# Custom callbacks

Handle custom callback requests from paywalls to run app-side logic and return results.

> **Info**

Available from Android SDK 2.7.0.



Overview [#overview]

Custom callbacks let a paywall request arbitrary actions from your app and receive results that determine which branch (`onSuccess` / `onFailure`) executes inside the paywall. Common use cases include validating user input, fetching data, or running business logic that lives outside the paywall.

How it works [#how-it-works]

1. In the paywall editor, attach a **Custom callback** action to an element (button, form submit, etc.) and give it a name (e.g. `validate_email`).
2. When the user triggers that element the SDK calls your `onCustomCallback` handler with a `CustomCallback` object.
3. Your handler runs whatever logic is needed and returns a `CustomCallbackResult` — either `.success()` or `.failure()` — with optional data.
4. The paywall receives the result and executes the matching `onSuccess` or `onFailure` branch.

Setting up the handler [#setting-up-the-handler]

Register the handler on a `PaywallPresentationHandler` before calling `register`:

```kotlin
val handler = PaywallPresentationHandler()

handler.onCustomCallback { callback ->
    when (callback.name) {
        "validate_email" -> {
            val email = callback.variables?.get("email") as? String
            if (isValidEmail(email)) {
                CustomCallbackResult.success(mapOf("validated" to true))
            } else {
                CustomCallbackResult.failure(mapOf("error" to "Invalid email"))
            }
        }
        else -> CustomCallbackResult.failure()
    }
}

Superwall.instance.register(placement = "campaign_trigger", handler = handler) {
    // Feature launched
}
```

CustomCallback [#customcallback]

The `CustomCallback` data class is passed to your handler:

<TypeTable
  type="{
  name: {
    type: &#x22;String&#x22;,
    description: &#x22;The name of the callback set in the paywall editor.&#x22;,
    required: true,
  },
  variables: {
    type: &#x22;Map<String, Any>?&#x22;,
    description: &#x22;Optional key-value pairs sent from the paywall. Values are type-preserved (String, Number, Boolean).&#x22;,
  },
}"
/>

CustomCallbackResult [#customcallbackresult]

Return one of the following from your handler to signal the outcome:

```kotlin
// Success — the paywall's onSuccess branch runs
CustomCallbackResult.success(data = mapOf("key" to "value"))

// Failure — the paywall's onFailure branch runs
CustomCallbackResult.failure(data = mapOf("error" to "Something went wrong"))
```

Both `success()` and `failure()` accept an optional `data` map whose values are sent back to the paywall and accessible as `callbacks.<name>.data.<key>`.

Callback behavior [#callback-behavior]

When configuring the custom callback action in the paywall editor you can choose between two behaviors:

* **Blocking** — the paywall waits for your handler to return before continuing the tap-action chain. Use this when the next step depends on the result (e.g. form validation).
* **Non-blocking** — the paywall continues immediately. The `onSuccess` / `onFailure` handlers still fire when the result arrives, but subsequent actions in the chain do not wait.

Accessing returned data in the paywall [#accessing-returned-data-in-the-paywall]

Inside the paywall you can reference the returned data using the pattern `callbacks.<callback_name>.data.<key>`. For example, if the callback named `validate_email` returns `mapOf("validated" to true)`, the paywall can access `callbacks.validate_email.data.validated`.