Customizing XSD->Classes code generation, the "easy" way
Update: check a more thorough explanation of this techique in
Code Generation in the .NET Framework Using XML Schema article
published in the MSDN XML DevCenter, and the companion post on the VS.NET custom tool for it.
I've always been disgusted by the imposibility to customize XSD.EXE tool. I've
even thought about some
workaround for the all-public-fields issue. However, I was
WRONG. It's perfectly possible to generate fully customized classes
from an XSD Schema, if not by calling XSD.EXE, by reusing the very same classes
it uses.
This is achievable without any reflection hack! All public
(althought certainly undocumented) classes and methods are used.
The "trick" involves using two key classes: XmlSchemaImporter and
XmlCodeExporter, both from the System.Xml.Serialization
namespace.
// Load the schema to process.
XmlSchema xsd = XmlSchema.Read( stm, null );
// Collection of schemas for the XmlSchemaImporter
XmlSchemas xsds = new XmlSchemas();
xsds.Add( xsd );
XmlSchemaImporter imp = new XmlSchemaImporter( xsds );
// System.CodeDom namespace for the XmlCodeExporter to put classes in
CodeNamespace ns = new CodeNamespace( "Generated" );
XmlCodeExporter exp = new XmlCodeExporter( ns );
// Iterate schema items (top-level elements only) and generate code for each
foreach ( XmlSchemaObject item in xsd.Items )
{
if ( item is XmlSchemaElement )
{
// Import the mapping first
XmlTypeMapping map = imp.ImportTypeMapping(
new XmlQualifiedName( ( ( XmlSchemaElement ) item ).Name,
xsd.TargetNamespace ) );
// Export the code finally
exp.ExportTypeMapping( map );
}
}
// Code generator to build code with.
ICodeGenerator generator = new CSharpCodeProvider().CreateGenerator();
// Generate untouched version
using ( StreamWriter sw = new StreamWriter( @"E:\Generated.Full.cs", false ) )
{
generator.GenerateCodeFromNamespace(
ns, sw, new CodeGeneratorOptions() );
}
The CodeNamespace variable ns contains a full CodeDom
hierarchy with all the types that were generated. Therefore, we can easily
customize their definitions by adding attributes, custom methods, etc. Even
converting those annoying public fields to properties, which is now much more robust
than the find-and-replace method I used on a previous life :):
+ FieldsToProperties method
static void FieldsToProperties(CodeNamespace ns)
{
// Copy the colletion to an array for safety. We will be
// changing this collection.
CodeTypeDeclaration[] types = new CodeTypeDeclaration[ns.Types.Count];
ns.Types.CopyTo( types, 0 );
// Turn fields into properties
foreach ( CodeTypeDeclaration type in types )
{
// Copy the colletion to an array for safety. We will be
// changing this collection.
CodeTypeMember[] members = new CodeTypeMember[type.Members.Count];
type.Members.CopyTo(members, 0);
foreach ( CodeTypeMember member in members )
{
// Process fields only.
if ( member is CodeMemberField )
{
CodeMemberProperty prop = new CodeMemberProperty();
prop.Name = member.Name;
// Rename field
member.Name = String.Concat( "_", member.Name.ToLower() );
prop.Attributes = member.Attributes;
prop.Type = ( ( CodeMemberField )member ).Type;
prop.HasGet = true;
prop.HasSet = true;
// Add get/set statements pointing to field.
prop.GetStatements.Add(
new CodeMethodReturnStatement(
new CodeFieldReferenceExpression( new CodeThisReferenceBLOCKED EXPRESSION,
member.Name ) ) );
prop.SetStatements.Add(
new CodeAssignStatement(
new CodeFieldReferenceExpression( new CodeThisReferenceBLOCKED EXPRESSION,
member.Name ),
new CodeArgumentReferenceExpression( "value" ) ) );
// Copy attributes from field to the property.
prop.CustomAttributes.AddRange(member.CustomAttributes);
member.CustomAttributes.Clear();
// Make field private
member.Attributes = MemberAttributes.Private;
// Finally add the property to the type
type.Members.Add( prop );
}
}
}
}
Now, simply passing the namespace generated by the previous code will result
in custom classes with properties instead of fields, with the appropriate
XmlSerialization attributes as generated initially. Below is the customized
complete schema for the Pubs database:
+ Pubs XSD schema customized.
namespace Lagash.Generated {
/// <remarks/>
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://www.lagash.com/schemas")]
[System.Xml.Serialization.XmlRootAttribute(Namespace="http://www.lagash.com/schemas", IsNullable=false)]
public class dsPubs {
/// <remarks/>
private dsPubsPublishers[] _items;
[System.Xml.Serialization.XmlElementAttribute("publishers")]
public dsPubsPublishers[] Items {
get {
return this._items;
}
set {
this._items = value;
}
}
}
/// <remarks/>
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://www.lagash.com/schemas")]
public class dsPubsPublishers {
/// <remarks/>
private string _pub_id;
/// <remarks/>
private string _pub_name;
/// <remarks/>
private string _city;
/// <remarks/>
private string _state;
/// <remarks/>
private string _country;
/// <remarks/>
private dsPubsPublishersTitles[] _titles;
public string pub_id {
get {
return this._pub_id;
}
set {
this._pub_id = value;
}
}
public string pub_name {
get {
return this._pub_name;
}
set {
this._pub_name = value;
}
}
public string city {
get {
return this._city;
}
set {
this._city = value;
}
}
public string state {
get {
return this._state;
}
set {
this._state = value;
}
}
public string country {
get {
return this._country;
}
set {
this._country = value;
}
}
[System.Xml.Serialization.XmlElementAttribute("titles")]
public dsPubsPublishersTitles[] titles {
get {
return this._titles;
}
set {
this._titles = value;
}
}
}
/// <remarks/>
[System.Xml.Serialization.XmlTypeAttribute(Namespace="http://www.lagash.com/schemas")]
public class dsPubsPublishersTitles {
/// <remarks/>
private string _title_id;
/// <remarks/>
private string _title;
/// <remarks/>
private string _type;
/// <remarks/>
private string _pub_id;
/// <remarks/>
private string _price;
/// <remarks/>
private string _advance;
/// <remarks/>
private string _royalty;
/// <remarks/>
private string _ytd_sales;
/// <remarks/>
private string _notes;
/// <remarks/>
private string _pubdate;
public string title_id {
get {
return this._title_id;
}
set {
this._title_id = value;
}
}
public string title {
get {
return this._title;
}
set {
this._title = value;
}
}
public string type {
get {
return this._type;
}
set {
this._type = value;
}
}
public string pub_id {
get {
return this._pub_id;
}
set {
this._pub_id = value;
}
}
public string price {
get {
return this._price;
}
set {
this._price = value;
}
}
public string advance {
get {
return this._advance;
}
set {
this._advance = value;
}
}
public string royalty {
get {
return this._royalty;
}
set {
this._royalty = value;
}
}
public string ytd_sales {
get {
return this._ytd_sales;
}
set {
this._ytd_sales = value;
}
}
public string notes {
get {
return this._notes;
}
set {
this._notes = value;
}
}
public string pubdate {
get {
return this._pubdate;
}
set {
this._pubdate = value;
}
}
}
}
+ Complete Pubs XSD
<?xml version="1.0" ?>
<xs:schema id="dsPubs" targetNamespace="http://www.lagash.com/schemas" xmlns:mstns="http://www.lagash.com/schemas"
xmlns="http://www.lagash.com/schemas" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"
attributeFormDefault="qualified" elementFormDefault="qualified">
<xs:element name="dsPubs" msdata:IsDataSet="true" msdata:EnforceConstraints="False">
<xs:complexType>
<xs:choice maxOccurs="unbounded">
<xs:element name="publishers">
<xs:complexType>
<xs:sequence>
<xs:element name="pub_id" type="xs:string" minOccurs="0" />
<xs:element name="pub_name" type="xs:string" minOccurs="0" />
<xs:element name="city" type="xs:string" minOccurs="0" />
<xs:element name="state" type="xs:string" minOccurs="0" />
<xs:element name="country" type="xs:string" minOccurs="0" />
<xs:element name="titles" minOccurs="0" maxOccurs="unbounded">
<xs:complexType>
<xs:sequence>
<xs:element name="title_id" type="xs:string" minOccurs="0" />
<xs:element name="title" type="xs:string" minOccurs="0" />
<xs:element name="type" type="xs:string" minOccurs="0" />
<xs:element name="pub_id" type="xs:string" minOccurs="0" />
<xs:element name="price" type="xs:string" minOccurs="0" />
<xs:element name="advance" type="xs:string" minOccurs="0" />
<xs:element name="royalty" type="xs:string" minOccurs="0" />
<xs:element name="ytd_sales" type="xs:string" minOccurs="0" />
<xs:element name="notes" type="xs:string" minOccurs="0" />
<xs:element name="pubdate" type="xs:string" minOccurs="0" />
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:choice>
</xs:complexType>
</xs:element>
</xs:schema>