A relationship class object the is stored in memory.
MemoryRelationshipClass is a non-creatable object. References to non-creatable objects must be obtained through other objects.
| Interfaces | Description |
|---|---|
| IDataset | Provides access to members that supply dataset information. |
| IRelationshipClass | Provides access to members that return information about the relationship class, create relationships, relationship rules and get related objects. |
| IRelationshipClass2 | Provides access to members that get related object row pairs within a query filter specification. |
A MemoryRelationshipClass is a type of RelationshipClass in which the origin and destination classes can be from different workspaces and do not need to persist in a geodatabase. For example, the origin class can represent a shapefile while the destination class can represent a table in a personal geodatabase. It is stored in memory instead of within a geodatabase like other RelationshipClasses. You can use the MemoryRelationshipClassName object to save and restore a MemoryRelationshipClass.
To create a Relate in ArcMap, a MemoryRelationshipClass must first be created and then assigned to a Layer or StandaloneTable using the IRelationshipClassCollectionEdit interface.
MemoryRelationshipClasses are simple (non-composite), non-attributed RelationshipClasses that do not support relationship rules. When initialized, the notification type is automatically set to esriRelNotificationNone.
MemoryRelationshipClass inherits from a RelationshipClass and although it implements the same interfaces, not all properties and methods are supported. The following is a review of each of these inheritied interfaces and describes which properties and methods behave differently or are not supported with MemoryRelationshipClasses.
IRelationshipClass
The table below describes how the methods and properties from IRelationshipClass are implemented by a MemoryRelationshipClass:
|
Member |
Behavior with a MemoryRelationshipClass |
|
DestinationClass |
Returns the OriginForeignClass object specified in the IMemoryRelationshipClassFactory::Open method. |
|
OriginClass |
Returns the OriginPrimaryClass object specified in the IMemoryRelationshipClassFactory::Open method. |
|
DestinationForeignKey |
Returns an empty string since a MemoryRelationshipClass is not attributed. |
|
DestinationPrimaryKey |
Returns an empty string since a MemoryRelationshipClass is not attributed. |
|
FeatureDataSet |
Property is not supported. An error will be returned if you try to use this property. |
|
IsAttributed |
Returns False since it can't be attributed. |
|
IsComposite |
Returns False since it can't be composite. |
|
Notification |
Returns esriRelNotificationNone. |
|
RelationshipClassID |
Returns -1. This does not need to be set to a meaningful value since a MemoryRelationshipClass is not stored in a geodatabase |
|
RelationshipRules |
Property is not supported. An error will be returned if you try to use this property. |
|
AddRelationshipRule |
Method is not supported. An error will be returned if you try to use this method. |
|
CreateRelationship |
Method is not supported. An error will be returned if you try to use this method. |
|
DeleteRelationship |
Method is not supported. An error will be returned if you try to use this method. |
|
DeleteRelationshipRule |
Method is not supported. An error will be returned if you try to use this method. |
|
DeleteRelationshipsforObject |
Method is not supported. An error will be returned if you try to use this method. |
|
DeleteRelationshipsforObjectSet |
Method is not supported. An error will be returned if you try to use this method. |
|
GetRelationship |
Method is not supported. An error will be returned if you try to use this method. |
|
GetRelationshipForObject |
Method is not supported. An error will be returned if you try to use this method. |
|
GetRelationshipForObjectSet |
Method is not supported. An error will be returned if you try to use this method. |
Since the origin and destination classes may belong to different workspaces, the methods in IRelationshipClass that involve editing are not available. The properties and methods of IRelationshipClass that are not listed in the table behave the same way with MemoryRelationshipClasses and they do with other RelationshipClasses.
IDataset
The table below describes how the methods and properties from IDataset are implemented by a MemoryRelationshipClass:
|
Member |
Behavior with a MemoryRelationshipClass |
|
BrowseName |
You can get, but not set the BrowseName. The BrowseName will be the name given the MemoryRelationshipClass when initialized. If you try to set it an error is returned. |
|
Category |
Returns the string "Memory relationship class" |
|
FullName |
Returns a MemoryRelationshipClassName object. |
|
Name |
Like BrowseName, returns the name given the MemoryRelationshipClass when initialized |
|
PropertySet |
Property is not supported. An error will be returned if you try to use this property. |
|
Subsets |
Returns a Null or a nothing object in Visual Basic. |
|
Type |
Returns esriDTRelationshipClass. |
|
Workspace |
Returns a Null or a nothing object in Visual Basic. |
|
CanCopy |
Returns False indicating that it can't be copied. |
|
CanDelete |
Returns False indicating that it can't be deleted. |
|
CanRename |
Returns true indicating that it can be renamed. |
|
Copy |
Method is not supported. An error will be returned if you try to use this method. |
|
Delete |
Method is not supported. An error will be returned if you try to use this method. |
|
Rename |
Renames the MemoryRelationshipClass to the name given. |
IRelationshipClass2
The IRelationshipClass2 interface provides methods that allow a QueryFilter to be applied to the group of rows that match a specified group of rows in the related table. For example, instead of returning all counties in the state of California, a QueryFilter can be used to limit the California counties returned to just those with a population of over 1 million.
MemoryRelationshipClassName CoClass | MemoryRelationshipClassFactory CoClass