> For the complete documentation index, see [llms.txt](https://docs.otherside.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.otherside.xyz/odk-docs/odk-plugin/nfts-tokens/token-handlers.md).

# Token Handlers

**Token Handlers** are objects that react to token changes inside the ODK wallet. They live on the wallet component of the Morpheus player character and define what happens when a token is **added, removed, or updated** — such as triggering a quest, showing some UI, or playing a VFX.

The system is modular, data-driven, and highly extendable via Blueprints.

***

### 🔩 Where Token Handlers Live

Token Handlers are configured on the player's wallet component:\
📍 `BPMC_ODK_WalletComponent`\
Found on: `BPM_ODK_PlayerCharacterBase` or your project’s subclass.

Inside the component, you’ll find a map:

```cpp
Map<string, BP_ODKFilterSet>
```

Each entry defines a **filter set** with an arbitrary name and the handler that should respond if a token passes that filter.

***

#### Example Use Case:

* Filters for tokens with `type == "quest"`
* Handler: `BP_ODKTokenHandler_Quest` - Shows Quest UI information

***

### 🧪 How Filtering Works

Each filter in the filter set must implement the function:

```cpp
IsRelevantToken(TokenData) → bool
```

This function inspects the token metadata and determines if it matches your logic.

If ALL **of the filters return `true`**, the **assigned Token Handler is activated**.

***

### 🧰 Built-in Example Filters

You can find reusable example filters in the plugin:

#### 🧾 `BP_ODKTokenFilter_TokenType`

* Checks the `type` field in token metadata
* Accepts a **whitelist of strings**
* Example: match `type == "quest"` or `type == "achievement"`

***

#### 🧮 `BP_ODKTokenConditionGroup`

* Used to **group filters together** in more advanced logic
* Contains:

  * `Filters[]`: array of AND'd filters - All filters must pass
  * `OR Filter`: a single filter that acts as an OR condition.

  The OR filter is a single filter because it allows nesting of `ConditionGroups`, allowing complex condition trees

**Example:**

```plaintext
( TokenType == "quest" ) 
  OR 
( ConditionGroup
    (TokenType == "achievement")
            AND
    (ChainID == "33139")
)
```

***

### 🛠 Creating Your Own Filters

To create custom filters:

1. Inherit from `BP_ODKTokenFilterBase`
2. Implement `IsRelevantToken`
3. Add any parameters you want to expose (e.g. tags, substrings, reward keys)

Custom filters give you full control over how tokens are routed, enabling:

* Campaign-specific logic
* Filtering by metadata fields like XP, group, or even token balance

***

### 🎯 Creating Your Own Token Handlers

Handlers inherit from `BP_ODKTokenHandlerBase` and define what happens when a relevant token event occurs.

Each handler receives the `TokenUpdate` function containing the filtered token and the update type (Add, Update, Remove etc)

Token handlers allow for custom logic for a filtered token, for example:

For all tokens with "type" "quest"

* Fire off UI or sound
* Trigger Task Flows

For all tokens with "type" "badge"

* Start cinematics
* Queue unlocks
* Animate overlays

***

### ✅ Best Practices

* Use meaningful filter set names (`"quest notifications"`, `"achievement unlocked"`)
* Reuse modular filters (e.g. shared `TokenType` filters)
* Keep filters lightweight — heavy logic should live in handlers
* Avoid putting too much logic inside `IsRelevantToken` — keep it as a pass/fail gate

***

### 🧵 Summary Flow

```plaintext
1. Token is added/removed/updated
2. Each Filter Set checks if the token matches its filter(s)
3. If matched → corresponding Token Handler is triggered
```


---

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