Articolo
11/18/2011

InheritanceMappingAttribute Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Maps an inheritance hierarchy in a LINQ to SQL application.

Inheritance Hierarchy

System.Object
System.Attribute
System.Data.Linq.Mapping.InheritanceMappingAttribute

Namespace: System.Data.Linq.Mapping
Assembly: System.Data.Linq (in System.Data.Linq.dll)

Syntax

'Declaration
<AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple := True, Inherited := False)> _
Public NotInheritable Class InheritanceMappingAttribute _
    Inherits Attribute

[AttributeUsageAttribute(AttributeTargets.Class, AllowMultiple = true, Inherited = false)]
public sealed class InheritanceMappingAttribute : Attribute

The InheritanceMappingAttribute type exposes the following members.

Constructors

	Name	Description
	InheritanceMappingAttribute	Initializes a new instance of the InheritanceMappingAttribute class.

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Properties

	Name	Description
	Code	Gets or sets the discriminator code value in a mapped inheritance hierarchy.
	IsDefault	Gets or sets whether an object of this type in instantiated when the discriminator value does not match a specified value.
	Type	Gets or sets the type of the class in the hierarchy.

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Methods

	Name	Description
	Equals	Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Returns the hash code for this instance. (Inherited from Attribute.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	Match	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Remarks

One InheritanceMappingAttribute is specified per mapped class.

Note the following when you map inheritance hierarchies:

All classes in a hierarchy must be mapped to a single table.
The table for an inheritance hierarchy must be declared on the mapped type that is at the top of the hierarchy. You cannot specify the table or mapping attributes in a class that is derived from the top class.
You can use an interface in a hierarchy, but LINQ does not map it.
You can skip a class in the hierarchy when you map classes, but you can query against mapped classes only.

For correct materialization, discriminator code values must be unique and match the values in the database. A row with a discriminator code value that does not exactly match (even by casing) instantiates the class by using IsDefault set to true.

Topic	Location
Inheritance Support (LINQ to SQL)	LINQ to SQL
Attribute-Based Mapping (LINQ to SQL)	LINQ to SQL
How to: Map Inheritance Hierarchies (LINQ to SQL)	LINQ to SQL
Inheritance Support (LINQ to SQL)	LINQ to SQL
Attribute-Based Mapping (LINQ to SQL)	LINQ to SQL
How to: Map Inheritance Hierarchies (LINQ to SQL)	LINQ to SQL

Version Information

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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