B.1 codegen Namespace

The codegen namespace gives you fine-grained control of a typed DataSet. By adding codegen attributes, you can configure the names that are used for methods, properties, relations, and constraints. When using the codegen namespace, it should be imported as shown:

<xs:schema id="DataSetName" xmlns="" 
    xmlns:xs="http://www.w3.org/2001/XMLSchema"
    xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"
    xmlns:codegen="urn:schemas-microsoft-com:xml-msprop" >

codegen attributes configure the names used in strongly typed DataSet objects. They do not have any effect on the functionality of the generated DataSet class.

Table B-1 indicates where the various codegen attributes can be used and what they accomplish. Table B-2 briefly describes each attribute.

Table B-1. codegen attribute use

Typed DataSet object/method/event	Default name	codegen attribute
DataTable	TableNameDataTable	typedPlural
DataTable Methods	NewTableNameRow AddTableNameRow DeleteTableNameRow	typedName
DataRowCollection	TableName	typedPlural
DataRow	TableNameRow	typedName
DataColumn	DataTable.ColumnNameColumn DataRow.ColumnName	typedName
Property	PropertyName	typedName
Child Accessor	GetChildTableNameRows	typedChildren
Parent Accessor	TableNameRow	typedParent
DataSet Events	TableNameRowChangeEvent TableNameRowChangeEventHandler	typedName

Table B-2. codegen atttributes

Attribute	Description
typedName	Name of the object in the generated class.
typedPlural	The name of the object in a collection of objects. For example, if you specify Category for typedName and Categories for typedPlural, you generate a Categories collection and a Category row (instead of a CategoriesRow).
typedParent	Name of the object when referred to in a parent relationship. Typed datasets automatically generate methods that provide access to parent and child rows. For example, if you specify Category for the typedParent of an order record, use a Order.Category( ) method instead of Order.GetCategoriesRow( ).
typedChildren	Name of the method to return objects from a child relationship. For example, if you specify Order for the typedChild of a category record, use a Category.Orders( ) method instead of Category.GetOrdersRows( ).
nullValue	Indicates the behavior when null values are encountered. See Table B-3 for possible values.

Finally, Table B-3 identifies possible values for the nullValue attribute.

Table B-3. Values for nullValue

Value	Description
[Replacement Value]	Specifies a value to be returned. For example, use nullValue="0" to set null integer fields to 0.
_throw	Throws an exception when a null value is encountered. This is the default.
_null	Returns a null reference (or throws an exception if a primitive type is encountered).
_empty	For strings, returns String.Empty. For objects, returns the default uninitialized object (created from the zero-parameter constructor). If a primitive type is encountered, ADO.NET generates an exception.