From asset to a player's hand¶

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This isn't a reference — it's one short story. The goal: in 10 minutes, see with your own eyes how an item travels the whole way from a Data Asset to a sword in a character's hand, without writing a single line of inventory code yourself. Every example below already lives in the plugin itself (Plugins/InventorySystemDemo/Content/Demo/Items/), so you can open the editor and repeat each step literally — with no asset of your own.

If after this page you want to understand "but why this way" — the chapters at the end cover each step in detail.

The cast¶

Seven items are already created in Plugins/InventorySystemDemo/Content/Demo/Items/ — together they show every combination of the shipped fragments (what a fragment is, and why an item is a set of fragments rather than a class — 01 — Core Concepts):

Asset	What it is	What it's made of
`DA_IronSword`	Iron Sword	`Equippable` + `Durability`
`DA_WoodenShield`	Wooden Shield	`Equippable` (other hand) + `Durability`
`DA_KnightHelmet`	Knight's Helmet	`Equippable` (head) + `Durability` — wears not from use
`DA_Torch`	Torch	`Equippable` + `Durability` + `Consumable` — all three at once
`DA_HealthPotion`	Health Potion	`Stackable` + `Consumable`
`DA_CopperOre`	Copper Ore	`Stackable` + `Weight`
`DA_AncientRelic`	Ancient Relic	no fragments at all

None of them has a class of its own — neither C++ nor Blueprint. It's just data on an asset. That's why all the difference in behaviour between the sword, the shield, the helmet, the torch, the potion, the ore and the relic is visible below in a few lines per item, not in seven separate classes.

Step 0 — the character needs a backpack¶

Before you can pick anything up, the player must have an Inventory component (and, if you plan to equip anything — Equipment). The fastest way the first time requires no code and no edit to the character Blueprint:

Project Settings → Game → Inventory System:

Setting	Value for this story
`Auto Create Player Inventory`	✅
`Auto Create Player Equipment`	✅
`Default Equipment Slots`	`Equipment.Slot.Weapon.Main`

Done. The plugin creates both components on every player's PlayerState as soon as they appear in the game. For a permanent project the component is usually added by hand to a specific character — 02 — Setup explains why auto-creation is off by default and when to turn it on deliberately.

Step 1 — the sword appears in the world¶

Place an AISDemoItemPickup actor in the level and set its Item Definition field to DA_IronSword. That's it — no separate Blueprint for "a sword lying on the ground" is needed: the same Item Pickup class serves any item in the game.

The mesh the player sees, the plugin takes from the PickupMesh field of DA_IronSword itself (category Item|World in Details) — automatically, at game start. If PickupMesh isn't set, the actor still works (it can be picked up), it just stays invisible on the ground. That's why the pickup mesh: yes / no line in the debug panel (DemoInvOverlay) is worth checking for a newly created item before you place it in the world — it says directly whether the player will see anything on the ground.

Step 2 — the player picks up the sword¶

Interaction (a key, a trace under the crosshair, a trigger — that's your project's logic) calls one method — on the player's inventory, not on the pickup:

Inventory->TryCollect(Pickup);

Why this way, and not Pickup->TryCollect(...) directly: the pickup has no network connection of its own (nobody has "picked it up" yet), so it can't forward a client's request to the server. The player's inventory has a connection, so the request goes through it — the same Try* as everywhere in the plugin, called from anywhere and figuring out where it should actually run. The developer doesn't have to think about it.

The method finds where to put it and places the item in the same state it was in on the ground (if the sword was picked up damaged rather than freshly placed, the damage is kept). The pickup is destroyed (the default behaviour), and the sword now sits in an inventory slot.

Check it without a single line of code: open DemoInvOverlay (the I key or the console command of the same name), type iron into the GIVE ITEM field, press Give — and that same DA_IronSword ends up in slot 0. This is exactly the same action TryCollect performs in the game: the panel just lets you click it, rather than run across the level to test.

Step 3 — the sword ends up in the hand¶

That's all the magic — and it has exactly zero lines of code on your side. On DA_IronSword, on the Equippable fragment, two fields are filled in (category Equippable|Visuals):

Field	Value in the example
`EquippedActorClass`	the sword actor's class (a Blueprint with a static mesh)
`AttachSocketName`	`hand_rSocket` (or any socket on your skeleton)

You call — from a UI button, a hotkey, anywhere:

Equipment->TryEquipFromInventorySlot(0);

…and the equipment component creates the EquippedActorClass itself and attaches it to the named socket of the character — separately on each machine. This isn't replicated, so a sword in the hand costs no network traffic beyond the fact that "this slot is occupied".

If no socket is set, the actor attaches to the character's root rather than disappearing; on a bare DefaultPawn with no skeletal mesh that's what happens, and for testing the logic that's perfectly fine.

The same step without code: in DemoInvOverlay, on the sword's row in CONTENTS — an Equip button. Click, and that same TryEquipFromInventorySlot fires from the mouse; the EQUIPMENT panel immediately shows an occupied Weapon.Main slot.

If EquippedActorClass is left empty, the item still equips (the slot is occupied, GetTotalStatValue counts its bonuses) — nothing just appears in the hand. Useful for a ring that only grants stats, or for armour already baked into the character mesh.

And the shield in the other hand — two equipped items at once¶

DA_WoodenShield is the same recipe as the sword (Equippable + Durability), only EquipmentSlot points at Equipment.Slot.Weapon.Offhand instead of Weapon.Main. The same call, a different slot:

Equipment->TryEquipFromInventorySlot(1); // if the shield is in slot 1

Now the character holds both items at once — one in each hand, each attached to its own socket independently. There's no special "weapon-shield pair" handling in the plugin: Weapon.Main and Weapon.Offhand are just two different entries in the equipment component's AvailableSlots, and each is handled the same way as the single slot in the sword example.

Without code: the Equip button on the shield's row in DemoInvOverlay — just like for the sword.

And the helmet on the head — the same `Durability`, different wear logic¶

DA_KnightHelmet is the third item worn at once (Equipment.Slot.Armor.Head, a third independent slot alongside the two hands), and at first glance the same recipe: Equippable + Durability. The difference is one number.

The sword and shield have DurabilityPerUse greater than zero: durability is spent when the item is explicitly used. The helmet has DurabilityPerUse = 0 — durability isn't spent on its own at all. This isn't an oversight but documented behaviour: nobody "uses" armour with a click, it wears from the character being hit. So the project's combat code deducts it directly from the instance itself, not through the fragment:

HelmetInstance->ModifyStatValue(ISDemoTags::Stat_Durability, -DamageTaken);

(Durability->Repair() won't do here — it only restores durability, and a negative value means "repair fully" to it, not "take away". For external damage it's ModifyStatValue on the instance, with a negative delta.)

…when the character takes a hit — not relying on TryUseItem, which makes no sense for armour at all. MaxDurability = 60 here is the same kind of number as on the sword or shield — it counts "how many hits it survives", not "how many times it was clicked".

Without code: the Equip button on the helmet's row in DemoInvOverlay, like the rest. There won't be a Use button — the helmet doesn't need a Consumable fragment, and without one IsUsable() for armour returns false, just like for copper ore.

And now the torch — all three fragments at once¶

DA_Torch has the same Equippable as the sword (it appears in the hand the same way), plus Durability (a "fuel" reserve) and Consumable (spent on use). No separate code was needed for this — just a third entry in the fragment array.

Inventory->TryUseItem(SlotIndex, Instigator);

The same call any item with a "Use" button uses: the fragments decide what it means for the torch specifically (spend a charge, reduce the fuel reserve). The inventory itself knows nothing special about the torch.

Without code: the Use button on the torch's row in DemoInvOverlay.

And the potion — no equipping at all¶

DA_HealthPotion (Stackable + Consumable) never ends up in EQUIPMENT — it has no Equippable fragment, so the debug panel doesn't even show an Equip button for it (the "does it have the fragment" check hides it automatically, for any item). Use is the same TryUseItem, only this time the stack decreases by one instead of waiting for wear.

And the copper ore — cargo with no action at all¶

DA_CopperOre (Stackable + Weight) has no Use button at all — it has no Consumable, so IsUsable() returns false, and the debug panel hides the button just as it hid Equip for the potion. The only thing this ore does is take a slot in a stack (up to 99 copies in one slot) and add weight to the inventory's GetCurrentWeight().

This is a deliberately boring example: not every item has to do something. A crafting material, currency, raw materials — all of these are legitimate items with empty behaviour, and the plugin doesn't force you to invent a fake "use" for them.

And the ancient relic — an item with no fragment at all¶

DA_AncientRelic is the same "Quest Letter" from the table in 01 — Core Concepts, just with a different name. Its Fragments array has zero entries. In practice that means:

doesn't stack — GetMaxStackSize() without a Stackable fragment always returns 1;
doesn't equip — no Equip button will appear, as for the ore or the potion;
does nothing on Use — there won't be a Use button either.

In the debug panel this is shown as plain text: the Fragments row for this item shows none, not an empty space. This isn't a broken item — it's the simplest possible item, and the system makes no exception for it: a quest item, a key, a story flag — all of these are an ISItemDefinition with no fragment, and nothing more is needed.

What we just saw¶

None of the seven examples added a single line to the inventory or equipment code. All the difference between the sword, shield, helmet, torch, potion, ore and relic is just a different set of fragments (and different values on them — the helmet and sword have the same fragments but different behaviour via one number, DurabilityPerUse) on the same ISItemDefinition class, from three fragments at once down to zero. That's the plugin's central idea: 01 — Core Concepts covers it in detail, with the same example table.

Where to next¶

You want	Read
Create your own item	03 — Authoring Items
Understand each fragment and its hooks	04 — Fragments
Build a pickup and equipment UI	08 — Building the UI
Place items and chests in a level	07 — Loot and world items
Everything about `DemoInvOverlay` and console commands	13 — Debugging