使用 Saxon API C# 根据 XSD 验证 XML 不报告所有验证错误

Question

I am trying to validate xml against xsd using saxon api for C#.Net. However, it is not catching all the validation errors in one go. All the elements which violate data type are getting caught, but if the structure is badly formed with multiple errors in it, then it catches only the first error. I have created the sample code as below

XSD File

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:books" xmlns:bks="urn:books">
    <xsd:element name="books" type="bks:BooksForm"/>
    <xsd:complexType name="BooksForm">
        <xsd:sequence>
            <xsd:element name="book" type="bks:BookForm" minOccurs="0" maxOccurs="unbounded"/>
        </xsd:sequence>
    </xsd:complexType>
    <xsd:complexType name="BookForm">
        <xsd:sequence>
            <xsd:element name="author" type="xsd:string"/>
            <xsd:element name="title" type="xsd:string"/>
            <xsd:element name="genre" type="xsd:string"/>
            <xsd:element name="price" type="xsd:float" />
            <xsd:element name="pub_date" type="xsd:date" />
            <xsd:element name="review" type="xsd:string"/>
        </xsd:sequence>
        <xsd:attribute name="id" type="xsd:string"/>
    </xsd:complexType>
</xsd:schema>

Xml File

<?xml version="1.0"?>
<x:books xmlns:x="urn:books">
    <book id="bk001">
        <author>Writer</author>
        <title>The First Book</title>
        <genre>Fiction</genre>
        <price>44.95</price>
        <pub_date>2000-10-01</pub_date>
        <review>An amazing story of nothing.</review>
    </book>

    <book id="bk002">
        <author>Poet</author>
        <title>The Poet's First Poem</title>
        <genre>Poem</genre>
        <price>ABC</price>
        <review>Least poetic poems.</review>
    </book>

    <book id="bk003">
        <bad_element_1></bad_element_1>
        <bad_element_2></bad_element_2>
        <author>Writer</author>
        <title>The First Book</title>
        <genre>Fiction</genre>
        <price>ABC</price>
        <pub_date>2000-10-01</pub_date>
        <review>An amazing story of nothing.</review>
    </book>
</x:books>

C# Code

public void run(string xmlPath, string xsdPath)
        {
            EnterpriseConfiguration conf = new EnterpriseConfiguration();
            conf.setConfigurationProperty(FeatureKeys.LICENSE_FILE_LOCATION, @"C:\saxon\saxon-license.lic");
            Processor processor = new Processor(conf);
            processor.SetProperty("http://saxon.sf.net/feature/timing", "true");
            processor.SetProperty("http://saxon.sf.net/feature/validation-warnings", "false"); //Set to true to suppress the exception
            SchemaManager manager = processor.SchemaManager;
            manager.XsdVersion = "1.1";
            List<Error> errorList = new();
            manager.ErrorReporter = err => errorList.Add(err);
            XmlReader xsdReader = XmlReader.Create(xsdPath);
            try
            {
                manager.Compile(xsdReader);
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
                Console.WriteLine("Schema compilation failed with " + errorList.Count + " errors");
                foreach (Error error in errorList)
                {
                    Console.WriteLine("At line " + error.Location.LineNumber + ": " + error.Message);
                }
                return;
            }
            SchemaValidator validator = manager.NewSchemaValidator();
            XmlReaderSettings xmlReaderSettings = new XmlReaderSettings();
            xmlReaderSettings.ValidationType = ValidationType.Schema;
            xmlReaderSettings.ValidationFlags = XmlSchemaValidationFlags.ProcessInlineSchema | XmlSchemaValidationFlags.ReportValidationWarnings;
            XmlReader xmlReader = XmlReader.Create(xmlPath, xmlReaderSettings);
            Console.WriteLine("Validating input file " + xmlPath);
            List<ValidationFailure> errors = new();
            validator.InvalidityListener = failure => errors.Add(failure);
            XdmDestination psvi = new();
            validator.SetDestination(psvi);
            try
            {
                validator.Validate(xmlReader);
            }
            catch (Exception e)
            {
                Console.WriteLine(e); Console.WriteLine(); Console.WriteLine();
                Console.WriteLine("Instance validation failed with " + errors.Count + " errors"); Console.WriteLine(); Console.WriteLine();
                foreach (ValidationFailure error in errors)
                {
                    Console.WriteLine("At line " + error.LineNumber + ": " + error.Message); Console.WriteLine(); Console.WriteLine();
                }
                return;
            }
            Console.WriteLine("Input file is valid");
        }

Output This image shows the console screen

The highlighted validation error in this image is not caught in the output

Please help. Thanks.

I am expecting to catch all the validation errors in one go.

Answer 1

Generally if the content of an element (the sequence of children) doesn't match the content model defined for that element in the schema, Saxon regards that as one validation error, and doesn't attempt further validation until it gets to the end of the invalid element.

Error recovery from parsing errors is a bit of an art and there's no universal solution; the one thing people hate is when it's done incorrectly leading to hundreds of spurious errors.

In your particular example you're highlighting that there's no error reported for bad_element2. But how is the processor supposed to know what can validly follow a bad_element1? The schema doesn't say. You've already departed from the rule book, the processor can't find a rule to apply here.

You could adopt the approach that the schema doesn't allow anything after a bad_element1, and therefore anything that follows is another error. But that would lead to lots of spurious errors that you don't want.