# Action

Action represents a request that the frontend can send to a backend service.

Actions can be used to execute custom functions on the API hub such as requesting data from third-party services or updating the session information. Actions are called through custom endpoints known as action extensions. To learn more about action extensions, read the [developing an action extension](/frontend-development/developing-an-action-extension.md) documentation.

## Get data using an action

Use the GET method to allow the frontend to fetch data from a backend system.

Endpoint: `https://PROJECT_NAME-COMPANY_NAME.frontastic.TLD/frontastic/action/NAMESPACE/ACTION_NAME`
Method: `GET`
Headers:

- `Accept` - `application/json` - Required
- `Frontastic-Locale` - [Locale](/frontend-api/types.md#locale) - Required
- `Commercetools-Frontend-Extension-Version` - [Extension version](/frontend-development/extensions.md#extension-version) - Required

Path parameters:

- `PROJECT_NAME` - String - Required
- `COMPANY_NAME` - String - Required
- `TLD` - String - Required 
  The top-level domain for the environment, which includes `.live`, `.io`, and `.rocks`. For more information, see [Hosts](/frontend-api/general.md#hosts).
- `NAMESPACE` - String - Required 
  The namespace where the action to call is located. [Namespaces are used to categorize actions](/frontend-development/developing-an-action-extension.md#1-implement-the-action).
- `ACTION_NAME` - String - Required 
  The name of the action to call.

Response: we recommend to use standard HTTP response codes and `application/json` encoded content. The response will be structured [as defined by the `body` property of the action](/frontend-development/developing-an-action-extension.md#1-implement-the-action). The [response example](/frontend-api/action.md#response-example) contains information about a cart.

## Write data using an action

Use the POST or PUT method to write data to a backend system.

Endpoint: `https://PROJECT_NAME-COMPANY_NAME.frontastic.TLD/frontastic/action/NAMESPACE/ACTION_NAME`
Method: `POST` or `PUT`
Headers:

- `Accept` - `application/json` - Required
- `Frontastic-Locale` - [Locale](/frontend-api/types.md#locale) - Required
- `Commercetools-Frontend-Extension-Version` - [Extension version](/frontend-development/extensions.md#extension-version) - Required

Path parameters:

- `PROJECT_NAME` - String - Required
- `COMPANY_NAME` - String - Required
- `TLD` - String - Required 
  The top-level domain for the environment, which includes `.live`, `.io`, and `.rocks`. For more information, see [Hosts](/frontend-api/general.md#hosts).
- `NAMESPACE` - String - Required 
  The namespace where the action to call is located. [Namespaces are used to categorize actions](/frontend-development/developing-an-action-extension.md#1-implement-the-action).
- `ACTION_NAME` - String - Required 
  The name of the action to call.

Request body: any JSON serializable payload is accepted. The [request example](/frontend-api/action.md#request-example) adds a product to a cart.

Response: we recommend to use standard HTTP response codes and `application/json` encoded content. [The response will be structured as defined by the `body` property of the action](/frontend-development/developing-an-action-extension.md#1-implement-the-action). The [response example](/frontend-api/action.md#response-example) contains the updated cart information, which includes the added product.

## Examples

### Request example

```json
{
    "variant": {
        "sku": "M0E200KJ1200DSDJ",
        "count": 1
    }
}
```

### Response example

```json
{
    "cartId": "534a5f86-ea14-4b54-b2da-62a0672707e1",
    "cartVersion": "15",
    "lineItems": [
        {
            "lineItemId": "d41690bc-ea20-4254-b10b-8dxeac87c1b0",
            "productId": "6bgggaf4-c2b8-4ba7-945e-95e2a113a41f",
            "name": "Casual jacket",
            "type": "variant",
            "count": 1,
            "price": {
                "fractionDigits": 2,
                "centAmount": 39900,
                "currencyCode": "EUR"
            },
            "discountTexts": [],
            "discounts": [],
            "totalPrice": {
                "fractionDigits": 2,
                "centAmount": 39900,
                "currencyCode": "EUR"
            },
            "variant": {
                "id": "1",
                "sku": "M0E200KJ1200DSDJ",
                "images": [
                    "https://your-storage.com/images/casual_jacket.jpg"
                ],
                "groupId": "78d95",
                "attributes": {
                    "articleNumberManufacturer": "621840423 V0065",
                    "articleNumberMax": "78665",
                    "matrixId": "M0E200KJ1200DSDJ",
                    "baseId": "78665",
                    "designer": {
                        "key": "casual",
                        "label": "casual"
                    },
                    "madeInItaly": {
                        "key": "no",
                        "label": "no"
                    },
                    "commonSize": {
                        "key": "xxs",
                        "label": "XXS"
                    },
                    "size": "XXS",
                    "color": {
                        "key": "black",
                        "label": "Black"
                    },
                    "colorFreeDefinition": "black",
                    "style": {
                        "key": "sporty",
                        "label": "sporty"
                    },
                    "gender": {
                        "key": "men",
                        "label": "Men"
                    },
                    "season": "S15"
                },
                "price": {
                    "fractionDigits": 2,
                    "centAmount": 39900,
                    "currencyCode": "EUR"
                },
                "isOnStock": true
            },
            "isGift": false,
            "_url": "/slug/p/M0E200KJ1200DSDJ"
        }
    ],
    "sum": {
        "fractionDigits": 2,
        "centAmount": 39900,
        "currencyCode": "EUR"
    },
    "shippingAddress": {},
    "billingAddress": {},
    "payments": [],
    "discountCodes": []
}
```

## Related pages

- [Area overview page with navigation](/frontend-api.md)