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   How to: Access Data in SQL Query Results
   How to: Bind an XPCollection to a LookUp
   How to: Bind an XPCollection to Standard Controls
   How to: Bind an XPCollection to the DataGrid
   How to: Bind an XPCollection to the Grid
   How to: Build Complex Criteria
   How to: Build Simple Criteria
   How to: Change Inheritance Mapping
   How to: Connect to a SQL Server
   How to: Connect to SQL Azure
   How to: Connect XPO to a Database Other than MS SQL or MS Access
   How to: Control Automatic Saving of Objects when Editing in a Grid
   How to: Create an Aggregated Object
   How to: Delay Property Loading
   How to: Filter By DateTime Values
   How to: Filter Persistent Objects by Type
   How to: Handle Persistent Object Initialization
   How to: Implement a Custom Criteria Language Function Operator
   How to: Implement a Full-Text Search
   How to: Implement Custom Functions and Criteria in LINQ to XPO
   How to: Implement Many-to-Many Relationships
   How to: Implement One-to-One Relationships
   How to: Link Classes Located in Different Assemblies
   How to: Make a Class or Property Non-Persistent
   How to: Make XPCollection Create Objects of Specific Type when They are Created via Bound Controls
   How to: Map to Custom Tables (Views) and Columns
   How to: Obtain a Collection of Persistent Objects by a Set of Their IDs
   How to: Obtain a Collection of Persistent Objects for Processing
   How to: Persist a BLOB Field
   How to: Prevent Changes in a Persistent Object from being Automatically Committed
   How to: Restore Deleted Objects
   How to: Use Pageable Collections
   How to: Use Read-Only Persistent Properties
   How to: Use the ContainsOperator for Objects in a Many-to-Many Relationship
   How to: Validate an Object
   How to: Work with Structures
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How to: Restore Deleted Objects

Persistent objects, that are XPCustomObject or XPObject descendants, are not physically deleted from a database. Instead, these objects are only marked as deleted. XPO creates a GCRecord column in a database table for a given persistent class. When an object is deleted, a not-NULL value is assigned to the corresponding GCRecord field value. This is the Deferred Deletion feature, which enables the avoidance of constraint violations when deleting associated objects.

This example demonstrates how to restore deleted objects. To do this, a null (Nothing in VB.NET) value should be assigned to the corresponding GCRecord field value via the XPBaseObject.SetMemberValue method.

Note

When an object with Deferred Deletion enabled is deleted, it is removed from associated collections. Associations cannot be recreated automatically when you restore a deleted object. This behavior is by design, because the Deferred Deletion feature is not intended for object restoration, but for overcoming complex foreign index constraints at the database level.

Expanded Persistent Object Class Definition

First, define the Customer class. To provide for the automatic collection of changes by a Unit of Work, Simplified Property Syntax is used to code property setters.

Expanded Restoring Deleted Objects

Expanded See Also

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