/// <summary>
/// Creates a collection of tables found in the schema.
/// </summary>
/// <param name="xmlSchema">The schema that describes the data model.</param>
/// <returns>A list of TableSchema objects that describe the tables found in the data model schema.</returns>
private void FirstPass(XmlSchemaSet xmlSchemaSet)
{
// Scan through the schema set looking for table elements. These can either be defined at the root element for a standard
// schema or they can be found as choices of a special element describing a 'DataSet' for the Microsoft version of a
// schema.
foreach (XmlSchemaElement xmlSchemaElement in xmlSchemaSet.GlobalElements.Values)
{
// If the element read from the schema is the Microsoft DataSet element, then the tables are described as choices
// associated with an implicit complex type on that element.
if (ObjectSchema.IsDataSetElement(xmlSchemaElement))
{
// The tables are described as an choices of an implicit (nested) complex type.
if (xmlSchemaElement.SchemaType is XmlSchemaComplexType)
{
// The complex type describes the table.
XmlSchemaComplexType xmlSchemaComplexType = xmlSchemaElement.SchemaType as XmlSchemaComplexType;
// The data model is described as a set of one or more choices of tables.
if (xmlSchemaComplexType.Particle is XmlSchemaChoice)
{
// The data model is described as a set of choices. Each choice represents a table.
XmlSchemaChoice xmlSchemaChoice = xmlSchemaComplexType.Particle as XmlSchemaChoice;
// Create a table for each of the choices described in the complex type.
foreach (XmlSchemaObject choiceObject in xmlSchemaChoice.Items)
{
if (choiceObject is XmlSchemaElement)
{
XmlSchemaElement tableElement = choiceObject as XmlSchemaElement;
this.tableList.Add(tableElement.Name, new TableSchema(this, tableElement));
}
}
}
}
// The constraints describe the columns that are unique for a table.
foreach (XmlSchemaIdentityConstraint xmlSchemaIdentityConstraint in xmlSchemaElement.Constraints)
{
// This describes the columns that must be unique within a table.
if (xmlSchemaIdentityConstraint is XmlSchemaUnique)
{
XmlSchemaUnique xmlSchemaUnique = xmlSchemaIdentityConstraint as XmlSchemaUnique;
UniqueConstraintSchema uniqueConstraintSchema = new UniqueConstraintSchema(this, xmlSchemaUnique);
uniqueConstraintSchema.Table.Add(uniqueConstraintSchema);
}
}
}
}
}
/// <summary>
/// The foreign constraints can only be evaluated after all the tables, keys and unique constraints have been evaluated.
/// </summary>
/// <param name="xmlSchema"></param>
private void SecondPass(XmlSchemaSet xmlSchemaSet)
{
// This is the second pass through the schemas. Once the tables, keys and unique constraints have been evaluated,
// then the foreign constraints can be constructed and applied to the parent and child tables.
foreach (XmlSchemaElement xmlSchemaElement in xmlSchemaSet.GlobalElements.Values)
{
// Only the Microsoft DataSet element is evaluated for foreign keys.
if (ObjectSchema.IsDataSetElement(xmlSchemaElement))
{
// This will examine each of the constraints looking for a foreign key description.
foreach (XmlSchemaIdentityConstraint xmlSchemaIdentityConstraint in xmlSchemaElement.Constraints)
{
// Evaluate the foreign keys in the data model.
if (xmlSchemaIdentityConstraint is XmlSchemaKeyref)
{
// This object can be used as a foreign key constraint and, optionally, can be used to describe a
// parent/child relationship.
XmlSchemaKeyref xmlSchemaKeyref = xmlSchemaIdentityConstraint as XmlSchemaKeyref;
// This creates a foreign key.
ForeignKeyConstraintSchema foreignKeyConstraintSchema = new ForeignKeyConstraintSchema(this, xmlSchemaIdentityConstraint as XmlSchemaKeyref);
// Foreign constraint schemas are always added to the list of constraints on a table. They can also
// conditionally become the source for a relationship between two tables.
foreignKeyConstraintSchema.Table.Add(foreignKeyConstraintSchema);
// Unless specifically instructed to supress the relation, it will be created add added to both the
// parent and child tables as well as the data model.
XmlAttribute isConstraintOnlyAttribute = ObjectSchema.GetUnhandledAttribute(xmlSchemaIdentityConstraint, QualifiedName.ConstraintOnly);
if (isConstraintOnlyAttribute == null || !Convert.ToBoolean(isConstraintOnlyAttribute.Value))
{
RelationSchema relationSchema = new RelationSchema(this, xmlSchemaKeyref);
relationSchema.ParentTable.ChildRelations.Add(relationSchema.Name, relationSchema);
relationSchema.ChildTable.ParentRelations.Add(relationSchema.Name, relationSchema);
this.Relations.Add(relationSchema.Name, relationSchema);
}
}
}
}
}
}
