Editing OpenSimulator Internals/Walkthroughs/Avatar Derezzes Object

= OpenSimulator Internals/Walkthroughs/Avatar Derezzes Object =

== Overview ==

Traces what happens in code, connectors, and database when an avatar takes an object from the world into inventory (derez), or deletes it. Uses the box-with-notecard from [[OpenSimulator Internals/Walkthroughs/Avatar Rezzes Box]] as the concrete example.

This is a concrete instance of [[OpenSimulator Internals/Walkthroughs/Avatar Acquires Inventory]]. Read that page for the full code path.

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== Case 1: Take (own object, no-copy) ==

Avatar right-clicks the box and selects Take.

=== 1. Viewer Sends DeRezObject ===

# Viewer sends DeRezObject packet with action=Take, objectLocalID=box local ID.
# Scene.DeRezObjects() validates permissions (CanTakeObject).
# Calls IInventoryAccessModule.CopyToInventory(DeRezAction.Take, folderID, [boxSOG], client, false).

=== 2. Object Serialised ===

BasicInventoryAccessModule.CopyBundleToInventory():
# Serialises box SOG to XML: SceneObjectSerializer.ToOriginalXmlFormat().
#* XML includes: prim data, shape, permissions, position, rotation, task inventory (the notecard reference is embedded in the XML as a primitems-equivalent block).
# Creates asset: AssetService.Store() -- new UUID, AssetType.Object, data = XML bytes.
# CreateItemForObject(Take): determines folder (original FromFolderID if owner taking back own item).
# AddPermissions(): same-owner path, preserves current permissions.
# Scene.AddInventoryItem(): InventoryService.AddItem() -- writes inventoryitems row.
# Sends SendInventoryItemCreateUpdate() to client.

; DB writes:
* assets -- INSERT: new object XML asset UUID
* inventoryitems -- INSERT: new item in Object folder (or original folder)

=== 3. Object Removed from Scene ===

DoPostRezWhenFromItem():
* Box was no-copy: InventoryService.DeleteItems() -- removes original inventoryitems row.

Scene.DeleteSceneObject(boxSOG, false):
* RemoveScriptInstances() -- no-op (no scripts).
* Removes physics actor.
* UnlinkSceneObject() -- removes from scene graph.
* SimulationDataService.RemoveObject(boxUUID, regionID).

; DB writes:
* inventoryitems -- DELETE: original no-copy item
* prims -- DELETE: box prim row
* primshapes -- DELETE: box shape row
* primitems -- DELETE: notecard task inventory row

=== 4. DB State After ===

Region database:
* prims: box row gone.
* primshapes: box shape row gone.
* primitems: notecard task inventory row gone.

Robust database:
* assets: new object XML asset (contains the notecard reference inside the serialised XML).
* inventoryitems: new item pointing to the new asset UUID.
* The notecard asset itself remains in assets table -- assets are never deleted on take.

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== Case 2: Take Copy (copyable object) ==

Avatar right-clicks and selects Take Copy.

Same serialise-and-store process as above, but:
* DoPostRezWhenFromItem() does NOT delete the original inventory item (item has Copy permission).
* Scene.DeRezObjects() does NOT call DeleteSceneObject() -- object stays in world.

; DB writes:
* assets -- INSERT: new object XML asset
* inventoryitems -- INSERT: new item in Object folder

Region DB unchanged. The box stays in the world.

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== Case 3: Delete (move to Trash) ==

Avatar right-clicks and selects Delete.

Calls CopyToInventory(DeRezAction.Delete):
* Destination folder: Trash (FolderType.Trash) if own object, Lost and Found if another's.
* Same serialise-and-store process.
* Scene.DeleteSceneObject() removes from scene and region DB.

; DB writes:
* assets -- INSERT: serialised object XML
* inventoryitems -- INSERT: item in Trash
* prims/primshapes/primitems -- DELETE

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== Key DB Tables Affected ==

{| class="wikitable"
! Table !! Take (no-copy) !! Take Copy !! Delete
|-
| assets || INSERT (new) || INSERT (new) || INSERT (new)
|-
| inventoryitems || INSERT new + DELETE old || INSERT new only || INSERT (Trash)
|-
| prims || DELETE || unchanged || DELETE
|-
| primshapes || DELETE || unchanged || DELETE
|-
| primitems || DELETE || unchanged || DELETE
|}

Note: asset rows are never deleted from the assets table by any of these operations. Assets accumulate. Cleanup is a separate administrative operation outside normal simulator operation.

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== What Happens to the Notecard Inside ==

The notecard was task inventory of the box (a primitems row). When the box is taken or deleted:

* The primitems row is deleted from the region DB.
* The notecard asset (text content) remains in the assets table -- it is referenced by assetID in the serialised object XML.
* When the box is later rezzed from inventory, the XML is deserialised and the notecard reappears as task inventory -- it is re-fetched from assets by assetID.

The notecard is not duplicated into the avatar's personal inventory (inventoryitems). It stays embedded in the object asset.

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== See Also ==

* [[OpenSimulator Internals/Walkthroughs]]
* [[OpenSimulator Internals/Walkthroughs/Avatar Acquires Inventory]]
* [[OpenSimulator Internals/Walkthroughs/Avatar Rezzes Box]]
* [[OpenSimulator Internals/Walkthroughs/Avatar Rezzes Inventory]]
* [[OpenSimulator Internals/Walkthroughs/Garbage Collection]]
* [[OpenSimulator Internals/Code Map/InventoryAccessModule]]
* [[OpenSimulator Internals/Databases]]