> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/martin-ratti/PCFIX-Baru/llms.txt
> Use this file to discover all available pages before exploring further.

# Update Cart Item

> Update the quantity of an item in the shopping cart

## Overview

Updates the quantity of an existing product in the user's shopping cart. This endpoint uses the cart synchronization mechanism to modify item quantities.

## Authentication

This endpoint requires authentication. Ensure the user is authorized to modify the cart.

## Request Body

<ParamField body="userId" type="number" required>
  The unique identifier of the user whose cart you want to modify
</ParamField>

<ParamField body="items" type="array" required>
  Array of all cart items with updated quantities

  <ParamField body="id" type="string" required>
    The product ID (as a string)
  </ParamField>

  <ParamField body="quantity" type="number" required>
    The new quantity for the product (must be greater than 0)
  </ParamField>
</ParamField>

## Cart Item Structure

Each cart item contains:

* **id**: Product identifier (string format)
* **quantity**: Number of units (positive integer)

## Response

<ResponseField name="success" type="boolean" required>
  Indicates whether the request was successful
</ResponseField>

<ResponseField name="data" type="object">
  The complete updated cart object

  <ResponseField name="id" type="number">
    Unique identifier for the cart
  </ResponseField>

  <ResponseField name="userId" type="number">
    The ID of the user who owns this cart
  </ResponseField>

  <ResponseField name="items" type="array">
    Array of all cart items with updated quantities

    <ResponseField name="id" type="number">
      Unique identifier for the cart item
    </ResponseField>

    <ResponseField name="productoId" type="number">
      The product ID for this cart item
    </ResponseField>

    <ResponseField name="quantity" type="number">
      Updated quantity of the product
    </ResponseField>

    <ResponseField name="producto" type="object">
      Complete product details
    </ResponseField>
  </ResponseField>
</ResponseField>

<ResponseField name="error" type="string">
  Error message if the request fails
</ResponseField>

## Example Request

### Update Single Item Quantity

```bash theme={null}
curl -X POST "https://api.pcfix.com/api/cart/sync" \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "userId": 123,
    "items": [
      {
        "id": "789",
        "quantity": 5
      },
      {
        "id": "456",
        "quantity": 1
      }
    ]
  }'
```

### Update Multiple Items

```bash theme={null}
curl -X POST "https://api.pcfix.com/api/cart/sync" \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "userId": 123,
    "items": [
      {
        "id": "789",
        "quantity": 3
      },
      {
        "id": "456",
        "quantity": 2
      },
      {
        "id": "321",
        "quantity": 4
      }
    ]
  }'
```

## Example Response

### Success Response

```json theme={null}
{
  "success": true,
  "data": {
    "id": 1,
    "userId": 123,
    "abandonedEmailSent": false,
    "items": [
      {
        "id": 45,
        "cartId": 1,
        "productoId": 789,
        "quantity": 5,
        "producto": {
          "id": 789,
          "name": "Gaming Mouse",
          "price": 49.99,
          "description": "High-performance gaming mouse"
        }
      },
      {
        "id": 46,
        "cartId": 1,
        "productoId": 456,
        "quantity": 1,
        "producto": {
          "id": 456,
          "name": "Mechanical Keyboard",
          "price": 129.99,
          "description": "RGB mechanical keyboard"
        }
      }
    ]
  }
}
```

### Error Response

```json theme={null}
{
  "success": false,
  "error": "User ID required"
}
```

## Error Codes

| Status Code | Description                        |
| ----------- | ---------------------------------- |
| 200         | Item quantity updated successfully |
| 400         | Invalid user ID or request body    |
| 401         | Unauthorized access                |
| 500         | Server error - Failed to sync cart |

## Important Notes

<Warning>
  The sync endpoint replaces ALL cart items. To update an item's quantity, you must include ALL cart items in the request with their current or updated quantities.
</Warning>

<Info>
  To effectively increase or decrease quantity:

  1. First, fetch the current cart using GET `/api/cart/:userId`
  2. Modify the quantity of the desired item(s)
  3. Send all items back with the updated quantities
</Info>

## Quantity Updates

* Quantities must be positive integers (greater than 0)
* To remove an item, omit it from the items array (see Remove Item documentation)
* Setting quantity to 0 will not remove the item; you must exclude it from the array
* The `abandonedEmailSent` flag is reset to `false` when quantities are updated
* Invalid product IDs are automatically filtered out during sync