVal sender As Object, ByVal e As ValidationEventArgs)
If (e.Severity = XmlSeverityType.Warning) Then
  Console.WriteLine("Warning: " & e.Message)
Else
  Console.WriteLine("Validation error message: " & vbCrLf & e.Message)
   Exit Sub
   End If
End Sub