Error Handling

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Error handling when reading XML data

Errors in the structure of the XML data (no well formed) cause System.Xml.XmlException to be thrown.

Errors encountered when de-serializing an XML document are reported via the LxDeserializerErrorHandler Delegate. You can configure your own handler by setting the ErrorHandler Property on the LxReaderSettings Class.

Reading data from the generated classes	Copy Code
public void Read() { LxSerializer<BookstoreElm> serializer = new LxSerializer<BookstoreElm>(); LxReaderSettings lxReaderSettings = new LxReaderSettings(); lxReaderSettings.ErrorHandler = MyDeserializerErrorHandler; BookstoreElm bookstore = serializer.Deserialize(@"..\..\BookstoreSample.xml", lxReaderSettings); } public void MyDeserializerErrorHandler(string msg, LxErrorSeverity severity, LxErrorCode errorCode, TextLocation location, object targetObject) { if (severity == LxErrorSeverity.Error) throw new Exception(msg); else if (severity == LxErrorSeverity.Warning) Console.WriteLine(msg); }

Reading data from the generated classes

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public void Read()
{
    LxSerializer<BookstoreElm> serializer = new LxSerializer<BookstoreElm>();

    LxReaderSettings lxReaderSettings = new LxReaderSettings();
    lxReaderSettings.ErrorHandler = MyDeserializerErrorHandler;

    BookstoreElm bookstore = serializer.Deserialize(@"..\..\BookstoreSample.xml", lxReaderSettings);
}

public void MyDeserializerErrorHandler(string msg, LxErrorSeverity severity, LxErrorCode errorCode, TextLocation location, object targetObject)
{
    if (severity == LxErrorSeverity.Error)
        throw new Exception(msg);
    else if (severity == LxErrorSeverity.Warning)
        Console.WriteLine(msg);
}

Broadly speaking errors can be dealt with in 3 ways :-

Log and ignore - The error handler should just return. The reader will recover and continue reading. However, it should be noted that this may cause a cascade of errors to follow, the LxErrorCode parameter will provide more detail.
Stop reading - an exception should be raised by the error handler.
Fix the issue - This is only possible if you have a document that contains a specific defect that you intend to fix as its read. The 'targetObject' property provides the object that has caused the error, so it is possible to fix the objects issue within the error handler. The preferred method is the fix the issue downstream or by pre-processing the XML.

Continuing execution after an error (i.e. not throwing an exception within the error handler) may result in further errors and node being classified as unexpected.

Error handling when Writing XML data

Errors encountered when serializing a the XML Data Model into XML are reported via the LxSerializerErrorHandler Delegate. You can configure your own handler by setting the ErrorHandler Property on the LxWriterSettings Class.

Writing data from a generated classes	Copy Code
public void Write() { BookstoreElm bookstore = new BookstoreElm(); BookTypeCt book = new BookTypeCt(); book.Seq.Title = "Artemis"; book.Seq.Author.Seq.First_Name = "Andy"; book.Seq.Author.Seq.Last_Name = "Weir"; book.Seq.Genre = BookTypeCt.GenreEnum.Science_Fiction; book.Price = 7.99; book.ISBN = "978-1-78-503025-3"; book.Publicationdate = LxDateTime.CreateDate(2017, 4, 23); bookstore.Seq.Book.Add(book); LxSerializer<BookstoreElm> serializer = new LxSerializer<BookstoreElm>(); LxWriterSettings lxWriterSettings = new LxWriterSettings(); lxWriterSettings.ErrorHandler = MySerializerErrorHandler; serializer.Serialize(@"..\..\BookstoreSample.xml", bookstore, lxWriterSettings); } public void MySerializerErrorHandler(string msg, LxErrorSeverity severity, LxErrorCode errorCode, object targetObject) { if (severity == LxErrorSeverity.Error) throw new Exception(msg); else if (severity == LxErrorSeverity.Warning) Console.WriteLine(msg); }

Writing data from a generated classes

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public void Write()
{
    BookstoreElm bookstore = new BookstoreElm();
    BookTypeCt book = new BookTypeCt();
    book.Seq.Title = "Artemis";
    book.Seq.Author.Seq.First_Name = "Andy";
    book.Seq.Author.Seq.Last_Name = "Weir";
    book.Seq.Genre = BookTypeCt.GenreEnum.Science_Fiction;
    book.Price = 7.99;
    book.ISBN = "978-1-78-503025-3";
    book.Publicationdate = LxDateTime.CreateDate(2017, 4, 23);
    bookstore.Seq.Book.Add(book);

    LxSerializer<BookstoreElm> serializer = new LxSerializer<BookstoreElm>();
    LxWriterSettings lxWriterSettings = new LxWriterSettings();
    lxWriterSettings.ErrorHandler = MySerializerErrorHandler;

    serializer.Serialize(@"..\..\BookstoreSample.xml", bookstore, lxWriterSettings);
}

public void MySerializerErrorHandler(string msg, LxErrorSeverity severity, LxErrorCode errorCode, object targetObject)
{
    if (severity == LxErrorSeverity.Error)
        throw new Exception(msg);
    else if (severity == LxErrorSeverity.Warning)
        Console.WriteLine(msg);
}

Broadly speaking errors can be dealt with in 2 ways :-

Log and ignore - The error handler should just return. The writer will recover and continue, however the resulting XML will be invalid.
This approach can also be used to validate the XML Data Model, and produce a list of errors.
Stop writing - an exception should be raised by the error handler.