/// <summary>
/// Create a foreign key constraint on two tables.
/// </summary>
/// <param name="dataModelSchema">The parent data model schema.</param>
/// <param name="xmlSchemaKeyref">The XmlSchema object that describes the foreignn key relation.</param>
public RelationSchema(DataModelSchema dataModelSchema, XmlSchemaKeyref xmlSchemaKeyref)
{
// Initialize the object.
this.name = xmlSchemaKeyref.Name;
// This will search through each of the tables looking for the parent and child components of the relation.
foreach (KeyValuePair <string, TableSchema> keyValuePair in dataModelSchema.Tables)
{
ConstraintSchema constraintSchema;
// This is the parent component of the relation.
if (keyValuePair.Value.Constraints.TryGetValue(xmlSchemaKeyref.Refer.Name, out constraintSchema))
{
UniqueConstraintSchema uniqueConstraintSchema = constraintSchema as UniqueConstraintSchema;
this.parentColumns = uniqueConstraintSchema.Columns;
this.parentTable = uniqueConstraintSchema.Table;
this.parentKeyConstraint = uniqueConstraintSchema;
}
// This is the child part of the relation.
if (keyValuePair.Value.Constraints.TryGetValue(xmlSchemaKeyref.Name, out constraintSchema))
{
ForeignKeyConstraintSchema foreignKeyConstraintSchema = constraintSchema as ForeignKeyConstraintSchema;
this.childTable = foreignKeyConstraintSchema.Table;
this.childColumns = foreignKeyConstraintSchema.Columns;
this.childKeyConstraint = foreignKeyConstraintSchema;
}
}
}
/// <summary>
/// Creates an array of values from a unique constraint that can be used for finding records.
/// </summary>
/// <param name="uniqueConstraintSchema">A description of a unique constraint.</param>
/// <returns>An array of expressions that can be used as a key for finding records in a table.</returns>
public CodeExpression[] CreateKey(UniqueConstraintSchema uniqueConstraintSchema)
{
// This will cycle through all the foreign and simple parameters looking for any columns that match up to the child
// columns of the constraint. When found, they are placed in the array in the proper order to match up against the
// given unique constraint.
List <CodeExpression> keys = new List <CodeExpression>();
foreach (ColumnSchema uniqueColumn in uniqueConstraintSchema.Columns)
{
foreach (KeyValuePair <string, ExternalParameterItem> parameterPair in this.ExternalParameterItems)
{
// This correlates the unique constraint columns with the variables that have been created in the method to
// hold the key values from the foreign tables. These variables exist outside of the conditional logic that
// finds the parent row, so if the parent key is null, these values will also be null. However, since they're
// still declared, they can be used to construct keys, which is useful when they're optional values.
if (parameterPair.Value is ForeignKeyConstraintParameterItem)
{
ForeignKeyConstraintParameterItem foreignKeyConstraintParameterItem = parameterPair.Value as ForeignKeyConstraintParameterItem;
ForeignKeyConstraintSchema foreignKeyConstraintSchema = foreignKeyConstraintParameterItem.ForeignKeyConstraintSchema;
for (int columnIndex = 0; columnIndex < foreignKeyConstraintSchema.Columns.Length; columnIndex++)
{
if (uniqueColumn == foreignKeyConstraintSchema.Columns[columnIndex])
{
foreach (ForeignKeyVariableItem foreignKeyVariableItem in foreignKeyConstraintParameterItem.ForeignKeyVariables)
{
if (foreignKeyConstraintSchema.Columns[columnIndex] == foreignKeyVariableItem.ColumnSchema)
{
keys.Add(foreignKeyVariableItem.Expression);
}
}
}
}
}
// This will match the columns described in the simple parameters to the columns in the unique constraint.
if (parameterPair.Value is SimpleParameterItem)
{
SimpleParameterItem simpleParameterItem = parameterPair.Value as SimpleParameterItem;
if (uniqueColumn == simpleParameterItem.ColumnSchema)
{
keys.Add(new CodeVariableReferenceExpression(CommonConversion.ToCamelCase(simpleParameterItem.ColumnSchema.Name)));
}
}
}
}
// This array can be used as a key to find the record in a table.
return(keys.ToArray());
}
/// <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);
}
}
}
}
}
}
/// <summary>
/// Creates the element that describes a foreign constraint.
/// </summary>
/// <param name="foreignConstraintSchema">A description of a foreign constraint.</param>
/// <returns>An element that can be used in an XML Schema document to describe a foreign constraint.</returns>
private static XElement CreateForeignKey(ForeignKeyConstraintSchema foreignKeyConstraintSchema)
{
// <xs:keyref name="FK_Entity_AccessControl" refer="EntityKey" msprop:rel_Generator_UserRelationName="FK_Entity_AccessControl"
// msprop:rel_Generator_RelationVarName="relationFK_Entity_AccessControl" msprop:rel_Generator_UserChildTable="AccessControl"
// msprop:rel_Generator_UserParentTable="Entity" msprop:rel_Generator_ParentPropName="EntityRow"
// msprop:rel_Generator_ChildPropName="GetAccessControlRows">
// <xs:selector xpath=".//mstns:AccessControl" />
// <xs:field xpath="mstns:EntityId" />
// </xs:keyref>
XElement foreignElement = new XElement(
SchemaScrubber.xs + "keyref",
new XAttribute("name", foreignKeyConstraintSchema.Name),
new XAttribute("refer", foreignKeyConstraintSchema.RelatedTable.GetUniqueConstraint(foreignKeyConstraintSchema.RelatedColumns).Name),
new XAttribute(SchemaScrubber.msprop + "rel_Generator_UserRelationName", foreignKeyConstraintSchema.Name),
new XAttribute(SchemaScrubber.msprop + "rel_Generator_RelationVarName", String.Format("relation{0}", foreignKeyConstraintSchema.Name)),
new XAttribute(SchemaScrubber.msprop + "rel_Generator_UserChildTable", foreignKeyConstraintSchema.Table.Name),
new XAttribute(SchemaScrubber.msprop + "rel_Generator_UserParentTable", foreignKeyConstraintSchema.RelatedTable.Name),
new XAttribute(SchemaScrubber.msprop + "rel_Generator_ParentPropName", String.Format("{0}Row", foreignKeyConstraintSchema.RelatedTable.Name)),
new XAttribute(SchemaScrubber.msprop + "rel_Generator_ChildPropName", String.Format("Get{0}Rows", foreignKeyConstraintSchema.Table.Name)));
foreignElement.Add(
new XElement(
SchemaScrubber.xs + "selector",
new XAttribute("xpath", String.Format(".//mstns:{0}", foreignKeyConstraintSchema.Table.Name))));
foreach (ColumnSchema columnSchema in foreignKeyConstraintSchema.Columns)
{
foreignElement.Add(
new XElement(
SchemaScrubber.xs + "field",
new XAttribute("xpath", String.Format("mstns:{0}", columnSchema.Name))));
}
// This describes a foreign constraint on a table.
return(foreignElement);
}
