> ## Documentation Index
> Fetch the complete documentation index at: https://docs.appcharge.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Launch Checkout

### Setup the Product

In this step, create the product and configure its name, price, and additional information:

<CodeGroup>
  ```kotlin kotlin theme={"system"}
  val model = SessionRequestModel(  
      "John Doe",
      "[email protected]",
      129,
      "usd",
      "BestDealPackage",
      "Best_deal_package",
      "",
      "Coin Pack Bundle"  
  )  
  ```
</CodeGroup>

### Session Request Model Arguments

| Argument           | Is Mandatory | Description                                                                                            |
| ------------------ | ------------ | ------------------------------------------------------------------------------------------------------ |
| `customerId`       | **yes**      | The name or identifier of the customer.                                                                |
| `email`            | **no**       | The customer's email address. Although not mandatory, providing it helps expedite the payment process. |
| `price`            | **yes**      | The price in `cents`, which will be converted by `Appcharge`.                                          |
| `currency`         | **yes**      | The currency used for the transaction, e.g., `usd`, `eur`.                                             |
| `offerName`        | **yes**      | The name of the offer.                                                                                 |
| `offerSku`         | **yes**      | The SKU number or text for the offer.                                                                  |
| `offerAssetUrl`    | **no**       | A URL to display an image for the offer.                                                               |
| `offerDescription` | **yes**      | A description for the offer                                                                            |

### Session Metadata (Optional)

The session metadata allows you to add extra data for BI (Business Intelligence) and tracking purposes.

<CodeGroup>
  ```kotlin Kotlin theme={"system"}
  // Option 01: Use to get a parsable object string
  model.addSessionMetadata(key: String, value: String)
  // Example usage
  model.addSessionMetadata("sessionDetails", "details...")
  // Example Output
  /*
  {
  	...,
  	"sessionMetadata": "{\"sessionDetails\":\"details...\"}"
  }
  */

  // Option 02: Use to get any string
  model.sessionMetadata = "{...}"
  // Example usage
  model.sessionMetadata = "{ \"sessionDetails\": \"details...\" }"
  // Example output
  /*
  	{
    	...,
  		sessionMetadata: { "sessionDetails": "details..." }
    }

  */
  ```
</CodeGroup>

### Adding Items to the Offer

At least one item must be added to the offer.

```
val model = SessionRequestModel(...) // Your session model

model.addItem(  
    "Coins",
    "<https://media-dev.appcharge.com/media/product-3.png">,
    "Coins_xoxoxo",
    300,
    "300 Coins Booster"
)
```

### Offer Item Arguments

| Argument          | Is Mandatory | Description                                                                                                                                 |
| ----------------- | ------------ | ------------------------------------------------------------------------------------------------------------------------------------------- |
| `name`            | `mandatory`  | The name for the item                                                                                                                       |
| `assetUrl`        | `mandatory`  | An image asset for displaying the item                                                                                                      |
| `sku`             | `mandatory`  | The item SKU                                                                                                                                |
| `quantity`        | `mandatory`  | Amount of quantity for purchase. For example, if the `name` is "Coins" and the `quantity` is 300 then it it will be displayed as 300 Coins. |
| `quantityDisplay` | `mandatory`  | The `Quantity Display` allows you to replace the item quantity with a given text. Leave it as empty string to keep the quantity amount.     |

### Open Checkout

In this final step, open the checkout by passing the product model to it:

<CodeGroup>
  ```kotlin kotlin theme={"system"}
  bridge.openCheckout(model);
  ```
</CodeGroup>

At runtime, a new window will open, guiding the user through the purchase process. Based on user interaction, the following interface methods will be triggered:

| Method              | Description                                                                                       |
| ------------------- | ------------------------------------------------------------------------------------------------- |
| `OnPurchaseSuccess` | Triggered when the user successfully completes the purchase.                                      |
| `OnPurchaseFailed`  | Triggered when the checkout window is closed or if an error occurs during the purchasing process. |