imtdb::IDependentMetaInfoController

Manages cascading metadata updates when related objects are deleted. More...

#include <IDependentMetaInfoController.h>

Inherits istd::IPolymorphic.

Inherited by imtdb::CSqlDatabaseDocumentDelegateComp [virtual].

Classes
struct	DependentMetaInfo
	Information for updating dependent metadata fields. More...
struct	MetaFieldCleanupPlan
	Plan for cleaning up metadata fields when referenced objects are deleted. More...

Public Member Functions
virtual bool	UpdateDependentMetaInfo (const DependentMetaInfo &metaInfo) const =0
	Updates dependent metadata fields to reflect changes in referenced objects.
virtual bool	ClearDependentMetaInfo (const MetaFieldCleanupPlan &metaInfo) const =0
	Clears metadata fields that reference deleted objects.

Detailed Description

Manages cascading metadata updates when related objects are deleted.

IDependentMetaInfoController maintains referential integrity in JSON-based metadata when referenced objects are deleted. It identifies and cleans up dependent metadata fields that reference deleted objects, preventing stale references.

The Problem

Consider this scenario:

• Customer objects stored in customers table
• Order objects stored in orders table with metadata: json { "CustomerId": "cust-123", "CustomerName": "John Doe", "CustomerEmail": "john@example.com" }
• When Customer "cust-123" is deleted, the Order metadata has stale references

The Solution

The controller:

1. Observes deletion events in source collections (Customers)
2. Identifies dependent collections (Orders) with references
3. Finds objects with metadata referencing deleted IDs
4. Clears or nullifies the dependent metadata fields
5. Updates timestamps and audit trails

Cleanup Workflow

* 1. Delete Customer "cust-123"
*    ↓
* 2. Controller identifies dependent metadata:
*    - Table: orders
*    - Key: CustomerId
*    - Dependent fields: CustomerName, CustomerEmail
*    ↓
* 3. Find orders with CustomerId = "cust-123"
*    ↓
* 4. Update metadata:
*    {
*      "CustomerId": null,         // Clear reference
*      "CustomerName": null,       // Clear dependent field
*      "CustomerEmail": null       // Clear dependent field
*    }
*    ↓
* 5. Update LastModified timestamp
* 

Usage Example

auto controller = acf::CreateComponent<CDependentTableMetaInfoControllerComp>();
 
// Configure which fields depend on which references
controller->AddDependentMapping("orders", "CustomerId", 
                                 QStringList{"CustomerName", "CustomerEmail"});
 
// When deleting customers
imtbase::ICollectionInfo::Ids deletedCustomerIds = {"cust-123", "cust-456"};
 
MetaFieldCleanupPlan plan;
plan.objectIds = deletedCustomerIds;
plan.dependentKey = "CustomerId";
plan.metaInfoIds = QStringList{"CustomerName", "CustomerEmail"};
 
controller->ClearDependentMetaInfo(plan);
// All orders referencing deleted customers now have cleaned metadata

Note

Cleanup is typically automatic via Observer pattern

Works with JSON/JSONB metadata columns

See also

CDependentTableMetaInfoControllerComp for implementation

CSqlDatabaseDocumentDelegateComp for integration

Definition at line 95 of file IDependentMetaInfoController.h.

Member Function Documentation

ClearDependentMetaInfo()

virtual bool imtdb::IDependentMetaInfoController::ClearDependentMetaInfo ( const MetaFieldCleanupPlan &  metaInfo ) const

pure virtual

Clears metadata fields that reference deleted objects.

When objects are deleted, this method finds all dependent objects that have metadata referencing the deleted IDs and clears the relevant fields.

Parameters

metaInfo

Describes which objects were deleted and what fields to clean

Returns

true if cleanup succeeded, false on error

Process:

1. Find all objects where metadata[dependentKey] is in objectIds
2. For each found object:
   • Set metadata[dependentKey] = null
   • For each field in metaInfoIds: set metadata[field] = null
   • Update LastModified timestamp

// Customers "cust-123" and "cust-456" were deleted
MetaFieldCleanupPlan plan;
plan.objectIds = {"cust-123", "cust-456"};
plan.dependentKey = "CustomerId";
plan.metaInfoIds = {"CustomerName", "CustomerEmail"};
 
controller->ClearDependentMetaInfo(plan);
// All orders with CustomerId in deleted list now have cleared metadata

Note

This maintains referential integrity in JSON metadata

Typically called automatically when objects are deleted

See also

UpdateDependentMetaInfo()

UpdateDependentMetaInfo()

virtual bool imtdb::IDependentMetaInfoController::UpdateDependentMetaInfo ( const DependentMetaInfo &  metaInfo ) const

pure virtual

Updates dependent metadata fields to reflect changes in referenced objects.

When a referenced object changes (e.g., Customer renamed), this method updates all dependent metadata that includes derived fields from that object.

Parameters

metaInfo

Describes which object's metadata to update and what values to set

Returns

true if update succeeded, false on error

Example use case:

• Customer "cust-123" renamed from "John Doe" to "John Smith"
• Update all Order metadata where CustomerId = "cust-123"
• Set CustomerName = "John Smith"

DependentMetaInfo update;
update.objectId = "order-789";
update.dependentKey = "CustomerId";
update.metaInfoIds = QStringList{"CustomerName"};
update.metaInfoValues = QStringList{"John Smith"};
 
controller->UpdateDependentMetaInfo(update);

See also

ClearDependentMetaInfo()