Adding products to cart

How to add new items to your shopping cart

Problem

You want to implement the "add to cart" function on a product page. You have the order ID and either the new item ID or SKU code.

Solution

Adding a product (SKU) to a shopping cart means creating a new line item for an order. To do that, send a POST request to the /api/line_items endpoint, specifying the order and the SKU relationships.

Examples

Add an SKU to a shopping cart by ID

The following request adds the SKU identified by the "xYZkjABcde" ID to the order identified by the "yzkWXfgHQS" ID:

curl -g -X POST \
  'http://yourdomain.commercelayer.io/api/line_items' \
  -H 'Accept: application/vnd.api+json' \
  -H 'Authorization: Bearer your-access-token' \
  -H 'Content-Type: application/vnd.api+json' \
  -d '{
    "data": {
      "type": "line_items",
      "attributes": {
        "quantity": 1,
        "name": "Grey T-Shirt XL",
        "image_url": "https://img.yourdomain.com/skus/TSHIRTB5B5B5XL.png",
        "_update_quantity": true
      },
      "relationships": {
        "order": {
          "data": {
            "type": "orders",
            "id": "yzkWXfgHQS"
          }
        },
        "item": {
          "data": {
            "type": "skus",
            "id": "xYZkjABcde"
          }
        }
      }
    }
  }'

On success, the API responds with a 201 Created status code, returning the created (or updated) line item object:

{
  "data": {
    "id": "aBmNkPQRst",
    "type": "line_items",
    "links": {
      "self": "https://yourdomain.commercelayer.io/api/line_items/aBmNkPQRst"
    },
    "attributes": {
      "sku_code": "TSHIRTB5B5B5XL",
      "quantity": 2,
      "currency_code": "EUR",
      "unit_amount_cents": 12900,
      "unit_amount_float": 129.0,
      "formatted_unit_amount": "129,00€",
      "options_amount_cents": 0,
      "options_amount_float": 0.0,
      "formatted_options_amount": "0,00€",
      "total_amount_cents": 25800,
      "total_amount_float": 258.0,
      "formatted_total_amount": "258,00€",
      "name": "Grey T-Shirt XL",
      "image_url": "https://img.yourdomain.com/skus/TSHIRTB5B5B5XL.png",
      "tax_rate": null,
      "tax_breakdown": {},
      "item_type": "skus",
      "created_at": "2018-01-01T12:00:00.000Z",
      "updated_at": "2018-01-01T12:00:00.000Z",
      "reference": null,
      "metadata": {}
    },
    "relationships": {
      "order": {
        "links": {...}
      },
      "item": {
        "links": {...}
      },
      "line_item_options": {
        "links": {...}
      }
    },
    "meta": {
      "mode": "test"
    }
  }
}

If the quantity of the added item results higher than the available one in stock, the API responds with a 422 Unprocessable Entity error:

{
  "errors": [
    {
      "title": "is out of stock",
      "detail": "quantity - is out of stock",
      "code": "VALIDATION_ERROR",
      "source": {
        "pointer": "/data/attributes/quantity"
      },
      "status": "422",
      "meta": {
        "error": "out_of_stock"
      }
    }
  ]
}

Add an SKU to a shopping cart by code

The following request adds the SKU identified by the "TSHIRTB5B5B5XL" code to the order identified by the "yzkWXfgHQS" ID:

curl -g -X POST \
  'http://yourdomain.commercelayer.io/api/line_items' \
  -H 'Accept: application/vnd.api+json' \
  -H 'Authorization: Bearer your-access-token' \
  -H 'Content-Type: application/vnd.api+json' \
  -d '{
    "data": {
      "type": "line_items",
      "attributes": {
        "quantity": 1,
        "sku_code": "TSHIRTB5B5B5XL",
        "name": "Grey T-Shirt XL",
        "image_url": "https://img.yourdomain.com/skus/TSHIRTB5B5B5XL.png",
        "_update_quantity": true
      },
      "relationships": {
        "order": {
          "data": {
            "type": "orders",
            "id": "yzkWXfgHQS"
          }
        }
      }
    }
  }'

On success, the API responds with a 201 Created status code, returning the created line item object:

{
  "data": {
    "id": "aBmNkPQRst",
    "type": "line_items",
    "links": {
      "self": "https://yourdomain.commercelayer.io/api/line_items/aBmNkPQRst"
    },
    "attributes": {
      "sku_code": "TSHIRTB5B5B5XL",
      "quantity": 2,
      "currency_code": "EUR",
      "unit_amount_cents": 12900,
      "unit_amount_float": 129.0,
      "formatted_unit_amount": "129,00€",
      "options_amount_cents": 0,
      "options_amount_float": 0.0,
      "formatted_options_amount": "0,00€",
      "total_amount_cents": 25800,
      "total_amount_float": 258.0,
      "formatted_total_amount": "258,00€",
      "name": "Grey T-Shirt XL",
      "image_url": "https://img.yourdomain.com/skus/TSHIRTB5B5B5XL.png",
      "tax_rate": null,
      "tax_breakdown": {},
      "item_type": "skus",
      "created_at": "2018-01-01T12:00:00.000Z",
      "updated_at": "2018-01-01T12:00:00.000Z",
      "reference": null,
      "metadata": {}
    },
    "relationships": {
      "order": {
        "links": {...}
      },
      "item": {
        "links": {...}
      },
      "line_item_options": {
        "links": {...}
      }
    },
    "meta": {
      "mode": "test"
    }
  }
}

If the quantity of the added item results higher than the available one in stock, the API responds with a 422 Unprocessable Entity error:

{
  "errors": [
    {
      "title": "is out of stock",
      "detail": "quantity - is out of stock",
      "code": "VALIDATION_ERROR",
      "source": {
        "pointer": "/data/attributes/quantity"
      },
      "status": "422",
      "meta": {
        "error": "out_of_stock"
      }
    }
  ]
}

Additional notes

The `_update_quantity` param

Specifying "_update_quantity": true (or "_update_quantity": 1) in the request body lets you update the existing line item quantity (if any) instead of creating a new line item for the same SKU. That means:

if the item is already present in the shopping cart, its line item quantity attribute is updated
if the item is not present in the shopping cart a new line item is created and its quantity attribute is set to the quantity value

If you send the POST request without the "_update_quantity": true (or "_update_quantity": 1) param a new line item is always created, even if the line item SKU is already present in the shopping cart.

The `name` and `image_url` fields

When creating a new line item, the only required attribute is quantity. Anyway, we recommend always populating the name and image_url fields (like in the examples above) in order to show the desired name and image in the cart summary and order management. When empty, Commerce Layer will try to populate name and image_url from the associated SKU fields.