My current task involves writing a class library for processing HL7 CDA files.
These HL7 CDA files are XML files with a defined XML schema, so I used xsd.exe to generate .NET classes for XML serialization and deserialization.
The XML Schema contains various types which contain
the mixed="true" attribute, specifying that an XML node of this type may contain normal text mixed with other XML nodes.
The relevant part of
the XML schema for one of these types looks like this:
<xs:complexType name="StrucDoc.Paragraph" mixed="true">
<xs:sequence>
<xs:element name="caption" type="StrucDoc.Caption" minOccurs="0"/>
<xs:choice minOccurs="0" maxOccurs="unbounded">
<xs:element name="br" type="StrucDoc.Br"/>
<xs:element name="sub" type="StrucDoc.Sub"/>
<xs:element name="sup" type="StrucDoc.Sup"/>
<!-- ...other possible nodes... -->
</xs:choice>
</xs:sequence>
<xs:attribute name="ID" type="xs:ID"/>
<!-- ...other attributes... -->
</xs:complexType>
The generated code for this type looks like this:
/// <remarks/>
[System.CodeDom.Compiler.GeneratedCodeAttribute("xsd", "2.0.50727.3038")]
[System.SerializableAttribute()]
[System.Diagnostics.DebuggerStepThroughAttribute()]
[System.ComponentModel.DesignerCategoryAttribute("code")]
[System.Xml.Serialization.XmlTypeAttribute(TypeName="StrucDoc.Paragraph", Namespace="urn:hl7-org:v3")]
public partial class StrucDocParagraph {
private StrucDocCaption captionField;
private object[] itemsField;
private string[] textField;
private string idField;
// ...fields for other attributes...
/// <remarks/>
public StrucDocCaption caption {
get {
return this.captionField;
}
set {
this.captionField = value;
}
}
/// <remarks/>
[System.Xml.Serialization.XmlElementAttribute("br", typeof(StrucDocBr))]
[System.Xml.Serialization.XmlElementAttribute("sub", typeof(StrucDocSub))]
[System.Xml.Serialization.XmlElementAttribute("sup", typeof(StrucDocSup))]
// ...other possible nodes...
public object[] Items {
get {
return this.itemsField;
}
set {
this.itemsField = value;
}
}
/// <remarks/>
[System.Xml.Serialization.XmlTextAttribute()]
public string[] Text {
get {
return this.textField;
}
set {
this.textField = value;
}
}
/// <remarks/>
[System.Xml.Serialization.XmlAttributeAttribute(DataType="ID")]
public string ID {
get {
return this.idField;
}
set {
this.idField = value;
}
}
// ...properties for other attributes...
}
If I deserialize an XML element where
the paragraph node looks like this:
<paragraph>first line<br /><br />third line</paragraph>
The result is that
the item and text arrays are read like this:
itemsField = new object[]
{
new StrucDocBr(),
new StrucDocBr(),
};
textField = new string[]
{
"first line",
"
third line",
};
From this there is no possible way to determine
the exact order of
the text and
the other nodes.
If I serialize this again,
the result looks exactly like this:
<paragraph>
<br />
<br />first linethird line
</paragraph>
The default serializer just serializes
the items first and then
the text.
I tried implementing IXmlSerializable on
the StrucDocParagraph class so that I could control
the deserialization and serialization of
the content, but it's rather complex since there are so many classes involved and I didn't come to a solution yet because I don't know if
the effort pays off.
Is there some kind of easy workaround to this problem, or is it even possible by doing custom serialization via IXmlSerializable?
Or should I just use XmlDocument or XmlReader/XmlWriter to process these documents?
