Summary

TXmlSerializer is a specialized TSerializer class type for writing values in XML format, using standard VCL XML classes, such as TXmlDocument.

Syntax 

TXmlSerializer = class(TSerializer)

Constructors

Properties

 NameDescription
RootValue

Allows to specify XML element name for subsequently serializing root-level value.

Top

Remarks

TXmlSerializer object should be created providing a reference to existing IXMLNode object into which all serializing data will be written. Each root-level data value will be written as a child of provided IXMLNode object. TXmlSerializer creates new IXmlNode for every serializing value using IXmlNode.AddChild method; thus every serializing value will be added as last child of the parent node, respecting ordered nature of  XML documents.

Every element in XML document should have a name (sometimes called "tag"). Since core serializer API does not support root-level values naming, additional API has been provided: NG.Serialization.Xml.TXmlSerializer.RootValue(string) property should be used before actual writing of any root-level value (otherwise, invalid state exception will be thrown):

DelphiCopyCode imageCopy Code 
szr.RootValue['MyValue'].Value(7);

Since, NG.Serialization.Xml.TXmlSerializer.RootValue(string) is a default indexed property, its property name can be suppressed to make code more readable:

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szr['MyValue'].Value(7);

If a value need to be serialized as a root document node, TXmlDocument.Node can be specified as a constructor argument while creating TXmlSerializer object:

DelphiCopyCode imageCopy Code 
xml := TXmlDocument.Create(nil);
xml.Active := True;

szr := TXmlSerializer.Create(xml.Node);
try
  srz['Book'].Value<TBook>(book);
finally
  srz.Free;
end;
The above code will result in the following XML:
XmlCopyCode imageCopy Code 
<Book>
  <Tittle>Delphi XE Handbook</Tittle>
  <Author>Marco Cantu</Author>
</Book>
However, since xml document allows only single root node, an attempt to write more than one value this way will result in an Xml DOM handling error.

Examples

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xml         := TXmlDocument.Create(nil);
xml.Options := xml.Options + [doNodeAutoIndent];
xml.Active  := True;
rootNode    := xml.ChildNodes['Books'];

szr := TXmlSerializer.Create(rootNode);
try
  srz['Book'].Value<TBook>(book1);
  srz['Book'].Value<TBook>(book2);
finally
  szr.Free;
end;

xml.SaveToFile('Books.xml');